IT terms explained in plain English
Practical definitions of core concepts — from classic networking to modern AI. Short enough to read fast, long enough to actually learn something.
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Networking803 termsHTTP/2 · Split horizon · TCP BBR · Native VLAN
Web649 termsVitest · Fastly · Flexbox · Haml
Programming2 082 termsCoulomb friction · Octree · Subroutine · Scope
AI & ML495 termsWaveNet · RadixAttention · N-gram · Chain-of-thought
Security2 060 termsBeaconing · Ben Adida · Cube attack · Niels Provos
Infra & Ops1 296 termsDocker Swarm · xdaliclock · NetApp · XenSource
Hardware2 125 termsMellotron · Low-pass filter · Floptical · Maxtor
Database473 termsMulti-leader · Business Objects · BRIN index · Saga
Chat & Social Media1 161 termsFuture Composer · monday.com · n8n · Kibo
0–9
- 10 GbE10 Gigabit Ethernet — standard since 802.3ae (2002). Standard in datacenter since the 2010s. Prosumer adoption 2024+: 10GbE…
- 10DLCThe US carriers' way of letting A2P texts ride on ordinary ten-digit local numbers — provided the business registers a brand…
- 1541 UltimateA cartridge that impersonates a Commodore 1541 disk drive, right down to the processor inside it, and loads disk images from…
- 16-bitThe middle chapter of computing history: enough for real programs, but only 65,536 addresses to put them in.
- 16colo.rsA web archive that preserves decades of ANSI and ASCII art in monthly artpacks.
- 1K introA demo that fits in 1,024 bytes — twice as roomy as a 256-byte intro, yet still an exercise in extreme thrift.
- 1PasswordCanadian password manager, and the company behind it, that grew from a Mac utility into an enterprise platform.
- 2.5 GbE2.5 Gigabit Ethernet — 802.3bz standard (2016). Works over Cat5e + Cat6 (existing cables), not Cat6a/7 required like 10GbE…
- 256-byte introAn intro whose entire program fits in 256 bytes, one of the demoscene's harshest size classes.
- 2bwmA minimalist floating window manager for X11 with two borders around each window and nothing else, forked from mcwm.
- 2D lightingDynamic lights and shadows in a flat sprite world, faked with normal maps and 2D shadow casters because there is no real…
- 2FA / MFATwo- or multi-factor authentication — you have to prove who you are with two independent things.
- 3-D SecureThe protocol that lets the card issuer check who is actually at the keyboard when a card is used online.
- 3-subset meet-in-the-middleA meet-in-the-middle variant that splits the key bits into three groups and works against ciphers whose key schedule merely…
- 3-WayA compact block cipher by Joan Daemen from 1994, built for fast hardware rather than elegant software.
- 32-bitFour gigabytes sounded infinite in 1985 and became the most keenly felt ceiling of the 2000s.
- 37signalsThe small Chicago shop that gave the world Basecamp, Rails and an entire genre of opinions on how to run a company.
- 3ComThe company Ethernet's inventor founded to sell his own invention, and for two decades a fixture in nearly every PC's…
- 3D printerA machine that builds physical objects layer by layer instead of cutting them out of a solid block.
- 3D RealmsApogee's 3D label, which made Duke Nukem 3D and then spent fourteen years not finishing the sequel.
- 3D XPointA memory technology (Intel + Micron, 2015) meant to fill the gap between fast volatile DRAM and slow persistent NAND flash…
- 3DESDES three times over, because twice does not help — a patch that kept the banking system running for twenty-five years.
- 3dfxThe company whose Voodoo cards made 3D acceleration something every PC gamer needed, and which was gone four years later.
- 3DOThe console the company never built itself — it licensed out the design and let others lose money on it.
- 3PARThe enterprise-storage company whose thin provisioning was good enough to touch off a bidding war between HP and Dell.
- 464XLATIPv4-on-IPv6-only-network transition mechanism. RFC 6877 (2013). Combines client-side stateless translation (CLAT) +…
- 4chanAn anonymous imageboard started in 2003 by fifteen-year-old Christopher Poole ("moot"), built as an English-language copy of…
- 4DwmSGI's window manager on IRIX, an extended descendant of Motif's mwm that became the visible face of Indigo Magic.
- 4K introA demo of at most 4096 bytes — all the graphics and music are computed on the fly.
- 4klangA modular software synth from the group Alcatraz that lets musicians write 4k music in an ordinary sequencer.
- 4matBritish musician Matthew Simmonds, one of the people who turned chip sound into a style of its own on the Amiga.
- 4SightSilicon Graphics' window system for IRIX in the late 1980s, built on Sun's NeWS with 3D graphics running right inside the…
- 528 MB barrierThe notorious ceiling of 504 MiB that arose when the BIOS INT 13h and IDE interfaces had incompatible maximums for…
- 5G mmWave5G on 24-100 GHz spectrum. Massive bandwidth (400 MHz channels) → multi-gigabit speeds. Trade-off: ~200m range, blocked by…
- 5G NR (New Radio)5G's air interface — 3GPP Release 15+ (2018). Successor to LTE (4G). Two frequency ranges: FR1 (sub-6GHz, mainstream), FR2…
- 5G NSA (Non-Standalone)5G deployment mode: 5G radio + LTE core. Phone latches onto a 4G cell for control-plane, on 5G for user-plane throughput…
- 5G SA (Standalone)5G with a 100% 5G core network. Distinct from 5G NSA (Non-Standalone) which uses an LTE core with 5G radio. SA enables…
- 64-bitCPU architecture where registers, addresses, and pointers are 64 bits wide. Standard since ~2005–2010. Addresses up to 16 EB…
- 64k introA demo compo class where the whole production — code, music and graphics — must fit in 65536 bytes, forcing everything to be…
- 64klang4klang's big brother: a software synth from the group Alcatraz, built for music in 64k intros where the soundtrack gets a…
- 64tassA cross-assembler for the 6502 family that runs on a PC but speaks the syntax of the C64's own Turbo Assembler.
- 669 formatAn early module format for the PC, named after its file extension — Composer 669 made tracked music on the PC before S3M and…
- 6to4IPv6-over-IPv4 tunneling mechanism. RFC 3056 (2002). A public-IPv4 address mapped automatically to an IPv6 prefix…
- MOS 6502The processor that cost $25 when the competition cost two hundred, and therefore sits inside half of the 1980s.
- 7-track tapeThe first commercial magnetic-tape format — six data bits plus parity across half-inch tape, born with the IBM 701 in 1952.
- 8-bitEight bits is enough for 256 values, one character, or an entire generation of home computers.
- 80 PLUSA certification of power supply efficiency. The base requirement is at least 80 percent efficiency at 20, 50 and 100 percent…
- 802.1XIEEE standard for port-based network access control. Client (supplicant) authenticates against a RADIUS server via a switch…
- 8½Plan 9's first window system, written by Rob Pike and named after the Fellini film.
- 8SVXThe Amiga's native sampled-audio format — 8-bit sound packed as an IFF chunk, the raw material that tracker instruments were…
- 8x8The video-codec chip maker that traded silicon for cloud phone service and named itself after a pixel block.
- 9 FingersSpaceballs' 1993 Amiga demo that played back digitised film on a machine that had no business doing so.
- 9-track tapeThe open half-inch reel with nine parallel tracks that was the computer tape from 1964 and became the very image of…
- 96-column cardIBM's attempt to modernise the punched card — smaller, denser, and about a decade late.
- 9wmAn X window manager that imitated Plan 9's 8½ as faithfully as X allowed: no buttons, no icons, one menu and thin borders.
A
- A Manual of Operation for the ASCCFive hundred pages from 1946 on how to make a machine do what you intended — the world's first programming manual, written…
- A NewsThe very first Usenet software, built at Duke for a network where a handful of posts a day counted as busy.
- A Symbolic Analysis of Relay and Switching CircuitsThe thesis that showed a network of relays is Boolean algebra rendered in brass — turning circuit design from guesswork into…
- A-weightingA filter curve that rolls off bass and extreme treble before a sound level is measured, so the reading tracks how the ear…
- A* (A-star)Pathfinding algorithm that finds the shortest path in a graph — Dijkstra plus a heuristic that steers search toward the goal.
- A/B testing (Split testing)Show two variants (A=control, B=treatment) to randomly selected users; measure which performs better on a metric. Standard…
- A10 NetworksA San Jose load-balancer vendor that does very nicely out of the world running short of IPv4 addresses.
- A100Nvidia's data center GPU from 2020, built on the Ampere architecture. The workhorse that trained the first generation of…
- a11y (Accessibility)Shorthand for "accessibility" — making sites usable for everyone, including people with disabilities.
- A2DP (Advanced Audio Distribution Profile)The Bluetooth profile that streams stereo audio one way, from phone to headphones, and the one that decides which codec gets…
- A2P (application-to-person)The traffic class where a system, not a person, sends the SMS — one-time codes, delivery alerts and marketing that carriers…
- A5/1The stream cipher that protected GSM calls in Europe — secret from 1987 until it leaked, and broken in practice in 2009.
- AA-libA C library that renders arbitrary graphics as ASCII characters, so video and games can run in a plain text terminal.
- AABBA bounding box whose edges run parallel to the coordinate axes, so it is described by nothing more than a minimum and a…
- AAC (Advanced Audio Coding)MP3's successor — better audio at the same bitrate, and the format behind iTunes, YouTube and digital radio.
- AAF (Advanced Authoring Format)The file format that carries an edited project — clips, positions, fades — between applications from different vendors.
- Aaron RothThe computer scientist who wrote the differential privacy textbook with Cynthia Dwork and then turned the same maths against…
- Aaron SwartzCo-wrote the RSS specification at fourteen and went on to build a sizeable part of the open web's infrastructure.
- AAudioAndroid's low-latency C audio API, introduced in Android 8.0 as an attempt to make the phone usable as a musical instrument.
- AAXAvid Audio eXtension — the only plugin format Pro Tools will load, and the reason every plugin vendor builds the same code…
- ABAC (Attribute-Based Access Control)Authorization model where decisions are based on attributes of the user, resource, and context — more flexible than RBAC but…
- AbacusA calculating tool that stores the digits but leaves the algorithm to the human — which is why it can still beat a trained…
- Abbreviated menu button (OPEN LOOK)OPEN LOOK's compact menu button: a small square with a downward triangle and no label, for places where a full labelled…
- ABC 80Sweden's own home computer: designed by DIAB, built by Luxor in Motala and installed in nearly every Swedish classroom of…
- ABC notationMusic notation in plain text, where a tune fits in an email and can be read without any software.
- AberMUDThe MUD from Aberystwyth that spread to university machines worldwide and turned the genre into something you could run…
- ABI (Application Binary Interface)Low-level contract between compiled binaries — how functions are called, parameters passed, return values handled.
- ABL modeArbitrary Block Length: a mode that stretches an ordinary 128-bit cipher into a block cipher the size of a whole disk sector.
- Ableton LinkTempo sync over the local network with no master: every device agrees on the beat among themselves.
- Ableton LiveThe Berlin DAW built for playing live rather than recording, which is why it looks like a spreadsheet of loops.
- AblyLondon-based realtime platform that extends pub/sub with explicit guarantees about message ordering and recovery after a…
- AbortControllerA web API for aborting ongoing asynchronous operations — primarily fetch calls, but also event listeners and more. You…
- Abraham SinkovAmerican cryptanalyst who carried a PURPLE replica to Bletchley Park in 1941.
- Abreast-DMTwo Davies–Meyer steps side by side under the same key, one of them fed the bitwise complement of the chaining value so the…
- Absolute threshold of hearingThe faintest sound level a person can detect in complete silence — a figure that swings wildly with frequency.
- Abstract classA class that can't be instantiated directly — only inherited. Defines partial implementation with some methods subclasses…
- AbstractionHiding complexity behind a simpler interface.
- ABX testA double-blind listening test in which X is randomly either A or B and the listener has to say which — the only way to show…
- AC bias recordingA high-frequency tone mixed on top of the signal during magnetic recording that straightens the medium's crooked transfer…
- AC network analyzerBefore you could simulate a power grid in software, you built a shrunken electrical copy of it on a wall of dials and read…
- AC'97Intel's 1997 specification that moved PC audio off the expansion card and onto the motherboard, split between a digital…
- Accelerated-XXi Graphics' commercial X server for Linux and other PC Unixes, which through the 1990s sold drivers for graphics cards and…
- AccentureThe consulting giant that changed its name and cut ties with its accounting parent months before Enron took the parent down.
- Access point (AP)The device that turns wired Ethernet into Wi-Fi. In a home network it lives inside the router; in any larger installation…
- Access timeThe total time from a read request to the first byte delivered — the sum of seek time, rotational latency and the…
- Access tokenThe short-lived "key" the client sends with every API call to prove it's allowed to do something. Typically a JWT or an…
- Accessibility (A11y)Designing for users with disabilities — visual, motor, cognitive, hearing. Abbreviated A11y (11 letters between A and y).
- AccessXThe keyboard accessibility aids in X, sticky modifiers, slow keys and mouse control from the numeric keypad, which arrived…
- AccoladeThe publisher that reverse-engineered Sega's console and won the right to do so in court.
- AccordionUI pattern: a list of collapsible sections, click expands. Shows lots of info without filling the screen. Most common for…
- Accounting machineThe punched-card era's report generator: a programmable tabulator that read decks of cards, summed fields and printed…
- Accumulation bufferAn extra high-precision image buffer in which several renders of the same scene are summed and averaged into one picture.
- AccumulatorA special CPU register that all arithmetic/logic operations implicitly use as one operand and result. Classic architecture…
- Accumulator unit (ENIAC)Twenty cabinets that were memory and arithmetic in the same box — ENIAC's entire fast storage held twenty numbers, each…
- ACETuring's own 1945 computer design — faster and more idiosyncratic than von Neumann's, yet so ambitious that only a…
- AcerTaiwan's first big PC brand, which grew by buying the American budget labels it once competed with.
- ACH (Automated Clearing House)The US network for bulk bank transfers – payroll, bills and direct debits, settled in batches rather than one at a time.
- AchaeaA text MUD that was free to play but sold credits — the business model that later swallowed the games industry.
- AchronixAn independent FPGA maker that sells both finished chips and embeddable programmable logic as IP.
- ACIDFour guarantees a transaction should meet: Atomicity, Consistency, Isolation, Durability.
- ACiD ProductionsThe most influential ANSI art group, founded in 1990 and known for its monthly art packs.
- ACiDDrawA DOS ANSI editor from the ACiD art group, made by the scene's own artists for themselves.
- ACME (Automatic Certificate Management Environment)The protocol that automates issuing and renewing TLS certificates.
- Acorn ArchimedesBritish home computer from 1987 and the first built around an ARM processor — the same architecture now inside nearly every…
- Acorn ComputersThe Cambridge firm that built Britain's school computer and, almost as a side project, invented the processor architecture…
- Acoustic couplerThe modem you pressed a telephone handset into, because attaching your own equipment to the phone line was forbidden.
- Acoustic cryptanalysisA side-channel attack that recovers keys from the sound a computer makes while it computes.
- Acoustic echo cancellationWhat stops the other caller's voice from leaving your loudspeaker, entering your microphone and returning to them as an echo…
- ACPI (Advanced Configuration and Power Interface)The standard that lets the operating system control power management and hardware configuration instead of the BIOS. Created…
- Acquire-releaseThe memory ordering that lock-free code almost always actually wants: strong enough to synchronise two threads through one…
- AcquirerThe bank or payments company that accepts card payments on a merchant's behalf and makes sure the money lands in the…
- AcronisBest known for the True Image disk-imaging software, now repackaged as "cyber protection" with backup and anti-malware…
- Action ReplayDatel's freezer cartridge that could halt a program mid-stride, dump memory and back up almost anything.
- Actions (CDE)CDE's database of what a double-click does: named commands in .dt files that the file manager, the Front Panel and the shell…
- ActionScriptThe programming language for Adobe Flash — ECMAScript-based (same root as JavaScript). v1 1998, v3 2006, died when Flash…
- Activation functionThe function each neuron in a neural network runs its inputs through — what gives the network non-linearity.
- active (Usenet)A news server's list of which groups exist, which article numbers they hold and whether posting is allowed.
- Active DesktopMicrosoft's 1997 attempt to turn the desktop wallpaper into a web page with "channels" streaming news: the most visible…
- Active Directory (AD)Microsoft's directory service for Windows domains — users, groups, computers, policies, all in one place.
- Active ragdollA ragdoll whose joints are driven by motors toward an animated pose, so the character stays physically simulated yet can…
- Active SensingMIDI's heartbeat — a byte sent over and over so the receiver notices when the cable gets pulled.
- ActiveXMicrosoft's plugin technology for Internet Explorer (1996) — ran native COM components inside the browser. Killed by IE's…
- ActivisionThe first independent console game developer, founded by programmers fed up with Atari refusing to put their names on the…
- Activities (KDE Plasma)Plasma's attempt to go one step beyond virtual desktops: not just "where are the windows" but "what am I doing" — with its…
- ActivityPubW3C-standardised protocol (2018) for federated social networks — every server talks to others by posting JSON-LD activities…
- Actor modelConcurrency model where "actors" are autonomous units that communicate exclusively via asynchronous messages — no shared…
- AdaA language commissioned by the US Department of Defense around 1980 to replace the hundreds of languages then used in…
- Ada LovelaceNvidia's consumer GPU architecture, launched October 2022. RTX 4090, 4080, 4070, 4060. TSMC 4N. 2x ray-tracing perf vs…
- Ada Lovelace (person)The mathematician who in 1843 wrote what is generally counted as the world's first computer program — for a machine that was…
- AdafruitNew York company that sells electronics to hobbyists and publishes the design files for nearly everything it makes.
- AdamThe optimization algorithm practically all deep learning uses. The name stands for adaptive moment estimation. Published by…
- Adam BackBritish cryptographer and cypherpunk who invented Hashcash in 1997, the proof-of-work scheme that later became Bitcoin's…
- Adam LangleyGoogle's TLS engineer who has quietly rebuilt much of the web's transport encryption, from BoringSSL to post-quantum trials…
- Adam ShostackThe person who turned threat modeling into something developers actually do, rather than something consultants bill for.
- Adam YoungAmerican researcher who described public-key ransomware in 1996, about fifteen years before criminals caught on.
- AdamWAdam optimizer with "decoupled weight decay" — Loshchilov & Hutter (2017). The default for training every modern LLM.
- AdaptecIn the SCSI era the company's name was effectively a synonym for the card you slotted into a machine to attach hard drives…
- Adapter patternGang-of-Four structural pattern — wrap a class so its interface looks like another. "Pipe-to-pipe adapter".
- Adaptive hash indexInnoDB's automatic shortcut that builds a hash table over the index prefixes you look up most often, so a point lookup skips…
- Adaptive iconAndroid's answer to every manufacturer wanting its own icon shape — the app ships two layers, the system does the cropping.
- Adaptive musicGame music that changes with the state of play — ramping up in combat, thinning out while exploring, dropping a stinger on a…
- ADATAn eight-track digital tape machine from 1991 that died out — and an optical cable from the same box that lives on in almost…
- ADBAndroid Debug Bridge — the command line tool connecting your computer to an Android device over USB or the network.
- ADCS ESC1A misconfigured certificate template that lets any user request a certificate issued in the domain administrator's name…
- AddiatorA flat pocket adder of metal slides and a stylus — addition without a single gear, popular until electronics ran it over.
- Additive animationAdd the difference between two poses on top of a running animation instead of blending between whole poses.
- Additive blendingA blend mode that adds the source colour on top of what is already in the buffer — light piles onto light.
- Additive synthesisBuilding a sound by summing sine waves, one per partial — Fourier run in reverse.
- Address markA special bit pattern on an FM- or MFM-formatted disk that tells the controller where a sector ID or a data block begins.
- AddressSanitizer (ASan)Compiler-based memory error detector from Google (2012). Compile with -fsanitize=address and the program aborts at the first…
- Adele GoldstineShe wrote the ENIAC manual — nearly 550 pages that were the machine's only documentation, and therefore the first…
- ADF (Amiga Disk File)A sector-by-sector image of an Amiga floppy — the emulator world's de facto standard.
- ADFGVX cipherA German field cipher from 1918 that combined substitution with transposition, and was broken by a Frenchman within months…
- ADFGX cipherA German field cipher from World War I that combined a Polybius square with a columnar transposition.
- Adi ShamirThe S in RSA, and the man who made breaking other people's cryptosystems a sport — colleagues' included.
- AdiantumA length-preserving encryption mode built on ChaCha and Poly1305, meant for devices without AES hardware.
- Adjacency listThe simplest and most common way to store a tree in SQL: each row has a parent_id pointing to its parent. Easy to understand…
- Adjacent-track interferenceRepeated writes to one track slowly erase its neighbours as tracks are packed tight — ATI.
- ADL (Argument-Dependent Lookup)The C++ rule that on an unqualified function call the compiler also searches the namespaces belonging to the argument types…
- AdLibCanadian sound card from 1987 that brought FM synthesis to the PC — before the Sound Blaster ate its lunch.
- Administrative distance (AD)A measure of how "trustworthy" an information source is when a router has learned the same route from several routing…
- AdminSDHolderThe object whose access control list serves as the template for every privileged account in the domain. A background process…
- Admission controllerA "gate" in the Kubernetes API server that reviews every request to create/modify an object AFTER authentication but BEFORE…
- AdMobGoogle's advertising network for mobile apps — the revenue model that made the free app the default format.
- ADO.NETMicrosoft's data access layer for .NET — the low level beneath every ORM, where you still write SqlConnection by hand.
- AdobeOwns the file formats graphic production rests on — PostScript, PDF, and a long line of programs whose names became verbs.
- Adobe AuditionAdobe's audio editor, which started life as the shareware program Cool Edit and is now mostly used for speech, podcasts and…
- Adobe FireflyAdobe's family of generative AI models, launched in March 2023. The selling point isn't primarily quality but provenance…
- Adobe FontsAdobe's web-font service — previously called Typekit (Adobe bought 2011). Renamed Adobe Fonts October 2018. Included in…
- ADPAmerican payroll giant that started doing the maths by hand in 1949 and never stopped — now it does it for tens of millions…
- ADPCMAudio compression that stores the difference from a prediction rather than the sample itself, with a step size that adapts…
- Adrian LamoThe "homeless hacker" who walked into corporate networks from internet cafés, and who later turned in Chelsea Manning.
- Adrian PerrigSwiss researcher who thinks internet routing is too important to be left to BGP's good faith.
- Adrienne Porter FeltResearcher and engineer who turned usable security into something you could measure — and got Chrome to call plain HTTP…
- ADSRThe four-stage model of how a note starts, falls, holds and dies away — a synthesizer's way of admitting that real…
- Advanced Art StudioA windowed paint program for the Commodore 64 from the mid-1980s, built around the machine's fiddly multicolor mode.
- Advanced FormatThe move from 512-byte to 4K physical sectors on hard drives — less overhead and stronger error correction, but sensitive to…
- Advanced packagingTechniques to integrate multiple chiplets on the same substrate or stack them 3D. CoWoS (TSMC), Foveros (Intel), EMIB…
- AdvantestThe test machines that, together with Teradyne, decide whether the world's chips pass — splitting the market almost evenly…
- Adventure Game Studio (AGS)The free tool that kept the point-and-click adventure alive after the big publishers had given up on it.
- Advisory lockPostgreSQL feature: application-defined locks without ties to rows/tables. SELECT pg_advisory_lock(12345). DB keeps track…
- AdyenThe Amsterdam company that processes card payments for Uber, Spotify and eBay on a single in-house platform, online and at…
- AerospikeNoSQL database built to answer in under a millisecond at millions of operations per second, by keeping the index in RAM and…
- AESThe world's default symmetric cipher — 128-bit blocks, keys of 128, 192 or 256 bits.
- AES Key WrapA construction for encrypting one key with another, specified in RFC 3394 in 2002 and built on AES.
- AES-GCMAES in Galois/Counter Mode — authenticated encryption with associated data (AEAD) that delivers confidentiality and…
- AES3 (AES/EBU)The studio standard for sending two channels of digital audio down an ordinary balanced microphone cable.
- AES50A point-to-point link carrying 48 audio channels each way, plus clock, over an ordinary Cat5 cable — Ethernet's wiring…
- AES67The lowest common denominator that lets rival audio-over-IP systems send audio to one another.
- aewmA window manager written to be read: about a thousand lines of C showing exactly what it takes to manage windows in X, and…
- Affine cipherA monoalphabetic substitution cipher that encrypts each letter as (a·x + b) mod 26.
- Affine texture mappingTexture interpolation that ignores depth — cheap, but it makes textures visibly warp and swim, the signature look of the…
- AffirmAmerican "buy now, pay later" founded by a PayPal veteran, built around installments with no penalty fees.
- AFKAway From Keyboard — "back in a bit", one of chat culture's oldest abbreviations.
- AFLIA C64 graphics mode that pushes colour resolution to 8×1 pixels in high-resolution monochrome mode — at the cost of nearly…
- After DarkThe screensaver with the flying toasters, the 1989 Macintosh program that turned a tool against burn-in into entertainment…
- AfterpayAustralian BNPL pioneer whose "pay in four" grew so large that Block bought the company for $29 billion.
- AfterStepThe window manager that gave 1990s Linux desktops the NeXTSTEP look for people who could not afford a NeXT.
- AftertouchThe pressure you put on a key after it has already gone down, turned into a control value.
- AG GridA JavaScript component for large data tables — sorting, filtering, grouping and virtual scrolling across hundreds of…
- AGAThe Amiga's third chipset generation from 1992 — it lifted the palette to 16.7 million colours and shipped in the A1200 and…
- ageModern file encryption tool + format. Filippo Valsorda, 2019. PGP replacement for simple file crypto. Simple CLI: age -r…
- Agent (AI)An AI that doesn't just answer but takes sequential decisions with access to tools.
- Agent evalEvaluating LLM-agent performance on multi-step tasks with tools. Distinct from LLM-eval (single-turn). Benchmarks: SWE-bench…
- Agent loopThe base pattern behind every AI agent: LLM thinks → picks tool → runs → reads result → thinks again → until goal reached or…
- Agent memoryThe mechanisms that let an LLM agent remember things beyond the current context window — earlier steps in a task, facts…
- Agentic AILLM system that takes autonomous actions: plans multi-step task, calls tools, observes results, adapts plan. Distinct from…
- Agentic coding ("vibe coding")AI agents writing, running, debugging, and iterating on code on their own — you describe goals, the agent does the…
- Agentic RAGRAG where the LLM itself drives retrieval — deciding when, what and how often to search, instead of running a simple "embed…
- Agentic workflowA workflow where an LLM doesn't just answer once, but plans, uses tools, evaluates its own results, and iterates toward a…
- AgentQLAI-powered web-scraping tool. Write data-extraction queries in natural language or GraphQL-style, AgentQL handles selectors…
- Aggregate deviceA virtual audio device in macOS that merges several physical interfaces so an application sees them as one.
- Aggregate RootDDD: the single entry point into a cluster of related objects — enforces invariants and atomic updates.
- AGI (Artificial General Intelligence)Hypothetical AI that can perform any intellectual task a human can — not just specific domains.
- AgileSoftware development in short cycles with fast feedback instead of one big "waterfall" plan.
- Agnes DriscollThe US Navy's leading cryptanalyst between the wars, who broke several Imperial Japanese Navy codes.
- Agnus (Amiga)The Amiga's DMA brain — the chip that governed all memory access and housed both the Blitter and the Copper.
- Agora.ioA cloud API for real-time voice and video that apps embed instead of wrestling with WebRTC themselves.
- AGPL (Affero General Public License)GPL with a network clause: run the software as a service and you must publish the source of your modifications, even if you…
- AGSPA C64 technique for scrolling the whole screen freely in x and y, well beyond the hardware's nominal range.
- AHXAn Amiga format for synthetic chiptunes — the waveforms are computed in software on Paula, so tracks fit in a few kilobytes.
- AI (Artificial Intelligence)Computer systems that solve tasks we traditionally thought required human intelligence.
- AI directorAn overseeing system that tunes a game's pacing in real time — enemies, resources, intensity — by how the player is actually…
- AI winterThe periods when the money and the patience ran out — and researchers started calling their field something else.
- AI-completeA problem assumed to require general intelligence — you cannot solve it without having effectively solved AI itself.
- AI21 LabsAn Israeli AI company that was among the first to ship a Transformer–Mamba hybrid in production.
- AiderTerminal-based AI pair programmer — run aider in a git repo and chat with an LLM that directly edits your files and commits.
- AIFFAudio Interchange File Format — Apple's 1988 uncompressed audio format, the Mac's answer to WAV before WAV existed.
- AIGLXAccelerated Indirect GLX: Red Hat's way of giving the X server hardware-accelerated 3D effects without replacing the server.
- AIM (AOL Instant Messenger)AOL's instant messenger 1997–2017 — defined buddy lists, away messages and the iconic yellow "running man" for an entire…
- Aim assistTargeting help on a gamepad that nudges the player's aim toward targets, to offset a thumbstick's imprecision versus a mouse.
- Air bearingThe nanometre-thin cushion of air that a slider rides on above a spinning disk.
- Air controlHow much a player may steer their character while airborne — physically absurd, but essential for a platformer to feel…
- Air gapA system with no physical connection to other networks. The strongest isolation available — and considerably less absolute…
- AirbnbDisrupted the hotel industry — "any spare bedroom can be a hotel". Local-resident complaints from Barcelona, Berlin, NYC…
- AirbyteOpen-source ELT platform — 350+ connectors from SaaS APIs, databases and files into your data warehouse.
- AircallA French cloud phone system built to live inside the CRM rather than in a wall jack.
- AirPrintApple's technology for wireless printing from iPhone, iPad and Mac with no driver to install.
- AirtableA spreadsheet that thinks it's a database — column types (attached file, single select, linked record), formula fields…
- AIT (Advanced Intelligent Tape)Sony's 8 mm tape format whose signature trick was a memory chip in the cartridge itself that kept track of the contents.
- AivenA Finnish company that runs open-source databases for others — PostgreSQL, Kafka, OpenSearch and more — as a managed service…
- AixtronThe German reactor builder whose MOCVD furnaces grow the crystal layers that become LEDs, lasers and power electronics.
- AIXwindowsIBM's packaging of X11 and Motif for AIX on the RS/6000 — one of the desktops that were melted down into CDE.
- AJAX (Asynchronous JavaScript and XML)The technique of fetching data from the server in the background without reloading the whole page.
- Akai MPCThe line of samplers with sixteen rubber pads and a built-in sequencer that defined how hip-hop got made for decades.
- Akai S1000Akai's 1988 rack-mounted 16-bit stereo sampler, which became a studio standard and turned its disk format into the…
- AkamaiThe original CDN, born from an MIT mathematician's research, with servers today in almost every ISP network.
- Akamai EdgeWorkersAkamai's service for running JavaScript directly on its CDN nodes, launched in 2020.
- Akiko (Amiga)The custom chip in the Amiga CD32 that did chunky-to-planar in hardware — a shortcut around the Amiga's planar graphics.
- AkkaActor model implementation for JVM. Created by Jonas Bonér in 2009. Inspired by Erlang. Builds Akka Streams, Akka HTTP, Akka…
- AkkomaPleroma fork started in 2022 by a community frustrated with the Pleroma maintainer's politics and slow development pace…
- Al-KindiNinth-century Baghdad philosopher and mathematician who left the oldest known description of frequency analysis.
- ALAC (Apple Lossless)Apple's lossless audio codec from 2004 — what FLAC does, in Apple's own packaging.
- Alan EmtageThe Barbadian at McGill who built Archie in 1990 — usually called the internet's first search engine — because finding files…
- Alan KayCoined "object-oriented", sketched the tablet in 1972, and has spent the years since pointing out that the industry…
- Alan KonheimAn IBM mathematician on the team behind Lucifer and DES, best remembered for one sentence about the NSA.
- Alan PallerFounder of the SANS Institute, who turned security training from a conference sideline into an industry of its own.
- Alan SolomonBritish antivirus pioneer behind Dr Solomon's Anti-Virus Toolkit, one of the big names in 1990s PC protection.
- Alan TuringThe man who defined what a computer is before anyone had built one — and therefore also what one can never do.
- Alastair DennistonScottish codebreaker who ran GC&CS from its founding in 1919 and moved it to Bletchley Park.
- AlbedoA material's base colour before any lighting — the fraction of incoming light the surface reflects, with no shadows or…
- Albert GonzalezThe Secret Service informant who was simultaneously running one of history's biggest card-number thefts – more than 100…
- Alberti cipher diskTwo concentric alphabet disks from the 1460s — the earliest known polyalphabetic cipher.
- Alcatel-LucentA Franco-American telecom merger meant to create a giant that mostly produced a decade of losses, with Bell Labs in the…
- AldusThe company whose PageMaker launched desktop publishing and gave the term itself its name.
- Alec MuffettBritish security engineer who wrote the password cracker Crack in 1991 and, 23 years later, gave Facebook an address on the…
- AlembicDatabase migration tool for SQLAlchemy (Python). Mike Bayer (SQLAlchemy creator), 2010. Standard for Flask + FastAPI +…
- Alessandro AcquistiItalian economist who keeps demonstrating how little it takes for the anonymous to be named.
- Alessandro ChiesaItalian cryptographer who co-founded both Zcash and StarkWare, and who did more than most to drag succinct proofs out of…
- Alex BiryukovCryptanalyst at the University of Luxembourg behind both the slide attack and Argon2 – equally at home breaking things and…
- Alex HaldermanThe researcher who chilled RAM with canned air and showed that encryption keys survive a power cut.
- Alex IonescuWindows kernel expert who started as a teenage developer of an open-source Windows clone and ended up co-writing the…
- Alex KarpPalantir's eccentric co-founder and CEO — a doctor of philosophy running one of the world's most controversial data-analysis…
- Alex StamosThe security chief who left both Yahoo and Facebook after disagreements, then went on to study the things he had argued…
- Alexander SotirovThe exploit researcher behind Heap Feng Shui and the rogue certificate authority conjured out of an MD5 collision.
- Alexander TereshkinThe third researcher at Invisible Things Lab, who with Rutkowska and Wojtczuk went looking for places beneath the operating…
- Alexander VinnikRussian national accused of running the crypto exchange BTC-e, one of the main laundromats for proceeds from hacks and…
- Alfred MenezesWaterloo mathematician behind the MOV attack on elliptic curves, co-author of the Handbook of Applied Cryptography and one…
- Algebraic attackAn algebraic attack rewrites a cipher as a system of equations and solves it, at least on paper.
- Algebraic data type (ADT)Types built from "sum" (or) and "product" (and) — Rust enum, Haskell data, OCaml type. Enables pattern matching and…
- ALGOLThe language almost nobody ran in production, but whose ideas almost every later language inherited.
- AlgoliaSaaS search-as-a-service. Nicolas Dessaigne + Julien Lemoine (France), 2012. Fast typo-tolerant search via REST +…
- AlgorandA blockchain founded by Silvio Micali that picks block validators by cryptographic lottery rather than by burning…
- AlgorithmAn unambiguous step-by-step procedure that solves a problem.
- Algorithmic feedA feed where an algorithm decides the order and selection of posts based on what it thinks engages you most — instead of…
- Algorithmic reverbReverberation computed by a network of delays and filters rather than captured from a real room.
- AlibabaChina's e-commerce colossus — Alibaba.com (B2B globally), Taobao (C2C), Tmall (B2C), AliExpress (direct export to the West)…
- AlienwareDell's high-end gaming brand — space theme, a deranged price tag, and more LEDs than an airport.
- AliExpressConsumer-facing version of Alibaba — Chinese producers sell directly to the world. Free shipping, 2–6 week delivery…
- AlignmentGetting an AI model to do what the user actually wants — and not something unintended.
- All Your Base Are Belong To UsA line from the careless English translation of a 1991 Japanese Mega Drive game which, a decade later, became the internet's…
- All-pass filterA filter that passes every frequency at unchanged level but shifts its phase – which sounds pointless until you combine it…
- AllegroA C game programming library that gave a generation of DOS hobbyists graphics, sound and keyboard input without making them…
- Allen NewellBuilt the first programs that reasoned — then spent his life arguing that a theory of thinking has to be runnable.
- Alliant Computer SystemsA minisupercomputer whose compiler parallelised ordinary Fortran automatically across eight custom compute elements.
- Allister BrimbleThe British Amiga composer who gave Team17's early games their sound — four channels at a time.
- AllowEventsThe X request that thaws a pointer or keyboard frozen by a synchronous grab — and which, in ReplayPointer mode, lets a click…
- AlluxioA caching layer between compute jobs and storage — so Spark stops fetching the same data from S3 over and over.
- AllwinnerA Chinese maker of cheap ARM chips that powered a whole generation of bargain tablets and single-board computers.
- Alma WhittenThe researcher whose 1999 study Why Johnny Can't Encrypt showed that ordinary people could not encrypt email with PGP.
- Alonzo ChurchAnswered Hilbert's decision problem a few months before Turing, using a tool that turned out to be the ancestor of…
- Alpha blendingLaying a translucent pixel over what is already in the image, weighted by its alpha value.
- Alpha channelThe fourth channel in an image stating how transparent each pixel is — zero is invisible, maximum is fully opaque.
- Alpha testingDiscarding a pixel entirely if its alpha falls below a threshold — binary transparency that gives hard edges without any…
- Alpha to coverageTranslates a fragment's alpha into an MSAA coverage mask, approximating transparency without sorting or blending.
- Alpha-beta pruningAn optimisation of minimax that skips branches provably unable to affect the result — same answer, a fraction of the work.
- AlphaFoldDeepMind's AI that solved a 50-year-old biology grand challenge: predicting protein 3D structure from amino-acid sequence.
- AlphaGoDeepMind's Go program, which beat Lee Sedol 4–1 in March 2016, a decade earlier than experts expected.
- AlphaZeroDeepMind's AI for chess, go, shogi. Learned to play from scratch in hours through self-play. Beat the world's best chess…
- Alpine LinuxUltra-lightweight Linux distro built on musl + BusyBox + OpenRC. ~5 MB base. The de-facto standard for Docker base images.
- Alpine.jsA minimalist JavaScript framework where all the logic is written as attributes directly in the HTML. About 15 kB. Created by…
- Alps AlpineJapanese component maker behind legendary keyboard switches, rotary knobs and car audio.
- ALSAAdvanced Linux Sound Architecture — the Linux kernel's sound drivers plus the library on top, which every other piece of…
- Alt textA text description of an image, intended for anyone who can't see it. Read aloud by screen readers, shown when the image…
- Alt-dragThe X window-manager habit of moving a window by holding Alt and dragging anywhere inside it, instead of hunting for the…
- Alt-text (social media)A text description of an image for screen readers (visually impaired users). On Mastodon it's a strong community norm — some…
- alt.*Usenet's alternative hierarchy, where anyone could create a newsgroup without a vote — which is why most of internet culture…
- alt.2600Usenet's gathering place for hackers and phone phreaks, named after the magazine 2600 — and so, ultimately, after a 2600 Hz…
- alt.binariesThe branch of alt.* where Usenet stopped being a discussion forum and became a file distribution network.
- alt.configThe newsgroup where you were supposed to propose new alt.* groups before creating them, advice followed about as often as it…
- alt.folklore.computersThe Usenet group for computing history, where veterans of the punch-card and mainframe era explained how things really went.
- alt.folklore.urbanThe Usenet group for urban legends, which gave the net both fact-checking and trolling.
- alt.hackersThe moderated newsgroup with no moderator, where the entrance exam was working out how to post to it.
- alt.religion.scientologyThe newsgroup where the Church of Scientology took on Usenet — and the net learned that a discussion can't be deleted.
- alt.sysadmin.recoveryThe Usenet group where system administrators went to complain about users, managers and vendors — and kept the clueless out…
- alt.tastelessThe Usenet group for deliberately tasteless content, best remembered for its 1993 invasion of the cat lovers' rec.pets.cats.
- Alt+TabThe key combination that cycles through open windows in most-recently-used order, so a single press always takes you back to…
- AltabaThe shell left over once Verizon bought Yahoo's actual business – effectively a block of Alibaba stock wearing a different…
- Altair 8800A box of switches and lamps sold as a kit — and the starting gun for both the home computer and Microsoft.
- AltaVistaThe first search engine to index nearly the whole web, built by a hardware maker that mostly wanted to show off how fast its…
- AlteraXilinx's perpetual runner-up in programmable logic, which went into Intel and came back out again.
- AlteryxSelf-service analytics platform that let analysts build data pipelines by dragging boxes around — and charged accordingly.
- AltiumAn Australian software house whose circuit-board tools became the standard for hobbyists and smaller design shops — a…
- ALUArithmetic Logic Unit — the part of the processor that performs the basic integer and logic operations: addition…
- Always on topThe window setting that keeps one window above all the others regardless of focus: a small feature that exposes how the…
- AmazonFounded in 1994 by Jeff Bezos as an online bookstore in a garage in Bellevue. Today the world's largest e-commerce company…
- AmbarellaCalifornia fabless chip firm that moved from video-compression silicon in GoPro cameras to computer-vision processors for…
- Ambient lightA constant base illumination added to every surface to fake the indirect light a scene would otherwise lack.
- Ambient occlusionAn approximation of how much of the diffuse surrounding light actually reaches each point — creases, corners and tight…
- AmbisonicsA way of recording and storing the entire sound field around a point, independent of how many speakers it is eventually…
- AMDIntel's stubborn competitor for fifty years — at times near bankruptcy, at times the one setting the pace.
- AMD Precision BoostAMD Ryzen's opportunistic clock-frequency mechanism — the equivalent of Intel's Turbo Boost. It automatically raises the…
- AMD SEVAMD Secure Encrypted Virtualization. EPYC-only (2017+). Encrypts VM memory using AES-128 with a key managed by the AMD…
- Amdahl CorporationThe company that built IBM mainframes faster and cheaper than IBM – founded by the man who had designed them.
- Amdahl's lawSpeedup from parallelisation is bounded by the serial portion — if 10 % of the work must run serially, the max speedup is…
- American Megatrends (AMI)The vendor whose logo once flashed past on every other PC at boot, and whose code still sits underneath most motherboards.
- Ami-ExpressThe Amiga's BBS software of choice for the elite scene — known simply as /X to those who ran it.
- AmigaThe home computer that had pre-emptive multitasking and 4096 colours in 1985, and an owner who did not grasp what it had.
- Amiga 1200Commodore's last Amiga home computer: AGA graphics and a 68020, two years too late.
- Amiga 4000Commodore's last big Amiga: AGA, a 68040 and Zorro III slots in a desktop case.
- Amiga 500The Amiga-in-a-keyboard that turned the platform into Europe's games and demo machine.
- Amiga ASCIIThe Amiga scene's own branch of text art, drawn in the Topaz font with ordinary typing characters instead of the PC's block…
- Amiga CD32Commodore's CD-based games console — essentially a keyboardless Amiga 1200, and the company's final product.
- Amiga Demoscene Archive (ADA)A hand-picked archive of Amiga demos in which every entry is supposed to work and be worth watching.
- Amiga FormatThe longest-lasting British Amiga magazine — 1989 to 2000, with a floppy taped to the cover.
- Amiga Music Preservation (AMP)A database of Amiga musicians and their modules, with the same ambition for the Amiga that HVSC has for the C64.
- Amiga PowerBritish Amiga games magazine, 1991–1996, famous for giving bad games bad scores — which was not always appreciated.
- AmigaGuideThe Amiga's hypertext format for help files — clickable links between text nodes years before the web reached ordinary…
- AminetThe world's largest Amiga software archive, running since 1992 and stubbornly alive long after the platform died.
- Amit KleinIsraeli web security researcher who named two attack classes before most developers had heard of the first one.
- Amit SahaiUCLA cryptographer who co-invented attribute-based encryption and has spent two decades turning program obfuscation from a…
- amiwmAn X11 window manager that makes a Unix workstation look and behave like the Amiga's Workbench.
- Amkor TechnologyThe company that takes finished slivers of silicon and turns them into something you can solder.
- AMOLED (Active-Matrix OLED)OLED displays with a TFT behind every pixel that controls current — enables smartphones and TVs larger than 1 inch. In…
- AMOSA BASIC dialect for the Amiga built for making games, with sprite and animation commands baked in.
- Amos FiatThe Israeli computer scientist whose name is on the trick that makes almost every modern zero-knowledge proof…
- AMP (Accelerated Mobile Pages)Google's simplified HTML variant from 2015 for fast mobile pages — essentially forgotten by 2024.
- Amp modelingDigital emulation of a guitar amplifier and its speaker cabinet, so the tube amp can stay at home.
- Ampere ComputingCalifornia company building ARM processors with a very large number of cores for cloud servers.
- AmpexThe California company that turned magnetic tape into a working tool for radio, television and computing.
- AmphenolAmerican connector maker from the Bakelite age, now second-largest in the business.
- AmplitudeProduct analytics built around behaviour over time — cohorts, funnels, and which actions predict that a user will stick…
- AMQPEnterprise messaging protocol — started by JPMorgan in 2003 for banking messages. Standardised in 0.9.1 (RabbitMQ) and 1.0…
- AMR headThe first read head that sensed a magnetic field by changing its electrical resistance rather than inducing a voltage — the…
- Amstrad CPCThe home computer sold with a monitor in the box — not out of generosity, but to kill the complaint that it did not work on…
- An WangThe man who fixed core memory's read problem, sold the patent to IBM, and built an empire on word processors.
- Analog computerA machine that doesn't calculate but imitates: the quantity is a voltage or a turned shaft, and the answer is read off as a…
- Analog DevicesThe chipmaker that lives on the border between the physical world and the ones and zeros.
- Analog-to-digital converter (ADC)The circuit that measures a voltage at regular intervals and writes the answer down as an integer — the doorway between the…
- Analytical EngineA programmable computer made of gears, designed a century too early and therefore never built.
- AnalyticsCollecting + analyzing user data from web/app — pageviews, conversions, user flows, retention. Google Analytics dominated…
- AnaplanPlanning platform for budgets and forecasts that wants to replace the company's giant, fragile Excel sheet.
- AnarchieA Mac program that fused Archie search with an FTP client, so you could find a file and fetch it from the same window.
- Anchor positioningNew CSS feature (2024) that lets an element be positioned relative to another — without JS.
- Anders FoghA Danish researcher who published a "negative result" on reading kernel memory — and in doing so came within inches of…
- Anders HejlsbergHas designed four widely used languages and tools across four decades — a hit rate no other language designer comes close to.
- Andreas HülsingGerman cryptographer who made hash-based signatures practical – first XMSS, then SPHINCS+, which became the US standard…
- Andreas PfitzmannGerman computer scientist (1958–2010) at TU Dresden who turned anonymity into a research field with its own vocabulary.
- Andrei SabelfeldProfessor at Chalmers in Gothenburg and co-author of the survey that defined language-based information-flow security as a…
- Andrew "bunnie" HuangHardware hacker who broke the original Xbox's security with a home-built bus tap and has since devoted himself to building…
- Andrew AppelPrinceton professor best known first for compilers and Standard ML — and then for buying second-hand voting machines to show…
- Andrew AuernheimerAmerican troll and hacker "weev", convicted for pulling 114,000 email addresses from a public AT&T URL and later freed when…
- Andrew BoothThe crystallographer who built three computers in a basement room in London to avoid computing Fourier sums by hand.
- Andrew MyersThe Cornell professor who built Jif, a Java dialect whose compiler refuses to build your code if secret data could leak out…
- Andrew OdlyzkoMathematician who spent decades at Bell Labs and AT&T working out how hard cryptography's supposedly hard problems really…
- Andrew ToolkitThe object-oriented UI library from Carnegie Mellon's Andrew Project, built around documents where anything could be…
- Andrew YaoThe theorist who asked how two millionaires can find out which is richer without either revealing their fortune.
- AndroidGoogle's mobile operating system. Built on the Linux kernel. Acquired 2005 (Android Inc), first release 2008. ~70% global…
- Android App BundleThe publishing format that replaced the APK on Google Play — the developer uploads everything, the store builds a tailored…
- Android KeystoreAndroid's system for storing cryptographic keys so the app can use them but never read them out.
- Andromeda Software Development (ASD)Greek PC demogroup behind some of the most cinematic demos ever shown at Assembly in the 2000s.
- AndurilThe defence company Oculus founder Palmer Luckey started to build weapons the way Silicon Valley builds software.
- Andy GreenbergThe Wired reporter who was behind the wheel when hackers took over a Jeep on the highway.
- Andy Müller-MaguhnGerman hacker, long-time spokesperson for the Chaos Computer Club, elected to ICANN's board in 2000 as Europe's at-large…
- Ang CuiEmbedded-security researcher and founder of Red Balloon Security, known for turning printers and phones into intruders.
- Ange AlbertiniFile format researcher who makes files that are several things at once and draws posters explaining how.
- Angela SasseGerman-British researcher who wrote Users Are Not the Enemy in 1999 and moved the blame for bad password habits from people…
- AngelList (now Wellfound)Startup talent + investment platform — started 2010 by Naval Ravikant + Babak Nivi. 2022 pivot: jobs became Wellfound…
- Angelos KeromytisGreek-American researcher who wrote much of OpenBSD's IPsec stack and turned Bellovin's distributed firewall from a paper…
- AngularJSGoogle's first big frontend framework — it brought two-way data binding to the masses, and has been out of support since…
- Animation blendingWeighting two or more animation clips together by interpolating the bone transforms, so transitions come out smooth instead…
- Animation compressionTechniques for shrinking the data footprint of skeletal animation — curve fitting, quantisation and dropped keyframes…
- Animation crossfadeSliding smoothly from one animation clip to another by blending the poses over a short window, instead of a hard cut that…
- Animation curveA function from time to value — usually keyframes joined by tangent-controlled interpolation segments — that drives any…
- Animation eventsMarkers on an animation's timeline that fire callbacks at specific frames — a footstep sound, an enabled hitbox, a particle…
- Animation layerSeveral animations stacked so that each affects a subset of the skeleton — a base locomotion loop for the legs, an…
- Animation retargetingReplaying an animation authored for one skeleton on another with different proportions, bone to bone, so a short and a tall…
- Animation state machineA state machine whose states are animation clips or blend trees and whose transitions fire on parameters, with blended…
- Anisotropic filteringTexture filtering that samples along the direction the surface slants away in, keeping floors and roads that recede toward…
- AnkerA Chinese accessories brand that built an empire on chargers, power banks and cables — categories most others treated as an…
- Ann CaracristiAn Arlington Hall codebreaker who worked her way up to the second-highest post at the NSA.
- Ann CavoukianCanadian privacy commissioner who framed Privacy by Design, the idea that data protection belongs in the blueprint rather…
- ANN searchApproximate Nearest Neighbor — sub-linear-time vector similarity search. Trade-off: 95-99% recall for 100-1000x speedup vs…
- Anna LysyanskayaBrown University cryptographer and one half of Camenisch–Lysyanskaya, the signature scheme that makes anonymous credentials…
- Annealing phase (Midtraining)The final stretch of pretraining, where the learning rate decays toward zero while the data mixture is swapped for…
- anon.penet.fiThe Finnish pseudonymous remailer that let hundreds of thousands of people email and post to Usenet without a name — until a…
- Anonymous FTPThe convention of logging in to an FTP server as anonymous with your email address as the password — open downloads before…
- Anonymous remailerA server that accepts email, strips off the sender and passes it on — so neither the recipient nor the newsgroup can see who…
- AnotoThe Swedish company behind the digital pen that knows where it is on the page, thanks to a near-invisible pattern of dots.
- ANSI animationMoving ANSI art in which escape sequences reposition the cursor and redraw parts of the screen, with the modem's speed…
- ANSI artColourful text-mode graphics built from the IBM PC's block characters and ANSI colour codes — the login screens and menus of…
- ANSI bombA text file that abuses the terminal's ANSI parser to remap keys or vandalise the screen — the BBS era's answer to a…
- ANSI escape codeCharacter sequences beginning with ESC that tell a terminal to move the cursor, change colour or clear the screen instead of…
- ANSI musicEscape sequences that played a tune on the PC speaker when you loaded a BBS screen.
- ANSI X9.17A 1985 banking standard for key management whose random generator was built on triple DES.
- ANSI X9.23 paddingA block cipher padding scheme that fills the gap with zero bytes and puts the number of padding bytes in the last position.
- ANSI.SYSThe DOS driver that interpreted ANSI escape sequences, and so made colour, cursor movement and animated text graphics…
- AnsibleTool for automating server configuration via YAML files that describe desired state.
- AnsiLoveTool that renders ANSI and ASCII art to PNG so it can be shown on the web.
- ANSNETThe T3 backbone that carried NSFNET in the early 90s, run by a nonprofit whose for-profit subsidiary caused a fair amount of…
- AnsysThe simulation software that tells you whether the bridge holds, the wing flutters or the chip overheats before anyone…
- Ant DesignAlibaba's React component library (2015) — enterprise-focused, 50+ components, powerful data tables and forms.
- AnthropicAI safety company founded 2021 by Dario + Daniela Amodei (ex-OpenAI VP Research + VP People) + other OpenAI departures…
- Anti-aliasingSoftening the staircase along diagonal edges by blending in intermediate colours — the cure for pixels being square.
- Anti-entropyA background process in distributed databases that compares replicas and repairs differences, so they converge over time…
- Anticipating carriageBabbage's fix for addition's slowest moment: doing every carry at once instead of one column at a time.
- Antikythera mechanismA bronze clockwork from roughly 100 BC that computed the positions of the heavens — after which nobody on Earth built…
- Antivirus (AV / EDR)Software that scans for and blocks malware on your device.
- Antoine JouxFrench cryptographer with a habit of finding shortcuts everyone else had assumed weren't there.
- Antoine RossignolFrench cryptanalyst who, by the usual account, broke the Grand Chiffre during the siege of La Rochelle in 1628.
- Anton BraunThe court mechanic who handed a lavish calculating machine to Emperor Charles VI in 1727 — and died the year after.
- Antoon BosselaersBelgian cryptographer at KU Leuven and the third, usually forgotten, name behind RIPEMD-160.
- ANU NewsThe Usenet software that brought VMS machines into a network built for Unix.
- AnubisA 2000 block cipher by Paulo Barreto and Vincent Rijmen, submitted to the European NESSIE project.
- AnvilUbisoft's Assassin's Creed engine, built around climbing and crowds.
- Any-angle pathfindingPathfinding that allows edges in any direction instead of forcing the route onto the grid's 45- and 90-degree lanes.
- AnycastAn IP address that exists in many places worldwide at once — routing sends you to the nearest.
- Anycast DNSAdvertising the same IP address from many geographic locations via BGP, so each user automatically reaches the nearest node…
- AnyDeskRemote-desktop tool from former TeamViewer engineers, built around an in-house video codec for low latency.
- AOLIntroduced an entire generation to the internet over a dial-up line — and mailed out more CDs than anyone asked for.
- AOT (Ahead-Of-Time compilation)Compile to machine code before runtime. C/C++/Rust/Go are inherently AOT. The recent wave: traditionally JIT'd languages…
- Apache (httpd)The classic web server — drove the internet in the 90s and 2000s, still common on shared hosting.
- Apache AirflowPython-based workflow orchestrator — define pipelines as DAGs of tasks in code, schedule and visualise runs.
- Apache APISIXOpen-source API gateway built on OpenResty (Nginx + Lua) and etcd for dynamic config. ASF top-level project since 2020.
- Apache ArrowLanguage-independent columnar in-memory format for analytics — lets different systems share data without…
- Apache AvroBinary serialization with schema evolution. Schema embedded in file header (for file storage) or registered in Schema…
- Apache BeamA unified model for batch and stream processing where the same pipeline can run on Flink, Spark or Dataflow.
- Apache CamelJava framework for systems integration, released in 2007. Implements the patterns from the book Enterprise Integration…
- Apache CordovaThe framework that wrapped a web app in a native shell and gave it access to the camera and contacts — the original hybrid…
- Apache DruidColumnar analytics database built to answer aggregation queries over billions of rows while the data is still arriving.
- Apache IcebergOpen table format for data lakes — adds ACID, schema evolution, hidden partitioning and time travel on top of Parquet/ORC in…
- Apache NiFiDataflows you draw rather than code — drag processors onto a canvas, connect them with arrows, and data starts moving.
- Apache OzoneThe Hadoop world's answer to HDFS's namenode running out of room at a few hundred million files.
- Apache SparkUnified compute engine for big data — Matei Zaharia (UC Berkeley AMPLab), 2009, donated to ASF in 2013. Much faster than…
- Apache ZooKeeperThe boring service that tracks who the leader is, who is alive and what the configuration says — so the rest of the cluster…
- Aperture cardA punched card with a cut-out window holding a chip of 35 mm microfilm — the card indexes, the film carries the image.
- API (Application Programming Interface)A structured way for two programs to talk to each other.
- API 500 seriesA module format for preamps, EQs and compressors, in which narrow cards slot into a shared chassis that provides the power.
- API keyString that identifies your application to an API — like a password, but for programs.
- ApigeeThe company that sold the idea of an API as a product, complete with keys, quotas and billing, and was then sold to Google.
- APKAndroid's installation file — fundamentally a zip archive holding code, resources and a signature.
- APNThe name telling the network which exit in the operator's network mobile data should take — Access Point Name.
- APNsApple's push service — the only route by which a server can wake an app on an iPhone.
- Apogee SoftwareThe Texas publisher that worked out you could give away the first third of a game and sell the rest by mail order.
- Apollo ComputerThe Massachusetts workstation pioneer that got to "the network is the computer" first — and lost to Sun, which said it…
- Apollo Display ManagerThe window system of Apollo's workstations from 1981, three years ahead of X and the Macintosh, in which every window was a…
- Apollo ServerThe most popular GraphQL server for Node.js — started the Apollo stack (Apollo Client + Server + Federation). Built by the…
- App Router (Next.js)Next.js routing system launched in 13 (Oct 2022). Replaces Pages Router. File-system-based: /app/posts/[slug]/page.tsx =…
- App StoreApple's store and the only sanctioned way to install apps on an iPhone — the model that created the app economy and then…
- App Tracking TransparencyThe prompt asking "allow this app to track you?" — Apple's 2021 change that blew a hole in the advertising industry's…
- app_server (BeOS)The BeOS window system: a single server process that owns the screen, draws frames and text for every application and talks…
- app-defaultsThe directory with one resource file per X application, named after the program's class, where the developer put the default…
- AppDynamicsA commercial APM platform that instruments the application from the inside and shows where the response time actually went.
- Appearance ManagerThe Mac OS 8 component that drew windows, buttons and menus centrally and gave the Mac its grey, bevelled Platinum look.
- Append-only logData structure where entries are only-added, never modified or deleted. Tamper-evident: any modification is detectable via a…
- AppImagePortable Linux app format — a single .AppImage file that runs directly without installation (chmod +x and run).
- AppleHas reinvented itself three times — the home computer, the graphical computer, and the phone that became the computer — and…
- Apple IIThe machine that turned Apple into a company and the spreadsheet into a reason to buy a computer.
- Apple LisaApple's first graphical computer: technically ahead of its time, priced like a car, and buried in a landfill in Utah.
- Apple menuThe menu behind the apple at the far left of the Macintosh menu bar, the system's own corner of it since 1984.
- Apple SiliconApple's own ARM-based chips — M1 (2020), M2, M3, M4. Replaced Intel on Mac.
- AppleLinkApple's own online service for dealers and developers — and the indirect ancestor of America Online.
- Application context (Xt)Xt's container for everything that belongs to a program rather than to a window, display connections, event queue, timers…
- Applied CryptographyBruce Schneier's 1994 book that handed a generation of programmers both the protocols and the source code, right in the…
- Applied MaterialsThe equipment maker behind nearly everything in a chip fab except the lithography itself.
- appresThe tool that shows which X resources a program would get if it started right now, given its class and instance name.
- Apricot ComputersThe British PC maker that ran MS-DOS but refused to be IBM-compatible, and learned the hard way why everyone else gave in.
- APT (Advanced Package Tool) (Advanced Package Tool)Debian/Ubuntu's package manager — apt install nginx. Handles dependencies, repositories, GPG signing on top of low-level…
- APT (Advanced Persistent Threat) (Advanced Persistent Threat)Sophisticated threat actor — typically state-sponsored — that gets in, lies low for months, exfiltrates data systematically.
- aptXThe audio codec Android phones and wireless headphones negotiate when both sides have paid Qualcomm.
- AquaMac OS X's interface style from 2000, with blue gel buttons, traffic lights in the window corner and a Dock, which Steve…
- AR (Augmented Reality)Overlay of digital information on the physical world — either via camera feed (smartphone) or transparent display (headset).
- ARA (Audio Random Access)An extension to VST, AU and AAX that lets a plug-in read the whole audio file on the timeline instead of only the buffer…
- ArangoDBA multi-model database doing documents, graphs and key-value in one engine — and querying all of it with a single language.
- Arbitron (Usenet)Usenet's ratings: a script and a monthly report that estimated how many people read each newsgroup.
- Arbor NetworksThe company whose boxes sit inside ISP networks and see DDoS attacks coming before the customers notice anything.
- ARCAdaptive Replacement Cache — cache eviction algorithm that dynamically balances recency (LRU) and frequency (LFU). IBM paper…
- ARC (archive format)The archive format that first bundled and compressed files in one step on MS-DOS — then lost everything in a lawsuit the BBS…
- ARC (Automatic Relay Computer)The relay machine two people built in a basement room at Birkbeck for a fraction of what Manchester and Cambridge spent…
- Arcade gameCoin-operated games, built to be hard enough to empty your pocket in three minutes but fun enough that you queued up again.
- Arch LinuxDIY distribution with rolling release — always bleeding edge. Pacman package manager. AUR (Arch User Repository) has…
- Archetype (ECS)In an entity component system, the unique set of component types an entity carries — all entities with exactly the same set…
- ArchieThe internet's first search engine: a database of the file names on the world's open FTP servers.
- ARCoreGoogle's augmented reality framework for Android — the answer to Apple's ARKit, built on the remains of Project Tango.
- Arctic WolfA security operations centre on subscription: the company supplies the analysts the customer was never going to find time to…
- Ardent ComputerThe Titan graphics supercomputer — vector power and 3D rendering in one box, built for scientific visualisation.
- Ardit FeriziA Kosovar hacker who became the first person in the US convicted of terrorism over a data breach.
- ArdourThe DAW that proved studio-grade multitrack recording could be done as free software on Linux.
- ArduinoItalian open-source MCU platform — made hardware hobbyism mainstream in the 2000s.
- Area lightA light with real surface area and size instead of a point, giving soft shadow edges and realistic reflections.
- AreafixFidoNet's mail robot for subscribing to and dropping echomail conferences.
- Areal densityBits per unit area on a platter — the hard disk's headline progress metric, the product of linear density and track density.
- Arena allocatorThe allocation strategy where you take one large block of memory, hand out pieces of it by moving a pointer forward, and…
- ARGB visualThe 32-bit X11 visual whose fourth byte is an alpha channel, so a window can be translucent per pixel — provided a…
- ArgoFour Kubernetes-native projects under one name, one of which — Argo CD — became the default way to do GitOps.
- Argo CDThe most used GitOps tool for Kubernetes: a controller that runs in the cluster, reads declared applications from git repos…
- Argo RolloutsKubernetes controller that replaces Deployment with canary, blue-green, and automated analysis.
- Argon2Modern password hashing algorithm — winner of the Password Hashing Competition 2015 and OWASP-recommended.
- argparsePython's built-in module for command line arguments — declare the flags and get parsing, type conversion and --help for free.
- ArgumentValue passed into a function at the call site — add(2, 3) has the arguments 2 and 3.
- Ari JuelsAmerican cryptographer behind honeywords, proofs of retrievability and one of the earliest proof-of-work proposals.
- ARIA (Accessible Rich Internet Applications)Attributes that add accessibility info to HTML elements that don't say enough on their own.
- Arista NetworksThe switch maker that took data centres away from Cisco using off-the-shelf chips and a Linux that was actually Linux.
- ArithmometerThe first calculator manufactured in series and available to order, which turned computation from a craft into a product.
- ARJThe DOS archiver that split big archives into floppy-sized volumes — and so became the default for anything moved 1.44 MB at…
- Arjen LenstraDutch mathematician who has spent four decades measuring exactly how hard RSA is to break, usually by breaking it.
- Arkane StudiosThe French specialists in the "immersive sim" — games where the level is a box of problems and the player picks the tools.
- ARKitApple's augmented reality framework, launched in 2017 — it made AR available on hundreds of millions of phones overnight.
- ARMProcessor architecture that powers basically every smartphone, Apple Silicon Mac and Raspberry Pi.
- ArmisIsraeli-founded security company that maps every connected device on a network — without installing an agent on any of them.
- ARMMA Usenet moderation program that ran amok in news.admin.policy in 1993 and handed the net the word "spam".
- Arne BeurlingReconstructed a German cipher machine he had never seen in two weeks with pencil and paper — then refused to explain how.
- ARP (Address Resolution Protocol)The protocol that finds the MAC address belonging to an IP address on the local network.
- ARP cacheTable in the OS kernel that maps IPv4 → MAC. Populated by ARP requests (broadcasts) or static entries.
- ARP InstrumentsAmerican synthesizer maker that was Moog's main rival through the 1970s, and that was sunk by a guitar synth.
- ARP poisoningL2 attack: attacker on same LAN sends fake ARP responses → victim's ARP cache maps gateway IP to attacker's MAC. All…
- ARP spoofingAn attack where the attacker sends forged ARP replies on a local network to associate their own MAC address with someone…
- ARPANETThe packet-switched research network that became the internet.
- ArpeggiatorA device or algorithm that plays the notes of a chord in sequence at a rapid, user-controlled rate, producing a…
- ArpeggioCycling a single channel rapidly through the notes of a chord so the ear fuses them into one — chip music's classic…
- ArrayAn ordered collection of elements stored in one contiguous memory block — you index by number.
- Art of CodingThe campaign to get the demoscene recognised as living cultural heritage, one country at a time, with UNESCO as the end goal.
- Art packA monthly package of ANSI and ASCII art that art groups released on BBSes, complete with a member list and an nfo.
- Arthur BurksA philosopher who became an ENIAC engineer and then co-wrote the report that drew the blueprint for the modern computer.
- Arthur ScherbiusThe German engineer who patented Enigma in 1918 and died before the machine became both war-winning and broken.
- Artificial intelligenceThe umbrella term for making machines do things that otherwise require human judgement — a field that has changed meaning…
- aRtsThe sound server of KDE 2 and 3, which began in the late 1990s as a modular software synthesizer and ended as the program…
- Artur EkertPolish-born physicist whose E91 protocol bases the security of quantum key distribution on entanglement rather than on…
- ArturiaA French company that made its name emulating classic synths in software, then started building affordable analogue synths…
- Aruba NetworksEnterprise wireless run centrally from a controller, and these days HPE's networking division.
- Arvind NarayananComputer scientist who showed that "anonymized" data rarely is, and has treated every new technology with the same suspicion…
- AS path prependingWriting your own AS number into the path several times so it looks longer, in the hope that the world will pick some other…
- AS-REP roastingAccounts with Kerberos pre-authentication disabled hand out a packet encrypted with their password to anyone who asks. No…
- AsanaCloud service for work and project management, built by two early Facebook engineers out to cure their own meeting fatigue.
- Ascend CommunicationsThe company whose access servers answered a large share of the 1990s' dial-up internet calls.
- ASCII7-bit character encoding from 1963 — 128 characters: letters, digits, symbols, control characters.
- ASCII artPictures built from the printable ASCII characters — from lineprinter pin-ups to Usenet signatures and NFO files.
- ASCIImationAnimation made purely from ASCII characters, frame by frame, with no colour or block graphics.
- AsciiquariumAn aquarium in your terminal, drawn entirely in ASCII — fish, sharks, ducks and a castle on the seabed.
- AsconA lightweight family for authenticated encryption and hashing, chosen by NIST in 2023 as the standard for small devices.
- AsepriteThe pixel-art editor that became the de facto standard for sprite animation — paid, yet with its source sitting openly on…
- Ashton-TateThe software house behind dBASE, the database every PC office of the 1980s learned to drive with dot commands.
- ASIC (Application-Specific Integrated Circuit)Application-Specific Integrated Circuit — a chip designed and manufactured for a single specific task, rather than being…
- ASIOAudio Stream Input/Output — Steinberg's driver interface that lets audio software on Windows talk straight to the sound card…
- ASIO4ALLA free, vendor-neutral driver that puts an ASIO interface on top of Windows' own audio drivers.
- Ask JeevesThe 1990s search engine where you asked a cartoon butler questions in plain English.
- ASM-OneHiSoft's assembler package, which followed the home computers from the ZX Spectrum to the Atari ST and Amiga and was the…
- asm.jsStrict subset of JavaScript optimized for AOT compilation. Mozilla, 2013. Type annotations via codes (x|0 = int, +x =…
- ASMLThe Dutch firm with a near-monopoly on the machines that print the world's most advanced chips.
- ASN (Autonomous System Number)A unique number for every "autonomous system" on the internet — operators' networks are identified by their ASN in the BGP…
- ASP.NETMicrosoft's web framework family. Classic ASP.NET (Web Forms, MVC, Web API) on .NET Framework, then ASP.NET Core on…
- ASP.NET CoreThe rewrite of ASP.NET that made Microsoft's web stack cross-platform, open and fast.
- ASPA (Autonomous System Provider Authorization)A signed RPKI object in which an autonomous system enumerates its upstream providers. Meant to stop the kind of mistake ROA…
- aspect-ratioA CSS property that lets an element maintain a set aspect ratio (e.g. aspect-ratio: 16/9) regardless of width. It eliminates…
- AspectJAspect-Oriented Programming extension to Java. Xerox PARC, Gregor Kiczales and others, 2001. Define "aspects" that cross-cut…
- ASR-33Teletype's cheap 1963 teleprinter — the machine that put ASCII in everyone's hands and gave Unix its tty.
- ASRC (asynchronous sample rate converter)A converter that takes in digital audio on one clock and hands it out on another, with no requirement that the two clocks…
- ASRockASUS's budget label that grew up into a competitor with its own, occasionally peculiar, taste.
- Assembly (demoparty)Finland's big summer party, started in 1992 by demogroups and since grown into one of the largest computer events in the…
- Assembly languageHuman-readable form of CPU instructions — one step above machine code.
- AssertionA statement in code about what must be true — if it isn't, the program crashes.
- Asset bundleA package of pre-built game resources — models, textures, sounds, prefabs — loaded at runtime instead of being baked into…
- Asset pipelineThe toolchain that turns source formats — PSD, FBX, WAV — into engine-ready runtime formats through import, processing…
- Associative arrayData structure mapping keys to values. Different names per language: dict (Python), hash (Ruby/Perl), HashMap (Java/Rust)…
- AST (Abstract syntax tree)A tree representation of source code structure with the syntactic noise stripped away.
- AST ResearchCalifornian company that started out selling add-in cards for the IBM PC and ended up one of the world's largest PC makers…
- AstroModern web framework focused on content-heavy sites — "zero JS by default".
- Astro IslandsAstro's "Islands Architecture" — the page is HTML by default, but individual components can "hydrate" on the client with…
- AstrolabeThe night sky folded into brass — an analog computer that solved problems of astronomy and timekeeping long before the…
- AstroturfingStaging a grassroots movement that doesn't exist. The name comes from the AstroTurf brand — fake grass. The client is a…
- ASUSTaiwanese manufacturer that started with motherboards, invented the netbook more or less by accident, and now sells…
- async / awaitSyntax that lets you write asynchronous code that looks synchronous.
- Async computeLets a GPU run compute work at the same time as graphics work, on separate queues, to fill the gaps where the shader units…
- AsynchronousCode that doesn't block execution while a slow operation (I/O, network, timer) is in progress. Frees the thread for other…
- Asynchronous reprojectionWarping the last rendered image to the freshest pose in a separate, high-priority GPU pass, so the headset always has a new…
- At EaseApple's simplified 1992 replacement for the Finder, built for schools and children who were not to be trusted near the…
- AT Protocol (atproto)The protocol behind Bluesky. Built around an idea ActivityPub lacks: portable identity — your account is a DID that you keep…
- At-least-once deliveryMessaging guarantee: a message is delivered at least once, sometimes more. Consumers must handle duplicates (idempotent…
- At-most-once deliveryMessaging guarantee: a message is delivered at most once (can be lost, no duplication). "Fire-and-forget". Classic UDP…
- AT&TThe American telephone monopoly that owned Bell Labs, gave the world Unix almost by accident and was broken up in 1984.
- Atalla BoxMohamed Atalla's early-1970s encryption box for bank PINs, widely regarded as the first hardware security module.
- Atanasoff-Berry ComputerThe first electronic digital computing device, built in an Iowa basement, scrapped in 1948 by people who did not know what…
- AtariThe company that created the games industry, lost it in a year, and has since lived on as a brand passing between owners.
- Atari 2600The console that made the cartridge standard — with so little memory that the programmer had to draw the picture line by…
- Atari 8-bit familyAtari's line of home computers from 1979 — 400, 800, XL and XE — built around custom chips that were years ahead of the…
- Atari Falcon030Atari's last computer, from 1992 — a 68030 machine with a built-in signal processor that arrived just as everyone stopped…
- Atari STThe Amiga's arch-enemy, built in a year by the man behind the Commodore 64 — and the computer that furnished a generation of…
- ATASCIIThe Atari 8-bit computers' own take on ASCII, with graphics characters that made it raw material for text art on Atari BBSes.
- AtbashThe alphabet read backwards: first letter becomes last, second becomes second-to-last, and so on, with no key whatsoever.
- AteaThe Nordics' largest seller of IT infrastructure — the name on the invoice when a municipality buys laptops, licences or a…
- Athena Widgets (Xaw)X11's free bundled widget set: flat, spartan, and equipped with a scrollbar that has confused people since the 1980s.
- AtherosA Stanford spin-off whose Wi-Fi chips ended up in a large share of the world's routers and became the Linux crowd's…
- ATI TechnologiesThe Canadian graphics company behind Radeon, and the only one of the 1990s' many challengers that kept pace with Nvidia well…
- ATIPAbsolute Time In Pregroove — the timecode and disc-info scheme frequency-modulated into a CD-R's wobbling groove.
- AtlantisRuns Terraform from the pull request instead of from somebody's laptop. The plan is posted as a comment and thereby becomes…
- AtlassianThe Australian company whose tools — Jira, Confluence, Bitbucket — structure the work of a large share of the world's…
- AtmelA memory maker that happened to produce AVR — the microcontroller in almost every Arduino and therefore in a generation of…
- Atmospheric scatteringHow sunlight is scattered by the air's molecules and particles — the reason the sky is blue by day and red at sunset.
- Atom (X11)A 32-bit number the X server hands out in place of a string, so names don't have to cross the network again and again.
- Atom FeedWeb syndication format. RFC 4287 (2005). IETF's answer to RSS's chaotic version history (RSS 0.9, 0.91, 1.0, 2.0). Strict…
- Atomic operationAn operation that runs as an indivisible unit — either fully done or not started, never halfway.
- Atomic operationsOperation completed as a unit — either entirely or not at all. Crucial in concurrent systems to avoid data races without…
- AtosA French IT group that bought its way to scale, ran the Olympics' IT and then nearly drowned in its own debt.
- ATRACThe MiniDisc codec that squeezed a CD into a quarter of the space — Sony's answer to a pocket-sized optical disc that…
- Attack and releaseThe two time constants that decide how quickly a compressor clamps down once the signal crosses the threshold, and how…
- Attack surfaceThe sum of all the points where an attacker could potentially get into a system — open ports, API endpoints, login pages…
- AttentionThe core mechanism in transformer models — each token looks at all others and decides how relevant they are to the context.
- Attention mechanismNeural mechanism for focusing on relevant parts of the input. Bahdanau et al. (2014) introduced it for translation. Vaswani…
- Attention sinkTransformer models dump a disproportionate share of their attention on the very first tokens of the sequence, regardless of…
- AttestationCryptographic claim about system state, software, or workload — signed by a trusted party. Hardware attestation (TPM, Intel…
- Attract modeWhat an arcade cabinet does when nobody has fed it a coin: plays itself, shows the high-score table and begs for attention.
- Attribute clashThe ZX Spectrum limitation where each 8×8 cell holds only two colours, so overlapping objects bleed into each other's hues.
- Attribution ReportingA browser API in which the browser itself connects an ad click to a later purchase, and hands out the result so coarsely and…
- ATX (Advanced Technology eXtended)The dominant PC form-factor spec since 1995 — motherboard 305 × 244 mm, standardised IO shield, power rails, PCIe slot…
- AudacityThe free audio editor installed on nearly every computer whose owner has ever had to trim a podcast.
- Audio callbackThe function the audio driver calls whenever the next buffer needs filling — and which must never be late.
- Audio feedbackThe microphone picks up the speaker, which amplifies the microphone, which picks up the speaker — until the whole chain…
- Audio fingerprintingA compact summary of a recording that lets a system identify the song from a few seconds of noisy audio.
- Audio interfaceThe external sound card of the home studio: the box where microphones and instruments become numbers and numbers become…
- Audio jack3.5mm connector for headphones and microphone — analog audio signal since the 1960s.
- Audio occlusionMuffling a sound whose path to the listener is blocked by geometry — usually a low-pass filter plus a volume cut, triggered…
- Audio UnitApple's plugin format for audio effects and software instruments, built into Core Audio on macOS and iOS.
- Audio-to-MIDIListening to a recording and writing out which notes were played, when and how hard, as MIDI notes.
- AudioKitAn open-source Swift framework that turns synthesis and audio processing on Apple platforms into a few lines of code.
- AudioWorkletThe part of the Web Audio API where you write your own audio processing in JavaScript or WebAssembly, run on the browser's…
- Audit logImmutable log of who did what and when — for forensics and compliance.
- Auditory maskingA loud sound renders quieter sounds nearby inaudible, even though they are still present in the signal.
- Auguste KerckhoffsThe Dutch linguist who in 1883 wrote down six rules for military cryptography — one of which still governs the entire field.
- Augustus De MorganThe logician whose two laws every programmer uses silently each time a condition gets inverted — and who was also Ada…
- AUR (Arch User Repository)Arch Linux's community-driven package repository. It doesn't contain packages but PKGBUILD recipes — build scripts that…
- AurealPositional 3D audio that nearly beat Creative — until legal bills sank the company.
- aus.*Australia's national Usenet hierarchy, for everything that only concerned people on the far side of the planet.
- Auth0The best-known managed IdP — login buttons, OIDC flows, social login without writing a line of auth code yourself. Acquired…
- Authenticated encryptionEncryption that also lets the recipient detect whether anyone altered the ciphertext.
- Authentication (AuthN)Proving who you are. The login flow, basically.
- Authentication tagThe short value that shows a message was not altered and came from someone holding the key.
- Authorization (AuthZ)Deciding what an already-authenticated user is allowed to do.
- Authorization holdAn amount the issuer ring-fences on the card account at the time of purchase, before any money has actually moved.
- AuthyA two-factor app that early on dared what Google Authenticator wouldn't: sync the codes across devices and back them up in…
- Auto-exposureThe renderer measures the scene's average brightness and adjusts exposure per frame, so that a dark cave and a sunlit street…
- Auto-raiseThe window manager setting that lifts the focused window to the top of the stack after a moment, so focus can follow the…
- Auto-TunePitch correction meant to quietly fix bum notes, which instead became one of the most recognisable sounds in pop music.
- AutoConfigThe Amiga's protocol for letting expansion cards assign themselves memory addresses at boot — plug-and-play a decade before…
- AutodeskPut the drafting table inside the personal computer, then let the file format keep the customers there.
- AutoencoderNeural architecture that learns to compress input into a latent vector (encoder) and reconstruct input from it (decoder)…
- AutoGenMicrosoft's open source multi-agent framework — agents converse with each other to solve tasks. Started by MS Research in…
- Autokey cipherA polyalphabetic cipher whose key is extended with the plaintext itself, so it never repeats.
- Automatic Document FeederThe mechanism that draws a stack of paper past the scan head one sheet at a time, so multi-page copies and scans run without…
- Automatic double tracking (ADT)Feeding a vocal into a second tape machine with a few wobbling milliseconds of delay, so one take sounds like two.
- Automation (DAW)Recorded movements of controls — volume, pan, effect parameters — that play back along with the music.
- AutomatticThe commercial company wrapped around WordPress, which also happens to own Tumblr.
- AutomergeCRDT library from Ink & Switch / Martin Kleppmann — focus on JSON-like structure with full revision history (for "git for…
- AutoMod (Reddit)Reddit's built-in automoderator bot that applies rule-based actions to posts and comments — removing, flagging, or filtering…
- Autonomous system number (ASN)A unique number that identifies an autonomous system — a collection of networks under a common administrative control and…
- AutonomyBritish search company whose 2011 sale to HP became one of tech's most expensive mistakes and a decade-long courtroom saga.
- AutoscalingAutomatically start more or fewer instances based on load.
- AutotilingAutomatically picks the correct tile graphic for each cell based on which neighbours it has, so edges and corners fit…
- AutovacuumA PostgreSQL background process that automatically runs VACUUM and ANALYZE when a table has accumulated enough dead rows. On…
- AutoYaSTSUSE's system for fully unattended installation — an XML profile describes the whole machine, SUSE's answer to Kickstart.
- Aux sendA tap on a mixer channel that sends a copy of the signal to a shared bus, usually feeding an effect many channels have in…
- Auxiliary-loss-free load balancingBalancing the load between experts in an MoE model with an adjustable bias term rather than a penalty in the loss function.
- AV1The royalty-free video codec the industry banded together to build in order to stop paying licence fees for H.265.
- Avalanche effectOne bit in should change about half the bits out — otherwise the construction is leaking structure.
- AvastCzech antivirus company that turned free protection into a mass-market product, then demonstrated what free can cost.
- AvatarThe image that represents you online — from a Sanskrit descent of a god to a 128×128 square next to your username.
- AVATAR (terminal protocol)A leaner alternative to ANSI escape codes for BBS graphics, designed so coloured menus would arrive before the caller lost…
- AvayaLucent's old business phone systems, spun off in 2000 and locked in a near-permanent struggle with its debt ever since.
- AVB (Audio Video Bridging)A set of IEEE standards that makes ordinary Ethernet predictable enough to carry audio and video with guaranteed latency.
- AVG TechnologiesThe other Czech free antivirus, which was eventually bought by the first one.
- Avi RubinJohns Hopkins professor whose 2003 teardown of Diebold voting machines made election technology a security issue in the US.
- Avi WigdersonIsraeli complexity theorist who showed that any NP statement can be proven without revealing anything else, and received the…
- AVIF (AV1 Image File Format)Modern image format built on the AV1 video codec. Alliance for Open Media (Google, Netflix, Apple, Amazon and others), 2019…
- Avishai WoolThe researcher who measured how badly firewalls are actually configured — and got numbers nobody wanted.
- AVL treeThe first self-balancing binary search tree — Adelson-Velsky & Landis (1962). Each node keeps the height difference between…
- AVX (Advanced Vector Extensions)Intel's SIMD instruction set with 256-bit registers. Introduced in Sandy Bridge 2011. AVX2 (Haswell, 2013) added integer…
- AVX-512A set of 512-bit SIMD instructions (Intel, later AMD) that process large data vectors in a single sweep. Powerful for…
- Award SoftwareThe third big BIOS vendor, whose code booted half the clone PCs of the 1990s before Phoenix swallowed it.
- Away messageThe automatic "I'm not here" message from the instant-messaging era (AIM, MSN, ICQ) — often filled with song lyrics, quotes…
- awesomeA tiling window manager that started as a dwm fork and became a Lua program with window management built in.
- AWKA pattern-driven text-processing language from 1977, named after Aho, Weinberger and Kernighan.
- awmThe Ardent Window Manager: uwm with title bars, icons and small buttons bolted on, written in 1988 at a maker of graphics…
- AWQActivation-aware Weight Quantization — 4-bit post-training quantisation that protects the "important" weights based on what…
- AWS (Amazon Web Services)The world's biggest cloud provider (~30 % market share in 2024). 200+ services, 35+ regions. Born from Amazon's own internal…
- AWS CDK (Cloud Development Kit)Define AWS infrastructure in TypeScript, Python, Java, C# or Go. cdk synth compiles the code into CloudFormation templates…
- AWS CloudFormationAWS-native Infrastructure-as-Code. JSON/YAML templates describe resources; CloudFormation creates/updates them as a "stack"…
- AWS CloudHSMA dedicated HSM in Amazon's data centre where the customer, not Amazon, holds the keys.
- AxcelisAn American company that does one thing — firing in the dopant atoms that turn silicon into a transistor.
- Axe-FxFractal Audio's rack processor, which took digital amp simulation from the bedroom to the arena stage.
- Axis CommunicationsThe company from Lund, Sweden, that put a camera straight onto the network in 1996 and turned the CCTV camera into a…
- AY-3-8910General Instrument's three-channel sound generator from 1978 that gave voice to the ZX Spectrum, Amstrad CPC, MSX and Atari…
- Azimuth recordingTilts adjacent write tracks at opposite angles so they can sit edge to edge with no guard band and still not interfere.
- Aztec CodeTwo-dimensional barcode with a square bullseye at its centre, built to pack tightly with no blank margin around it.
- Azure (Microsoft Azure)Microsoft's cloud — ~25 % market share. Dominates in Office 365 shops thanks to native integration with Entra ID (formerly…
- Azure FunctionsMicrosoft's serverless FaaS. Launched 2016, Microsoft's answer to AWS Lambda. Supports C#, JavaScript, Python, Java…
- Azure PipelinesThe CI/CD half of Azure DevOps — build and deploy pipelines defined in YAML, with free agents for open source.
- Azure Service FabricMicrosoft's platform for distributed microservices — built internally for a decade before it was released publicly in 2015.
- BGP Add-PathAn extension letting BGP advertise several paths to the same prefix rather than only the best one. Sounds like a detail…
- Google App EngineGoogle's original PaaS (2008) — deploy a Python/Go/Java/Node app without thinking about servers; autoscales from 0 to…
- PDS (atproto)Personal Data Server — AT Protocol concept where each user owns their own "data server" (posts + likes + follows). Bluesky's…
- The ABA problemA thread reads the value A, gets interrupted, and when it returns the value is A again — but in between it was B, and the…
- Twinscan (ASML scanner family)ASML's exposure scanner family — twin chuck design (one wafer is exposed while the next is measured) for double the…
B
- Amazon BedrockAWS managed service for foundation models — one API across Claude, Llama, Mistral, Titan, Cohere, Stable Diffusion and more…
- B NewsSecond-generation Usenet software, sturdy enough to let the network grow from a few dozen machines to thousands.
- B-treeBalanced search tree designed for block-based storage — each node maps to a disk page and holds hundreds of keys, so a…
- B&R Industrial AutomationAustrian automation firm behind Automation Studio and the POWERLINK real-time network, part of ABB since 2017.
- B1FFUsenet's archetypal teenage newbie: writes in capitals, swaps letters for digits and ends every sentence with an exclamation…
- b3taBritish comedy site from 2001 whose weekly image-manipulation contest supplied the internet with animated GIFs long before…
- BaanDutch ERP vendor that was SAP's most dangerous European rival — until someone looked closely at the books.
- BaaS (Backend as a Service)A ready-made backend as a service: auth, database, file storage, push and serverless functions behind an SDK. The frontend…
- Babbage's Mechanical NotationA sign language for stating what every part of a machine does and when it does it — Babbage's own favourite discovery, and…
- BabelJavaScript transpiler. Made ES6+ (arrow functions, destructuring, async/await) possible on older browsers by transpilation…
- Babington PlotA 1586 conspiracy against Elizabeth I that was exposed by cryptanalysis and cost Mary, Queen of Scots her head.
- Babylon.jsMicrosoft-backed 3D engine for the web — more "game-engine-like" than Three.js, with an inspector tool, playground, physics…
- Back-face cullingSkipping the triangles that turn their back to the camera before they cost anything to draw.
- Back/forward cache (bfcache)A browser optimization that saves a whole page in memory (a "frozen" snapshot with its JS state) when you navigate away, so…
- BackblazeBackup and storage company better known for its hard drive statistics than for anything it sells.
- Backbone cabalThe informal club of administrators at the big Usenet sites who, through the 1980s, effectively decided which newsgroups got…
- Backbone.jsThe minimal MVC library that gave structure to the jQuery era — models, views and a router in under 2,000 lines.
- BackdoorA hidden access path into a system — either deliberately planted by an attacker or (controversially) demanded by a state.
- backdrop-filterCSS property that applies a filter — almost always a blur — to whatever sits behind an element rather than to the element…
- BackendThe part of a system that runs on the server — what the user doesn't see directly.
- Background writerThe PostgreSQL process that writes modified pages out of the buffer cache in advance, so a query needing a free buffer…
- BackhaulThe link between a base station and the operator's core network — the invisible part that decides whether the mast actually…
- Backing store (X11)An optional service where the X server keeps whatever other windows cover up, so the application doesn't have to redraw it…
- BackpressureWhen the consumer is slower than the producer — strategies to keep input buffers from growing unbounded and crashing the…
- Backpressure (ops)The mechanism where an overloaded system signals upstream "slow down" instead of collapsing under more work than it can…
- BackpropagationThe algorithm that trains neural networks — runs error backwards through the network and adjusts every weight.
- Backside power deliveryRouting power to the transistors through the back of the silicon instead of squeezing it in among the signal wires on top…
- BackstageOpen source developer portal from Spotify. CNCF Incubating 2020. Central place for software catalog, service templates…
- BackupCopies of data you can restore if the original is destroyed.
- Baconian cipherEach letter becomes five symbols drawn from A and B, which are then hidden in ordinary text as two nearly identical…
- Bad lineThe scanline where the C64's video chip grabs the memory bus and leaves the processor with a third of its cycles.
- Bad sectorA disk sector that can no longer hold data reliably — silently remapped to spare sectors until they run out.
- BadaSamsung's own smartphone OS from 2010 that never threatened Android and melted into Tizen in 2013.
- Badger Badger BadgerThe 2003 Flash loop with twelve dancing badgers, a mushroom and a snake that interrupts the whole thing. It defined an…
- BahnhofA Swedish ISP from Uppsala that turned privacy into a business model and runs a data centre inside a Cold War bunker under…
- BaichuanAI lab founded by Sogou's former CEO Wang Xiaochuan, which after a fast model race pivoted toward medical AI.
- BaiduChina's dominant search engine, whose founder patented link analysis before Google existed.
- Baked lightingLighting computed ahead of time in a tool and stored in textures or probes, so that runtime only looks up finished values…
- Balanced audioTwo signal conductors with equal impedance to ground, so interference that hits both can be subtracted out at the receiving…
- Ball-socket jointA joint that pins two bodies at a single point but lets them rotate freely about all three axes, like a shoulder or hip.
- Ballistic Research LaboratoryThe US Army's computing laboratory in Maryland, which ordered most of the early American computers for one reason: the…
- Balloon hashingA password hash that makes attackers spend as much memory as honest users do.
- BanburismusTuring's method for guessing Enigma's rotor settings by counting how often two ciphertexts happened to share a letter in the…
- Band printerA line printer whose type sits on a thin looping steel band — the chain printer's quieter, sharper-printing cousin.
- Band steeringA WiFi feature where the access point steers clients to the most suitable frequency band (2.4 / 5 / 6 GHz) instead of…
- Band-pass filterA filter that passes a band around a centre frequency and attenuates everything below and above it.
- BandcampDirect sales platform for indie music — fans pay artists directly, often "name your price".
- BandingThe visible steps in a smooth gradient — the sky in a video looking as though it were painted in stripes.
- BandwidthHow much data per second passes through a network link. Measured in Mbps or Gbps.
- Bang pathThe UUCP-era email address, in which the sender spelled out every machine on the way to the recipient, separated by…
- Bank Select (MIDI)A pair of controller messages that pick a sound bank before a Program Change picks the sound within it.
- Bank switchingSwapping which slice of an oversized ROM shows through the CPU's small address window — how 8-bit games broke their own…
- BankgirotThe Swedish banks' shared clearing house, which since 1959 has made sure a payment from one bank actually reaches another.
- Banner grabbingConnect to a port and read what the server voluntarily discloses — version, OS, software.
- Banner pageThe cover sheet with the job name and user that a shared printer prints first, so the stacks can be told apart in the output…
- Banyan SystemsThe networking company that had a global directory service almost a decade ahead of its rivals, and lost anyway.
- Banyan VINESA network operating system whose global directory service was years ahead of everyone else's.
- Bar Mitzvah attackA 2015 attack on RC4 in TLS that exploited a weakness then thirteen years old — hence the name.
- Barbara LiskovThe computer scientist whose work on abstract data types underlies essentially everything we now call object orientation.
- Barbara SimonsThe IBM researcher and former ACM president who spent the second half of her career getting American voting machines…
- Barcode scannerAn optical reader that decodes a barcode from the pattern of light and dark it reflects.
- Barcode symbologyThe set of rules deciding how data is turned into bars and spaces in a given kind of barcode.
- Barcode verifierAn instrument that grades a printed barcode — not whether it reads here, but whether it will read everywhere.
- Barcode wandThe pen-shaped reader you dragged by hand across a printed barcode — the simplest of the early scanners.
- Barium ferriteThe barium-ferrite (BaFe) magnetic powder that today's data tape is coated with — chemically stable and built to last for…
- BARKSweden's first computer clacked out its answers on a few thousand telephone relays, two years after the state decided the…
- BarmanPostgreSQL backup built around a central catalogue server managing many database servers, as opposed to tools that run on…
- Barnaby JackNew Zealand hacker who made cash machines spew banknotes on stage, then turned his attention to medical devices.
- Barracuda NetworksThe spam-filter box that grew into a whole shelf of security appliances for email and the web.
- Barrett BrownAmerican journalist who mapped the surveillance-contractor industry through leaked email and went to prison over what…
- Barry VercoeNew Zealand composer and MIT researcher who wrote Csound, the longest-lived descendant of MUSIC-N.
- Bart PreneelBelgian cryptographer at KU Leuven whose name is on RIPEMD-160, Miyaguchi–Preneel and about half of Europe's cryptography…
- Bartle taxonomyRichard Bartle's split of MUD players into four types — achievers, explorers, socialisers and killers — which game designers…
- Barton GellmanThe third journalist to receive Edward Snowden's documents, and the one who brought them to The Washington Post.
- Barton MillerThe Wisconsin professor who named fuzzing after a thunderstorm crashed his Unix tools.
- Barycentric coordinatesThree weights that sum to one, expressing a point as a blend of a triangle's three vertices.
- BASEThe opposite of ACID — Basically Available, Soft state, Eventual consistency.
- Base stationThe radio equipment forming a cell in the mobile network — what the phone actually talks to.
- Base64Encoding for representing binary data as ASCII text. 6-bit chunks → 64-character alphabet (A–Z a–z 0–9 + /). File grows…
- BasecampThe project tool whose development happened to give the world Ruby on Rails — and whose founders have made a sport of…
- Bash (Bourne Again SHell)The dominant Linux shell — the language for terminal scripts and CI pipelines.
- Basho TechnologiesThe company behind Riak, a distributed key-value database built straight on Amazon's Dynamo paper — the whole point was…
- BASICA language written for students with no mathematics background that ended up in ROM on every home computer.
- Bass managementThe feature in a receiver or audio processor that strips the bass from every channel and sends it to the subwoofer instead.
- Bass trapAn absorber built to tame the low frequencies that thin acoustic panels can't touch.
- Bastion host (Jump host)Hardened server that is the only way into an internal environment — you SSH there first, then onward.
- Batch fileA text file of commands that DOS and Windows run in order — the .bat file, the scripting language nobody chose but everybody…
- Batch normalizationNormalizing each feature across all samples in the minibatch. Presented by Ioffe and Szegedy in 2015 and one of the single…
- Batch processingProcessing large volumes of data in bounded runs rather than event by event. The oldest data processing model there is…
- Batch sizeHow many training examples the model looks at before updating weights.
- Batman Forever (demo)The 2011 Amstrad CPC demo that proved a machine many had written off still had unused tricks left after nearly three decades.
- BatMUDA Finnish MUD from 1990 that is still running — one of the oldest text-based online worlds never to have shut down.
- BatteryPower source in portable devices — capacity given in mAh or Wh.
- Battery-backed cacheRAM cache with battery or supercapacitor + flash that retains data on power loss. Standard on enterprise RAID controllers…
- Battle royaleA hundred players, a shrinking map, one survivor — the genre that went from mod to the industry's most copied format in…
- Baudot codeThe five-bit code of 1874 turned letters into fixed bit patterns ninety years before ASCII, and gave the baud its name.
- Baumgarte stabilizationA trick in constraint solvers that feeds a fraction of the positional error back as a velocity bias, so the same solver that…
- Bay NetworksFour years of trying to build a counterweight to Cisco by bolting a hub maker onto a router maker.
- Bayer matrixThe recursively defined threshold matrix that ordered dithering compares against, built so the thresholds are spread out as…
- BazelGoogle's hermetic build system — open-source version of internal "Blaze" (2015). Reproducible builds, fine-grained…
- Bazeries cylinderA cylinder cipher with about twenty rotating disks, described by the French cryptanalyst Étienne Bazeries.
- BB84The first quantum key distribution protocol, and still the most used — published in 1984 by Charles Bennett and Gilles…
- BBC MicroThe school computer the BBC commissioned to teach Britain to program — whose successor became the processor in your phone.
- BBN (Bolt Beranek and Newman)The acoustics consultancy from Cambridge, Massachusetts, that built ARPANET's switches and, along the way, gave email its @.
- BBR (Bottleneck Bandwidth and RTT)Google's congestion control algorithm, which measures what the link can actually carry instead of waiting for packet loss to…
- BBS (Bulletin Board System)Dial-up server running on a home computer (usually in the sysop's basement) — reachable via modem, for messaging, file…
- BBS: The DocumentaryJason Scott's 2005 documentary series about bulletin board systems, told by the people who ran them.
- BBStroAn intro coded to advertise a bulletin board — the cracktro's cousin, aimed at dial-up systems.
- BCPLThe Cambridge language from 1967 that became B that became C — and gave the world its first "hello, world".
- bcryptPassword hashing function. Niels Provos + David Mazières, 1999. Adaptive via "work factor" (cost) — increase as CPUs get…
- bcrypt_pbkdfThe key derivation function that protects passphrase-encrypted private keys in OpenSSH's own key format.
- BDD (Behavior-Driven Development)Testing style describing behaviors in natural language: Given-When-Then. Dan North, 2003. Riff on "outside-in TDD" — start…
- BDFAdobe's plain-text format for bitmap fonts, which became the way X11 distributed its pixel fonts.
- Be Inc.The company behind BeOS, which very nearly became Apple's next operating system and became a cult classic instead.
- BEA SystemsThe middleware company whose WebLogic was the application server enterprise Java actually ran on around the turn of the…
- Beacon APIA call that hands a small amount of data to the browser with a promise that it will be sent, even if the page closes at that…
- BeaconingWhen a compromised machine regularly "calls home" to its command-and-control server to fetch instructions. The predictable…
- Beale ciphersThree numeric ciphers said to lead to buried treasure in Virginia; one is solved, two aren't, and the treasure has never…
- Beam searchDecoding strategy that keeps several "candidate sequences" in parallel — picks the one with the highest total probability.
- Beam search (LLM)A decoding strategy that keeps several candidate sequences ("beams") alive in parallel and extends them step by step, to…
- BeamformingShaping and aiming a radio signal toward a specific receiver instead of radiating evenly in all directions. By fine-tuning…
- BEAR and LIONTwo block ciphers with arbitrarily large blocks, assembled from a hash function and a stream cipher in three Feistel rounds.
- Bearer tokenToken where "whoever holds it can use it" — no key exchange required. The cash-in-a-wallet model. RFC 6750.
- BEAST attackAn attack on TLS 1.0 where a predictable initialization vector in CBC mode leaked plaintext, including cookies, one byte at…
- Beat trackingTeaching a computer to tap its foot — estimating the tempo and placing every beat in a recording.
- BeatmatchingThe DJ craft of locking two tracks to exactly the same tempo and phase so the transition goes unnoticed.
- Beaufort cipherA Vigenère variant that computes key minus plaintext, so the same operation both encrypts and decrypts.
- BeboSocial network from 2005 that dominated Britain and Ireland, and which AOL bought for $850 million just before the whole…
- BeckhoffGerman automation firm that turned the PC into a PLC and invented the EtherCAT fieldbus.
- Bedroom coderA teenager writing commercial games on a home computer in their bedroom — the 1980s British games industry in two words.
- BeeGFSGerman parallel filesystem for HPC — designed for easier deployment compared to Lustre. Open source, commercial support via…
- BEEPThe IETF's attempt at a general framework for application protocols — so nobody would have to reinvent handshakes and…
- Beeper musicMusic squeezed out of the ZX Spectrum's single beeper — a 1-bit output that can really only switch on and off.
- BefungeAn esoteric programming language where the code is a grid and execution moves in all four directions.
- Behavior treeA hierarchical model for game AI where decisions are built from sequence and selector nodes, ticked each frame, returning…
- BelkinA Californian accessory brand that went from printer cables in a garage to owning Linksys.
- Bell (X11)The X protocol's only sound feature: a request asking the server to beep, at a volume given in percent.
- Bell LabsThe most productive institution in the history of industrial research — the transistor, information theory, Unix and C all…
- Bell Labs Model VThe largest relay computer ever built — slow on purpose, because Bell Labs preferred a right answer tomorrow to a wrong one…
- Bell stateThe four maximally entangled states of two qubits — quantum mechanics' simplest demonstration that the whole cannot be…
- Bellcore attackA single faulty RSA signature computed with CRT can be enough for an attacker to recover the primes behind the key.
- Bellman-FordShortest-path algorithm for graphs with negative edge weights — Dijkstra's stronger cousin when Dijkstra's basic assumption…
- BEM (Block Element Modifier)Naming convention for CSS classes: .card__title--large.
- Ben AdidaAmerican cryptographer who built the Helios web voting system and then turned to making ordinary elections auditable.
- Ben DaglishBritish composer whose C64 music for The Last Ninja and Gauntlet, among others, is some of the most-played on the SID chip.
- Ben HawkesSecurity researcher on Google Project Zero's original roster, who went on to lead the team during the years its 90-day rule…
- Ben LaurieBritish security engineer who gave the web server encryption and the certificate system a public audit log.
- BenchmarkStandardized performance test. Compares CPU/GPU/system/software over time or between implementations. More politics than…
- Benjamin DelpyFrench programmer who wrote Mimikatz as a side project and in doing so changed how Windows networks get defended.
- Benjamin JunThe third name on the differential power analysis paper — the one that showed a smart card's power draw is a leak.
- Benne de WegerDutch mathematician who helped show that an MD5 collision was not a curiosity but a way to become a certificate authority.
- Benny PinkasIsraeli cryptographer who helped turn secure multiparty computation into something you can actually run — and who showed how…
- Bent functionA Boolean function that sits as far from every linear function as it is mathematically possible to get.
- Bent normalsA per-pixel direction pointing toward where the surrounding geometry is least occluded, used to make ambient lighting…
- BeOSWritten from scratch for multimedia in the 1990s, with no backward compatibility to carry — and very nearly Apple's next…
- BeRealFrench app that sends a daily random-time notification ("Time to BeReal!") — all users have 2 minutes to take a photo with…
- Berkeley MailKurt Shoens' line-oriented mail program from 1978, which became BSD's Mail and survives as the POSIX command mailx.
- BerkNetBerkeley's home-grown network of serial cables between campus machines, written by a grad student who later ran Google.
- Berlekamp–Massey algorithmFinds the shortest LFSR that generates a given bit sequence, needing only 2L output bits for a register of length L.
- Bernd FixGerman hacker credited with the first documented removal of a computer virus, in 1987.
- Bernoulli BoxIomega's 1982 cartridge storage where a flexible disk was pulled toward the head by the Bernoulli effect — crash-resistant…
- BERTGoogle's transformer model from 2018 — groundbreaking for understanding (encoder-only, reads in both directions).
- Bert den BoerDutch cryptographer who exposed the first crack in MD5 in 1993 — eleven years before anyone produced a real collision.
- BerylThe Compiz fork that, for six months in 2006–2007, was the wobbliest Linux desktop around, before the two merged again.
- BesiA Dutch packaging company that bet everything on hybrid bonding — the technique meant to hold the chiplet era together.
- Best-of-NGenerate N answers and pick one. The simplest form of buying quality with compute at inference time rather than at training…
- Bethesda SoftworksThe Maryland publisher behind The Elder Scrolls and Fallout, now part of Microsoft.
- Betty HolbertonENIAC programmer who went on to write the first sort/merge generator and to sit on the standards committees for both COBOL…
- Bev HarrisAmerican writer who in 2003 found Diebold's election software sitting on an open server, then spent years showing what could…
- BevyA data-driven game engine in Rust, built entirely around an ECS architecture — young, fast-growing and open.
- Beyond-birthday-bound securityModes of operation and MACs whose security proofs hold well past 2n/2 blocks, beyond the usual collision limit.
- BeyondTrustAn American security vendor that sells tools for restricting and logging admin privileges — and whose own remote-support…
- Bézier curveA smooth curve defined by a handful of control points, where the curve passes through its endpoints and is pulled toward the…
- BF16 (bfloat16)16-bit floating-point format with 8 exponent bits (the same range as FP32) but only 7 mantissa bits — the sweet spot for ML…
- BFD (Bidirectional Forwarding Detection)A minimal heartbeat protocol that detects a dead link in milliseconds instead of seconds. Specified in RFC 5880 (2010) and…
- bfloat16 (Brain Float 16)A 16-bit floating point format devised by Google Brain for TPUs. It simply takes IEEE 754's 32-bit format and chops off the…
- BFS (Breadth-First Search)Graph traversal that explores level by level. Uses a queue instead of a stack. Finds shortest paths in unweighted graphs.
- BFS (Breadth-First Search)Graph traversal that visits every node at one depth before moving to the next. Implemented with a FIFO queue.
- BGA (Ball Grid Array)Chip package with solder balls on the underside instead of pins around the edge — more contacts in less area.
- BGA (Ball Grid Array)A chip package where the connections are a grid of small solder balls on the underside, melted directly onto the circuit…
- BGE (BAAI General Embedding)Open-source embedding family from BAAI (Beijing Academy of AI) — tops MTEB leaderboards with models from 33 MB to 7 B…
- BGE embeddings (BAAI General Embedding)Chinese Beijing Academy of AI's open-weight embedding models — top of the MTEB benchmark, free to run yourself.
- BGP (Border Gateway Protocol)The protocol routers on the internet use to tell each other "I can reach these IP prefixes, route through me".
- BGP AS-pathThe list of autonomous systems (AS) a BGP route has passed through on its way to you. It serves two roles: loop prevention…
- BGP communitiesLabels you attach to BGP routes to group them and signal policy — like tags that routes carry with them between routers and…
- BGP confederationAn alternative way to solve iBGP's scaling problem: split a large autonomous system into several smaller "sub-ASes" that run…
- BGP FlowSpecA BGP extension (RFC 5575) for distributing flow filter rules through the network — "drop all traffic to IP X on port Y"…
- BGP hijackAn ASN announces an IP prefix it doesn't own — by mistake or on purpose — and traffic gets routed the wrong way.
- BGP hijackingWhen an autonomous system (deliberately or by accident) advertises IP prefixes it doesn't own in BGP, thereby hijacking and…
- BGP local-prefLocal Preference — the BGP attribute that controls which outbound path an autonomous system prefers when there are several…
- BGP MEDMulti-Exit Discriminator — a BGP attribute that suggests to a neighboring AS which of several entry points it should use to…
- BGP peeringThe establishment of a BGP session between two routers (peers/neighbors) so they can exchange routes. Unlike IGPs, BGP…
- BGP route flap dampingA BGP mechanism that "penalizes" unstable routes that repeatedly appear and disappear (flap), by temporarily suppressing…
- BGP route reflectorA solution to iBGP's scaling problem: instead of every internal BGP router needing a session with every other (a full mesh)…
- Bi-encoderNeural network architecture that encodes query and document independently to vectors, then compares with…
- BiasWhen an ML model systematically favours or discriminates based on the data it was trained on.
- BICThe eight- or eleven-character address that identifies a bank on the international payment network, better known as the…
- Biclique attackA 2011 attack that gave the first result against full AES faster than brute force, if only by a small margin.
- Bidirectional printingLaying down characters on the head's return sweep too, instead of treating the trip back as dead travel.
- biffThe Unix command that announced new mail in your terminal, named after a dog that barked at the postman.
- Bifid cipherSplits each letter into row and column coordinates, shuffles the coordinates and reassembles them into new letters.
- Big 8The eight Usenet hierarchies where a new group needed a public debate and a vote — the opposite of alt.*.
- Big Drives (48-bit LBA)Maxtor's name for 48-bit LBA, which in 2002 blew past the 137 GB ceiling on ATA disks.
- Big Dummy's Guide to the InternetThe EFF's free internet manual from 1993, written for people who dialled into a BBS and suddenly found the whole world…
- Big Picture ModeSteam's full-screen mode for TVs and controllers — the ten-foot interface that later became the basis for the Steam Deck.
- Big-endian vs Little-endianHow multi-byte numbers are stored in memory — most significant byte first (big) or last (little).
- Big-O notationA way of describing how an algorithm scales with input size: O(1), O(n), O(n log n), O(n²).
- BIG-REQUESTSThe X11 extension that raised the ceiling on a single request from 256 kilobytes to 16 megabytes, through a trick with the…
- big.LITTLEARM's architecture that combines large, powerful cores ("big") with small, energy-efficient cores ("LITTLE") on the same…
- BigQueryGoogle's serverless data warehouse — run analytical SQL on petabyte-scale data without managing clusters. Based on the…
- BigramA pair of consecutive letters whose frequency tells a cryptanalyst far more than single letters do.
- BigtableGoogle's distributed wide-column database, and the ancestor of half the NoSQL world.
- Biham–Kocher attackA known-plaintext attack that breaks the legacy password encryption of ZIP archives with about a dozen known bytes.
- BildschirmtextWest Germany's videotex network, best remembered for the Chaos Computer Club draining a savings bank through it in 1984.
- Bilinear filteringSmooths magnified textures by taking a weighted average of the four nearest texels.
- Bill CheswickThe Bell Labs researcher who co-wrote the first serious book on firewalls and kept an intruder busy for months just to watch…
- Bill GatesFounded Microsoft with Paul Allen in 1975 and negotiated the deal that made software the industry's profit centre.
- Bill LandrethThe teenage hacker "The Cracker", arrested in 1983, who two years later published a book on computer security — through…
- Bill MarczakCitizen Lab researcher who caught NSO Group's Pegasus spyware inside a text message link in 2016.
- Bill TutteThe chemist who worked out the internal wiring of a German cipher machine without ever seeing one, or even a photograph of…
- BillboardingDrawing a flat quad that always turns to face the camera, so a 2D image passes for a 3D object.
- Billy HoffmanThe Georgia Tech student who was barred by court order from explaining how to fool campus card readers, and who later became…
- Billy RiosAmerican security researcher whose infusion pump findings led the FDA, for the first time, to warn hospitals off a product…
- BINACThe machine with two processors running the same program and comparing answers after every instruction — 1949, and mostly…
- BinanceThe world's largest crypto exchange by trading volume, and for years proud of having no headquarters at all.
- Binary number systemNumber system with just 0 and 1 — the language computers actually count in.
- Binary searchFind an element in a sorted sequence in O(log n) time. Halve the search space at each step — check the middle, go left or…
- Binary treeHierarchical data structure where every node has at most two children (left and right). A building block for many other…
- Binary-coded decimal (BCD)Encoding each digit on its own in four bits instead of turning the whole number into binary — decimal arithmetic that…
- Binaural recordingRecording with two microphones in the ears of an artificial head, so a listener on headphones hears the room as if sitting…
- bind (monad)Monad operation: chain a function that returns a monadic value. Haskell: >>=. JavaScript: Promise.then (Promise is a monad)…
- Bind poseThe reference stance — often a T- or A-pose — a model holds at the moment it is bound to its skeleton, and against which all…
- Binding (programming)Association between a name and a value. Variable binding: let x = 5. Data binding: ties a UI element to underlying data…
- Bindless texturesA GPU model where shaders look up textures through handles in memory, instead of every draw binding them to fixed slots.
- BinHexThe Mac world's answer to uuencode: an encoding that turned files into text while keeping both the data and resource forks…
- Bink VideoThe video codec behind nearly every game intro and cutscene for two decades, because it was built for game engines rather…
- BinkleyTermA FidoNet mailer that picked up the phone before the BBS did and handled the nightly mail exchange with other nodes.
- binkpA protocol for moving FidoNet mail over TCP/IP instead of phone lines.
- Binlog (binary log)MySQL's binary log that records all changes to data (and schema) as a sequence of events. The basis for replication…
- BinningSorting finished chips by what they can actually do. The reason a product family with six different models is often built…
- BioinformaticsComputer science applied to biological sequences — string matching where the strings happen to be DNA.
- BiomeA formatter and linter for web projects, written in Rust. A fork of Rome Tools taken over by the community in 2023 when the…
- Biometric authenticationUnlocking with a fingerprint or a face — convenient, but technically a shortcut to a key rather than a password in itself.
- bionet.*The Usenet hierarchy for biologists, started in the late 1980s and mirrored to mailing lists so that labs without Usenet…
- BIOS (Basic Input/Output System)The tiny software that starts your computer before the OS takes over — since ~2010 mostly replaced by UEFI.
- BiostarSecond-tier Taiwanese motherboard maker, best known for budget boards and crypto-mining planks.
- BIP-32The Bitcoin proposal describing how one secret seed can deterministically generate an entire tree of child keys.
- Biquad filterThe building block of digital audio filtering: a recursive second-order filter with five coefficients that can be a lowpass…
- Biquinary codeA digit encoding borrowed from the abacus's split into fives and ones, so that a failed relay would announce itself…
- Birthday attackCollisions show up after the square root of the possibilities, not the possibilities — which is why a 256-bit hash is only…
- Birthday boundHow much data a block cipher can safely process under one key before block collisions start leaking information — roughly…
- BitThe smallest unit of information — one choice between two alternatives, zero or one.
- Bit cellThe fixed clock window on the medium that holds exactly one bit; the encoding decides whether and where a flux transition…
- Bit depthThe number of bits used for each audio sample — and therefore how far down the noise floor sits.
- Bit-flipping attackAn attacker changes bits in the ciphertext to predictably change the plaintext, without ever reading it.
- Bit-patterned mediaA proposed hard-drive medium where every bit gets its own lithographically stamped magnetic island instead of a scatter of…
- Bit-perfect playbackGetting the samples in a file to the DAC exactly as stored — without the operating system's mixer resampling, scaling or…
- bit.*The Usenet hierarchy that mirrored BITNET mailing lists, letting two academic networks read the same discussions.
- BitBLTThe operation that copies a rectangular block of pixels from one place to another and combines it with whatever is already…
- BitbucketAtlassian's code-hosting service — once Mercurial's foremost home, now a Git hub woven tightly into Jira.
- BitchXThe 1990s' most attitude-laden Unix IRC client: ircII with a script pack built in, ANSI colours, and quit messages that were…
- BitcoinFirst decentralized cryptocurrency. Anonymous creator "Satoshi Nakamoto", white paper October 2008, genesis block January…
- BitcrusherAn effect that deliberately makes digital audio worse, throwing away the bits and samples engineers once fought hard to get.
- BitdefenderRomanian antivirus company whose engine ships inside more products than the ones carrying its name.
- BitemporalA data model that tracks two time dimensions at once: "valid time" (when a fact was true in the real world) and "transaction…
- BITFTPPrinceton's service that let BITNET users fetch files from Internet FTP archives by sending a message.
- BitlBeeAn IRC server that pretends to be a chat network but is really a gateway to other services. It lets an ordinary IRC client…
- BitLockerMicrosoft's disk encryption in Windows — full-volume encryption with the key sealed inside the TPM chip.
- BitmainThe Chinese chip designer whose Antminer boxes long decided who made money mining bitcoin.
- BitmapPixel-based image (raster image). Each pixel is stored explicitly. The BMP file format (Microsoft, 1980s) is the default…
- Bitmap fontA font stored as pre-drawn pixel cells rather than mathematical outlines — fast and pixel-perfect at its size, mushy the…
- Bitmap heap scanThe PostgreSQL plan node used when an index matches too many rows for a plain index scan but too few to justify reading the…
- Bitmap indexAn index that stores a bit-vector per distinct value. Good for low-cardinality columns (gender, status, category). AND/OR…
- BITNETThe academic network built on IBM mainframes, which gave universities email and mailing lists before most of them could…
- BitplaneA way of storing an image as several separate one-bit layers, where the layers together pick out each pixel's colour.
- BitrateHow many bits per second an audio or video stream consumes — the single most important dial for quality against file size.
- bitsandbytesThe library that made running large models on a single consumer graphics card normal. Written by Tim Dettmers and known for…
- BitslicingAn implementation technique that treats a CPU word as dozens of parallel one-bit processors and rewrites S-boxes as pure…
- BitTorrentP2P protocol for distributed file sharing. Bram Cohen, 2001. Files shared via a "swarm" of peers instead of a central…
- BitwardenPassword manager with open-source clients and server, which makes it the one you can run entirely on your own hardware.
- Bitwig StudioA Berlin DAW built by former Ableton people, with modulation as its organising principle and Linux as a first-class platform.
- Bitwise operatorsOperators that work bit by bit on integers: AND &, OR |, XOR ^, NOT ~, shift << >>.
- Biuro SzyfrówPoland's Cipher Bureau, which hired mathematicians instead of linguists and so broke Enigma before anyone else.
- BIXBYTE magazine's own dial-up conferencing service, where readers, writers and developers argued about technology in depth.
- BixbySamsung's voice assistant, launched in 2017 and built on technology from Viv Labs — founded by the same people who once…
- biz.*The Usenet hierarchy where commercial posts were explicitly allowed — an attempt to give advertising its own shelf so it…
- Bjarne StroustrupThe Dane who put classes on top of C and thereby gave the world a language that, forty years on, still runs most things that…
- Bjørn LynneNorwegian composer who went from the scene handle Dr. Awesome on the Amiga to the soundtrack of Worms.
- Black Duck SoftwareThe company that turned "what open source is actually in our product, and under which licences?" into a business.
- BlackBerryThe Canadian phone with a physical keyboard that owned corporate life for a decade, then vanished in four years.
- Blackboard (AI)A shared memory that different AI components read from and write to in order to coordinate, instead of calling each other…
- BlackboxA lean, good-looking C++ window manager from 1997 that became the ancestor of Fluxbox and Openbox.
- Blackmagic DesignAn Australian manufacturer that kept cutting the price of professional video gear until competitors had to rethink their…
- BlackwellNvidia's 2024-2025 datacenter GPU generation. B200: 2 chiplets + 192 GB HBM3e. ~2.5x inference vs H100. RTX 50 series (2025)…
- Blaise de VigenèreFrench diplomat whose name ended up on a cipher he did not invent.
- Blaise PascalThe nineteen-year-old who built a calculating machine to spare his father the arithmetic of tax collection, then spent the…
- BlaizeEdge-AI company whose "graph streaming" architecture flows the whole neural net through the chip instead of constantly going…
- BLAKE2A fast hash function from 2012, built as a successor to SHA-3 finalist BLAKE.
- BLAKE3Cryptographic hash function from 2020 by Jack O'Connor, Jean-Philippe Aumasson, Samuel Neves and Zooko Wilcox-O'Hearn. The…
- Blameless post-mortemIncident review where focus is on the system and the processes, not on who "pushed the wrong button".
- BlazorMicrosoft's framework for building web UI with C# instead of JavaScript. Steve Sanderson, 2018. Two modes: Server…
- BLE-MIDIMIDI over Bluetooth Low Energy: wireless keyboards and controllers that talk to a phone or laptop without a cable, and…
- Bleichenbacher attackDaniel Bleichenbacher's 1998 attack that decrypted RSA ciphertexts by asking a server whether the padding was valid.
- Blend spaceContinuously mixes several animation clips along one or two parameter axes — such as speed or direction — rather than…
- Blend treeA node graph that smoothly mixes several animation clips by weight — walking easing into running as speed rises — instead of…
- BlenderOpen-source 3D suite — modelling, sculpting, animation, rendering, video editing. Genuinely competes with Maya and 3ds Max…
- Bletchley ParkA Victorian country house in Buckinghamshire where close to ten thousand people secretly read German military traffic — and…
- BlinkChromium's rendering engine. Forked from WebKit in April 2013 by Google. Powers Chrome, Edge, Brave, Opera, Vivaldi, Arc…
- Blinn-PhongA reflection model that approximates specular highlights with a halfway vector — a cheaper variant of Phong's model.
- Blip FestivalThe New York chiptune festival that moved music made on Game Boys and old home computers out of forum threads and into…
- BlitBell Labs' 1982 graphical terminal, offering multiple windows onto one Unix host and running programs downloaded into the…
- BlitterThe Amiga's graphics engine that moves blocks of screen memory with logic — behind every smoothly animated BOB and…
- BlittingCopying a rectangular block of pixels from one buffer to another in a single fast operation — the workhorse of 2D graphics.
- Blitz BASICCompiled BASIC for the Amiga, fast enough for real games — Worms was written in it.
- Blizzard EntertainmentThe studio behind Warcraft, StarCraft and Diablo, which turned online games into a service long before "live service" was a…
- BloatDead space left behind in tables and indexes by MVCC. An UPDATE actually writes a new row version and marks the old one dead…
- BLOBBinary Large Object — a lump of binary data the database stores without pretending to understand it.
- Bloch sphereThe globe drawn to show what state a single qubit is in — north pole is zero, south pole is one, everything between is…
- Block (Square)The payments company that started as a white card reader in a phone's headphone jack and ended up as a bitcoin venture with…
- Block cipherEncrypts exactly one chunk at a time — and is therefore useless without a mode of operation telling it what to do with chunk…
- Block compressionLossy, fixed-ratio texture compression in which 4×4 blocks of texels are packed into fixed-size blocks that the graphics…
- Block deviceA device read and written in fixed-size blocks with random access — disks, SSDs, USB sticks.
- Block sizeHow many bits a block cipher encrypts at once, and one of the quiet factors in how long a key actually lasts.
- Block vs. muteTwo different ways to be rid of someone: blocking (they can no longer see or contact you — visible and mutual) or muting…
- BlockchainDistributed, append-only database where each block is cryptographically linked to the previous one. Changes require…
- BlocketSweden's dominant second-hand marketplace — started in Skåne in 1996, bought by Schibsted in 2003.
- Blocklist (Bluesky)Bluesky feature: shared blocklists that users can subscribe to. Maintainer curates list of problem accounts; subscribers…
- BlocktronicsAn international ANSI art collective keeping the textmode scene alive long after the BBS era.
- BloodHoundThe tool that draws Active Directory as a graph and lets you ask for the shortest path from any account to Domain Admin.
- BloomA post-processing effect that lets very bright surfaces bleed out as a glow into surrounding pixels, mimicking light…
- Bloom filterProbabilistic data structure for "is the element in the set?" — answers "maybe" or "definitely not". No false negatives…
- Bloom filter indexAn index based on a Bloom filter — a probabilistic data structure that can quickly say "the row definitely does not match"…
- BlowfishSchneier's free DES alternative from 1993 — whose slow key schedule turned out to be its most useful property.
- BLT (Byte Latent Transformer)Meta's December 2024 architecture that drops the tokenizer entirely and instead groups raw bytes into dynamically sized…
- Blu-ray DiscOptical format that succeeded DVD. Sony-led, launched 2003. Uses blue-violet laser (405 nm) for higher storage density. Won…
- Blue boxThe tone generator that mimicked the phone network's own control signals to take command of long-distance lines — Wozniak's…
- Blue CoatA maker of proxy appliances that began as a web cache and ended up as a censorship tool in the wrong hands.
- Blue noiseNoise whose energy sits in the high frequencies, with no low-frequency clumps — the points spread evenly but irregularly…
- Blue PillJoanna Rutkowska's 2006 proof of concept that slid a running operating system into a virtual machine without the OS noticing.
- Blue WavePopular offline reader from the BBS era that bundled up messages so you could read and reply without staying connected.
- Blue-green deploymentA deployment strategy with two identical production environments — "blue" (current) and "green" (the new version). You…
- BluecurveRed Hat's 2002 theme that dressed GNOME and KDE in the same blue curves so nobody could tell which one they were running…
- BluehostThe Provo, Utah web host that sat at the top of WordPress's own list of recommended hosts for the better part of two decades.
- BlueskyTwitter-style microblog built on the AT Protocol — originally sponsored by Jack Dorsey, launched publicly in February 2024.
- Bluesky Custom FeedBluesky feature: users build their own feed algorithms that others can subscribe to. Sets Bluesky apart from…
- Bluesky domain handleBluesky feature: use your own domain as handle instead of @user.bsky.social. Set a DNS TXT record + claim the domain →…
- Bluesky firehoseA real-time stream of all public events in the Bluesky network — every post, like, follow, and repost as they happen. The…
- BluetoothShort-range wireless communication — headphones, mice, IoT devices.
- BM25 (Best Match 25)Classic lexical search ranking algorithm — TF-IDF with saturation and length normalisation. The standard in Elasticsearch…
- BMCBaseboard Management Controller — a separate microcontroller on the server motherboard that runs regardless of whether the…
- BMC SoftwareThe Houston company selling the unglamorous tools that keep mainframes and IT departments running — and buying up most of…
- BMP (BGP Monitoring Protocol)A protocol where a router pushes its BGP tables and every update to an analysis station. Solves the problem that you…
- Board operatorThe administrator and operator of a BBS (Bulletin Board System) — usually an enthusiast running the system from home on…
- Boaz BarakLead author of the paper proving that perfect code obfuscation is impossible, which in the same breath defined the weaker…
- BOB (blitter object)Blitter OBject — a graphic object blitted into the playfield itself, as opposed to the hardware sprite the video chip…
- Bob KahnThe other half of TCP/IP — and the person who built ARPANET's hardware side before the protocols were even on the agenda.
- Bob ScheiflerThe principal architect of the X Window System, who wrote the protocol in 1984 and then ran the X Consortium for eight years.
- Bob ThomasBBN programmer who in 1971 wrote Creeper, the first program to move itself between computers on a network.
- Bobby Ray InmanThe admiral who ran the NSA from 1977 to 1981 and was the first NSA director to try, in public, to rein in academic…
- Bodo MöllerGerman cryptographer and early OpenSSL developer who co-discovered POODLE in 2014 and then wrote the fix for downgrade…
- BOFHThe Bastard Operator From Hell — a sysadmin who loathes his users and makes sure they know it, in a serial that started on…
- BoidsCraig Reynolds's 1986 flocking simulation in which each individual follows three local rules and flocking emerges on its own.
- BoilerplateRepetitive standard code that has to be written but adds nothing new — getters/setters, error handling patterns, project…
- Boing BallThe bouncing red-and-white checkered ball that showed off the Amiga prototype at CES in January 1984 and became the…
- BokehThe aesthetic shape of out-of-focus highlights — the glowing discs a lens's aperture leaves beyond the focal plane.
- Bomba (Polish machine)Polish machine from 1938 that searched for Enigma keys by brute force, and the forerunner of Turing's bombe.
- Bomba kryptologicznaThe Polish machine that was reading Enigma three years before the war, by exploiting the fact that the Germans sent the…
- BombeThe Bletchley Park machine that never broke Enigma so much as eliminated everything impossible, until too little was left to…
- Bonding (Linux)Linux feature: bundle multiple NICs into one logical interface. Modes: active-backup (failover), balance-rr (round-robin)…
- Bone weightA value per vertex and bone that decides how much that bone drags the vertex along when the skeleton moves — the weights…
- BonfireA modular framework for building federated social networks, written in Elixir. Unlike Mastodon (a finished product), Bonfire…
- BonoboGNOME's component model from 1999, built on CORBA, meant to let a spreadsheet be embedded in a text document and instead…
- BonzomaticA fullscreen shader editor that overlays the code on its own output, built for live coding on stage.
- Book cipherEach word or letter is replaced by a pointer — page, line, word — into a book that both sender and recipient own.
- Booking.comThe world's biggest OTA (Online Travel Agency) — the hotel booking service that takes 15–25 % commission from every hotel…
- BooleanA type with exactly two values: true or false. Named after the mathematician George Boole.
- Boomerang attackA differential attack that chains two shorter differentials, which is where the name comes from.
- Boomerang connectivity table (BCT)A table over an S-box giving the exact probability that a boomerang makes it through the S-box where its two halves meet.
- BoomiA cloud integration platform that wires apps and data together through drag-and-drop instead of hand-written glue code.
- Boost (Mastodon)Mastodon's equivalent of a retweet — forward someone else's post to your followers unchanged. Formerly called "reblog"…
- Boot sectorThe first 512 bytes of a disk: just enough code to fetch the rest of the operating system.
- Bootblock introA tiny intro squeezed into the Amiga's 1024-byte boot sector, often a cracktro or a coded calling card.
- BootloaderThe program BIOS/UEFI runs which in turn loads the OS kernel.
- BootstrapThe most-used CSS framework — ready-made components (buttons, grid, modals), responsive out of the box.
- Booze DesignC64 demo group that proved a twenty-five-year-old breadbin still had unused raster lines left in it.
- BorgBackupA deduplicating backup tool, forked from Attic in 2015. Written in Python with performance-critical parts in C. The classic…
- Boris Floricic (Tron)German hacker from the CCC circle, known as Tron, whose death in Berlin in 1998 has never stopped being argued over.
- Boris HagelinThe Swede who became the first person to get rich from encryption — and whose company turned out, much later, to be selling…
- BorlandThe rebels of developer tools: sold a fast Pascal compiler for $49.95 when rivals charged hundreds, and taught a generation…
- Borrow checkerThe Rust compiler subsystem that validates ownership + lifetime rules. Guarantees memory safety + thread safety without a…
- Bosch RexrothBosch-owned specialist in drive and control technology — hydraulics, servos and motion control for heavy industry.
- BOSHThe tool that deploys and manages the lifecycle of entire distributed systems — built for Cloud Foundry, long before…
- BotA program acting as a user — answering, moderating, posting or spamming, depending on who wrote it.
- Bot protocolA platform's API for programmable accounts — bots. Telegram Bot API (polling or webhook), Discord Interactions (slash…
- BotnetA network of compromised devices under an attacker's control — "zombies".
- Bounded ContextDDD concept: a bounded slice of the domain where words and models have a specific, consistent meaning.
- Bounding boxThe smallest rectangle that fully encloses an object — the basis for layout, hit areas and collision tests.
- Bounding sphereThe simplest bounding volume: a sphere wrapped around an object, so the collision test is nothing more than comparing…
- Bounding volumeA simple shape that fully encloses a complex object, letting a cheap test reject it before the expensive one ever runs.
- Bounding volume hierarchy (BVH)A tree of bounding volumes in which every node encloses its children, so whole branches can be dismissed with one test.
- BowerPackage manager for frontend libraries. Twitter, 2012. Was standard for web 2012–2016 before npm ate the ecosystem…
- BowmanThe window manager that dressed fvwm in NeXTSTEP clothes in 1996 and, after a rename, became AfterStep.
- BoxThe cloud storage company that picked the IT department as its customer while Dropbox picked the user.
- Box projectionA correction that makes cubemap reflections line up with a room's walls instead of appearing infinitely far away.
- Box-drawing charactersCharacters for single and double lines, corners and junctions that let text-mode screens draw frames and tables.
- Box2DErin Catto's 2D physics library from 2007 — the engine behind Angry Birds and a whole generation of indie games.
- BPDU guardA Spanning Tree feature that immediately shuts down an access port (err-disable) if it receives a BPDU. On a port where only…
- BPE (Byte Pair Encoding)The algorithm that splits text into subwords for almost every language model. Originally a compression method from 1994…
- BPF / eBPFA virtual machine in the Linux kernel running sandboxed programs at defined hooks — no kernel module, no reboot.
- BPI (bits per inch)The number of bits packed along one inch of a track — one of the two axes that together make up areal density.
- Brad SpenglerThe man behind grsecurity, the kernel patches that ran a decade ahead of Linux's own hardening and were eventually locked…
- Brad TempletonThe Canadian who moderated Usenet's biggest joke group, founded ClariNet and later chaired the EFF.
- Braille artText graphics built from Unicode's braille characters, where each character acts as a two-by-four pixel grid.
- Braille embosserThe last stronghold of impact printing: a machine that presses dots up out of heavy paper instead of putting colour on it.
- BrainChipAustralian company whose Akida processor mimics the brain's spiking neurons instead of crunching floating-point.
- BraintreeChicago payments API for apps and web shops, best known for buying Venmo and then being bought by PayPal.
- BranchA parallel line of development in Git — you work on a feature without disturbing main.
- Branch predictionModern CPUs guess which branch of an if is taken and start executing it speculatively. On misprediction, the work is thrown…
- Branch predictorCPU component that guesses the outcome of if/loop branches before the condition is actually evaluated, so the pipeline…
- Branch target buffer (BTB)A cache in the CPU that remembers where previous branches (jumps) led, so the processor can predict the target address of a…
- BraveBrowser, and company, that blocks other people's ads by default and offers its own instead.
- BrazeFires push notifications, email and in-app messages triggered by what a user does in an app — the marketing machinery behind…
- BRDFThe function describing how much light a surface reflects from one incoming direction toward one viewing direction — a…
- BREACH attackA side-channel attack that leaks secrets from encrypted HTTPS responses by measuring how well compression matches guessed…
- Break-glass accessAn emergency access procedure for bypassing the normal access controls in an acute crisis — "break the glass in case of…
- BreakpointOne of the world's largest demoparties, held in Germany since 2000, dedicated to real-time graphics coding, animation, and…
- Breidbart IndexThe formula Usenet used to decide when a mass posting was spammy enough to delete, named after Seth Breidbart.
- Brendan EichWrote JavaScript in ten days in 1995 — a timeframe that has taken the blame for the language's quirks for thirty years.
- Brent WatersAmerican cryptographer who laid the foundations of attribute-based encryption with Amit Sahai and then built most of the…
- Bresenham's line algorithmDraws a straight line on a pixel grid using only integer addition — no floating point, no division.
- BrevoFrench marketing platform for email and SMS that rebranded from Sendinblue in 2023.
- Brewster KahleThe engineer who built WAIS for full-text search on the early internet, then decided someone ought to keep a copy of…
- BrexCorporate cards and spend management built for startups, underwriting on the company's cash rather than the founder's…
- Brian CarrierAmerican researcher and developer behind The Sleuth Kit and Autopsy, the free toolkit most forensics courses start with.
- Brian KernighanWrote the books that taught the world C and the Unix philosophy — and is the K in both K&R and AWK.
- Brian KrebsInvestigative journalist whose blog, KrebsOnSecurity, names cybercriminals so often that they spend real effort trying to…
- Brian ReidThe computer scientist who wrote one of the first document markup systems and then did more than almost anyone to bring…
- Brian SnowAn NSA veteran from the defensive side who spent his career pointing out that features are not the same thing as security.
- Bridgy FedBridge between ActivityPub (Mastodon) and AT Protocol (Bluesky). Ryan Barrett, launched 2024. Mastodon user can follow a…
- BrigadingWhen a group coordinatedly invades another community, thread, or account — to mass-downvote, flood with hostile comments, or…
- BRIN (Block Range INdex)A PostgreSQL index type that stores the minimum and maximum value per group of pages instead of one entry per row. It is…
- BRIN indexBlock Range INdex — a minimal index type in PostgreSQL for large, physically-sorted tables. Stores min/max per N pages…
- British Tabulating Machine CompanyThe firm that sold Hollerith machines under licence across the British Empire, built the bombes for Bletchley Park, and…
- Broad phaseThe first stage of a physics engine's collision search, cheaply discarding object pairs that cannot possibly touch.
- BroadcastSending a packet to everyone on the network rather than a specific recipient.
- Broadcast Channel APIA simple web API for sending messages between tabs, windows, and workers from the same origin. Open a named channel in…
- Broadcast domainThe set of devices that all receive each other's broadcast traffic. A switch (without VLANs) is a single broadcast domain; a…
- Broadcast Wave (BWF)An ordinary WAV file with an extra metadata block saying where in time the audio belongs.
- BroadcastChannelBrowser API that lets tabs, iframes and workers from the same origin talk to each other over a named channel — no server…
- BroadcomMakes the chips inside switches, wifi routers and phones — and has additionally become one of the industry's most methodical…
- BroadVisionThe software that was going to personalise every web shop — and one of the dotcom bubble's steepest descents.
- Broadway (GTK)A GDK backend that displays a GTK program in a web browser instead of on an X or Wayland screen, by pushing frames over a…
- BrocadeThe Fibre Channel switches that wired up data-centre storage networks for two decades.
- Broken Access ControlOWASP Top 10 #1 (2021). Umbrella category: IDOR, missing function-level access control, privilege escalation…
- Brooks's law"Adding manpower to a late software project makes it later." — Fred Brooks, The Mythical Man-Month, 1975.
- BrotherThe Nagoya sewing-machine company whose monochrome laser printers have become the internet's stock answer to "which printer…
- BrotliCompression algorithm from Google (2015) that compresses HTML/CSS/JS ~20% better than gzip.
- BrowserSoftware that fetches and renders web pages. Contains: HTML parser, layout engine, JavaScript engine, CSS engine, network…
- BrowserbaseManaged headless-browser infrastructure for AI agents. Launched 2024. Cloud browsers with Stagehand (AI-friendly…
- BrowserifyThe tool that brought Node's require() to the browser and started the whole bundler era.
- BrøderbundThe sibling-run publisher behind Lode Runner, Print Shop, Carmen Sandiego, Prince of Persia and Myst — an unusually good hit…
- Bruce DangThe Microsoft engineer who took apart Stuxnet's Windows exploits and then wrote the textbook on reverse engineering.
- Bruce SchneierThe cryptographer who wrote the book people actually read — and then spent his career explaining that cryptography doesn't…
- Bruce SterlingScience-fiction author who wrote cyberpunk's manifesto and then the best contemporary account of American police hunting…
- BrunsvigaThe German pinwheel calculator that turned the mechanical adding machine into a mass-market product — sold as a "brain of…
- Brute forceGuessing a password by trying every possible combination until you hit the right one.
- BSD (Berkeley Software Distribution)The Berkeley branch of Unix that gave the world sockets, the TCP/IP stack, and a licence permitting almost anything.
- BSP treeA tree that recursively splits space with planes, yielding a guaranteed depth order for drawing — the trick that made Doom…
- bspwmA tiling window manager in which the screen is a binary tree and every new window splits the focused leaf, driven entirely…
- btoaBinary to ASCII: a 1980s Unix encoder that packed four bytes into five characters and so wasted less than uuencode.
- BtrfsModern Linux filesystem with ZFS-like features: snapshots, subvolumes, compression, RAID mode, checksums. Chris Mason, 2007…
- Bubble memoryThe 1970s' promised universal memory: magnetic bubbles nudged around inside a crystal, with no moving parts and no power…
- Buck / Buck2Meta's build system — Buck1 (2013, Java) is now superseded by Buck2 (2021, Rust). Built for Meta's giant monorepo.
- Bucket-brigade device (BBD)An analog delay chip in which a chain of capacitors hands voltage samples down the line one stage per clock tick, like…
- BufferAllocated memory region for binary data. Used for I/O, network packets, image pixels, audio samples. The term refers to both…
- Buffer overflowWriting past the bounds of a buffer in memory — overlaps neighbours, can lead to arbitrary code execution.
- Buffer poolThe database's own cache of data pages in RAM. Nearly all performance tuning is fundamentally about getting the right pages…
- BufferbloatWhen oversized network buffers turn milliseconds into seconds — the reason your video call stutters the moment someone…
- Bug bountyProgrammes where companies pay for reported security holes — incentive for "ethical hackers".
- BugcrowdThe Australian upstart that made bug bounties a market with two vendors instead of one.
- BugsnagError monitoring that captures crashes and exceptions from apps in production and measures how stable each release actually…
- Build engineKen Silverman's mid-90s 2.5D engine — the rival to Doom's engine, and the foundation of Duke Nukem 3D.
- BuildahRed Hat tool to build OCI/Docker images. Daemon-less, rootless, scriptable. Complement to Podman (run) + Skopeo (registry…
- Builder patternGang-of-Four pattern — build a complex object step by step via a separate builder class instead of a constructor with 15…
- Builder XcessoryICS's GUI builder for Motif, where widgets were dragged from a palette and the code came out as C, C++ or UIL, and the only…
- BuildKitModern Docker build engine. Tõnis Tiigi, 2018. Replaced legacy builder. Concurrent layer building, mount cache, secret…
- Bulkhead patternA resilience pattern that isolates resources into separate "compartments" so that a fault in one part doesn't sink the whole…
- BullFrance's national computer maker, which changed owners more often than operating systems.
- BulletAn open 3D physics engine by Erwin Coumans — as at home in Hollywood VFX as in Blender and robotics simulation.
- Bullet timeA device where game time slows down while the player's control stays responsive, so fast action becomes readable and aimable.
- Bullfrog ProductionsThe British studio that invented the god game with Populous and then turned management into a genre.
- BumbleDating app where only women can start the conversation — founded by ex-Tinder co-founder Whitney Wolfe Herd after a…
- Bump mappingA trick that makes a flat surface look rough by perturbing its normals with a texture instead of adding geometry.
- BunJavaScript runtime. Jarred Sumner, 2021 (v1.0 Sept 2023). Built in Zig, uses JavaScriptCore (Safari engine) instead of V8…
- Bun bundlerBun isn't just a runtime — it includes a bundler (bun build), test runner (bun test), package manager (bun install)…
- BundlerThe tool that collapses hundreds of JavaScript modules into the handful of files a browser is willing to fetch.
- BungieThe Mac studio that made Halo the Xbox launch title and later changed hands between the two biggest console rivals.
- Bunny hoppingChaining jumps and steering in mid-air so the character accelerates well past its normal top speed — a bug that became a…
- bunny.netA Slovenian CDN with a rabbit logo and pricing that lured small sites away from the big providers.
- BunnyCDNSlovenian CDN that built its name on being fast, cheap, and a little bit silly.
- BuoyancyThe upward force that keeps objects afloat, equal to the weight of the fluid they displace — Archimedes' principle, applied…
- Burroughs adding machineThe first calculating machine that printed what it had done — and therefore the first a bank was willing to trust.
- Burroughs CorporationDetroit adding-machine maker that built the most forward-looking mainframe of the 1960s and ended up merged into Unisys.
- Burt KaliskiRSA Laboratories' first chief scientist and the de facto editor of the PKCS standards that nearly all public-key…
- BusCommunication channel between components — everyone talks on the same "line".
- Bus compressionGentle compression on a group or the whole mix bus, so the instruments move as one rather than each on its own.
- Bus factorThe number of people who need to be hit by a bus before the project stops.
- Business Email Compromise (BEC)A fraud where the attacker poses as an executive, supplier, or colleague via email and tricks an employee into transferring…
- Business ObjectsFrench BI company that let finance departments query databases without writing SQL — and which SAP bought rather than build…
- Butler LampsonThe Xerox PARC systems architect who handed security research both the access matrix and the idea of covert channels.
- Butterworth filterThe filter family with the flattest passband maths allows, paid for with a gentler transition into the stopband.
- ButtonPress and ButtonReleaseX11's mouse-button events, which also carry the scroll wheel ever since it was disguised as buttons 4 and 5.
- BYOK (Bring Your Own Key)The customer generates the master key and imports it into the cloud provider's key service, rather than letting the provider…
- Byte8 bits. The base unit for memory, storage and data transfer.
- Byte BattleA live-coding competition where contestants build an effect in TIC-80 in front of an audience, under a hard 256-character…
- Byte-at-a-time attackA classic way to recover a hidden secret under ECB one byte at a time by letting the attacker control the plaintext.
- Byte-at-a-time ECB decryptionAn attack that recovers a hidden string from an ECB-encrypted service one byte at a time, by controlling what lands in each…
- BYTEAPostgreSQL type for binary data — images, encrypted fields, hash values. Default in-row storage with TOAST for large values…
- BytebeatMusic from a single short C expression, evaluated over a counter and sent straight out as audio.
- ByteBoozerA C64 cruncher built for speed: the decrunch is fast enough to run in the middle of a demo without stalling.
- BytecodeIntermediate compilation format — run by a virtual machine rather than directly on hardware.
- ByteDanceThe Beijing company behind TikTok, which worked out before anyone else that a recommendation algorithm can replace the…
- ByteKillerOne of the Amiga's first widely used crunchers, whose decrunch routine was pasted into countless cracked games.
- Byzantine Generals ProblemHow do n generals reach consensus when some of them are actively trying to sabotage the communication? The classical…
- C2 beaconImplant on compromised host that "calls home" to C2 server periodically. Cobalt Strike Beacon is the iconic implementation…
- Paid blue checkThe model where the blue check became a paid subscription (X Premium, formerly Twitter Blue) instead of a free identity…
- SkeetUnofficial Bluesky slang for "post" (tweet equivalent). Tongue-in-cheek name — Bluesky company avoids the term officially…
C
- AWS CloudFrontAWS's CDN — launched 2008. 600+ edge locations globally; integrates with S3, ALB, Lambda@Edge and CloudFront Functions for…
- AWS CloudWatchAWS's observability service — metrics, logs, alarms, dashboards, traces (via X-Ray), RUM, synthetic monitoring. Billed per…
- CSystems programming language. Dennis Ritchie, Bell Labs, 1972. Created to rewrite Unix in a higher level than assembly. The…
- C NewsThe rewrite of Usenet's news software that proved it didn't have to be slow.
- C# (C-sharp)Microsoft's statically typed language for the .NET platform — Anders Hejlsberg (Turbo Pascal, Delphi), 2000. Java-like…
- C++Statically typed multi-paradigm language — Bjarne Stroustrup, 1985, originally "C with Classes". Dominates AAA games…
- C++ coroutinesFunctions that can pause partway through and resume later, introduced in C++20. The language shipped the machinery but…
- C++/CLIMicrosoft's dialect of C++ that speaks directly to the .NET runtime — the glue language when old C++ has to meet new managed…
- C++BuilderBorland's C++ answer to Delphi: drag components onto a form, double-click, write C++ in the event handler.
- C2 frameworkCommand & Control software: operator (red team / attacker) controls remote beacons on compromised hosts. Cobalt Strike is…
- C3 TechnologiesThe Linköping company that turned Saab's targeting technology into the photorealistic 3D cities of Apple Maps.
- C64 DTVAn entire Commodore 64 squeezed into a joystick, with thirty games and a circuit board that practically begged to be modded.
- CA (Certificate Authority)A trusted party that signs TLS certificates so browsers can trust a site is who it claims to be.
- CA TechnologiesComputer Associates, the software company that grew by buying other people's products, laying off the staff and raising the…
- Cabletron SystemsOne of the big networking vendors of the 1990s, slugging it out with 3Com, Bay Networks and Cisco — before it carved itself…
- CacheTemporary storage of data you need often so you don't have to fetch the original every time.
- Cache coherenceThe problem (and the solution) of keeping multiple CPU cores' private caches in agreement about the value at the same memory…
- Cache evictionDeciding what to throw out when the cache is full — the whole difference between a cache that helps and one that just…
- Cache hierarchyThe stacked levels of ever-larger but ever-slower cache between the CPU core and main memory (RAM). Each level is a…
- Cache lineThe smallest unit the CPU loads into cache from RAM — typically 64 bytes on x86, 128 on some POWER. Reading 1 byte = loading…
- Cache missWhen the CPU looks for data in a cache level but doesn't find it there, and is forced to fetch from a slower level further…
- Cache Storage APIA web API (the global caches object) for programmatically storing request/response pairs — primarily used by service workers…
- Cache-timing attackRecovers key material from how long table lookups take, because the processor's cache decides whether an access is a hit or…
- CaddyModern web server written in Go. Matt Holt, 2015. Automatic HTTPS via Let's Encrypt out of the box. Caddyfile syntax is…
- CadenceThe other half of the EDA duopoly, strongest where the circuit turns into geometry and analog electronics.
- Caesar cipherMove every letter three places along the alphabet. That sufficed in 50 BC and suffices for nothing today.
- CAESAR competitionThe open 2013–2019 competition meant to find successors to AES-GCM, which ended with a portfolio rather than a single winner.
- CAF (Core Audio Format)Apple's audio container from Mac OS X Tiger, built to escape the 4 GB ceiling of WAV and AIFF and to hold any format Core…
- CairoThe 2D graphics library with PDF's imaging model that gave GTK, Firefox and half the Linux desktop anti-aliased vectors…
- CAKELinux qdisc: Common Applications Kept Enhanced. All-in-one QoS solution: shaping + fq_codel + DiffServ prioritization + ACK…
- Cake dayThe anniversary of when a Reddit account was registered, marked with a small cake icon next to the username on that day. A…
- CakewalkThe most stubborn DAW in the Windows world – a 1987 MIDI sequencer that has outlived four owners and one shutdown.
- CalckeyThe original Western-oriented fork of Misskey (2022) that later renamed to Firefish (2023). It pushed early on features and…
- CalCompThe company that sold the world's first commercial digital plotter, and whose FORTRAN subroutines became the de facto way to…
- CalDAVAn open protocol for accessing and syncing calendars over the network — the reason your phone can show a calendar that isn't…
- CalderaOne of the first companies to sell Linux to business, and the one that eventually turned into Linux's worst enemy.
- CalendlyThe link that killed the "does Tuesday work? no, Wednesday?" email thread — the recipient just picks a free slot in your…
- CalicoCommon CNI plugin for Kubernetes — handles pod networking and Network Policies.
- CallbackA function you pass as an argument to another function, which calls it later when something happens.
- Callback hellCode where callbacks nest inside callbacks inside callbacks — a right-leaning pyramid that becomes unreadable.
- Callback verifierA BBS feature that hung up and dialled the new user's stated number back before granting the account full access.
- CalVer (Calendar Versioning)Versioning convention based on date instead of semantic meaning. 2024.1.3 = year.minor.patch. Or YY.MM like Ubuntu 22.04…
- Calvin (deterministic DB)An architecture (research paper 2012) for distributed databases that first decides a global order on all transactions and…
- CAM tableContent-Addressable Memory — the specialized hardware memory type that stores the switch's MAC address table and enables…
- CambriconChinese designer of AI accelerators, named after the Cambrian explosion and seen as a domestic alternative to Nvidia.
- Cambridge AnalyticaThe political analytics firm whose Facebook data became the defining privacy scandal of the 2010s.
- camelCaseThe naming convention where words run together and each new word takes a capital — getUserName, humped like a camel.
- CamelliaA Japanese block cipher from 2000 with the same interface as AES, comparable security and a fraction of the users.
- Camera APIWeb API for accessing the camera + microphone. navigator.mediaDevices.getUserMedia({video: true, audio: true}) returns a…
- Camera dead zoneA region of the screen inside which the player can move freely without the camera following; only when the character reaches…
- Camera shakeA brief, directed jolt of the camera that lends weight to hits, explosions and landings — pure game feel that never touches…
- Camera windowAn invisible rectangle in the middle of the screen where the player moves freely — the camera only follows once the…
- Cameron LacroixAmerican who, at 16, dumped Paris Hilton's phone contacts and photos onto the web in 2005 — and was caught again nine years…
- CAN bus (Controller Area Network)Bus protocol for cars and heavy vehicles — Bosch 1983. Replaced hundreds of point-to-point cables with a single 2-wire bus.
- can.*Canada's national Usenet hierarchy, with its own sub-hierarchies for provinces and cities.
- Canary deploymentRelease a new version to a small share of users first (1–5%), increase gradually if metrics look good. Limits the blast…
- CancelbotA program that automatically sent forged cancel messages on Usenet to delete other people's posts, usually spam.
- CancelmooseThe anonymous spam hunter who wiped mass postings off Usenet with forged cancel messages — and then invented a way to stop…
- CandiruIsraeli spyware firm that changed its name more often than its exploits, until Microsoft gave it a nickname of its own.
- CanonThe Japanese camera maker quietly sitting inside the first laser printers to carry HP's and Apple's names.
- Canon CXThe print engine inside both the HP LaserJet and the Apple LaserWriter, and the reason laser printers stopped needing a…
- CanonicalThe company behind Ubuntu, bankrolled by a certificate fortune and known for going its own way more often than the rest of…
- Canonical URLMeta tag that says "this page is a copy of X" — so Google doesn't punish you for duplicate content.
- CanvaDrag-and-drop design for non-designers — social media posters, Instagram stories, presentations, CVs. 220M+ MAU in 2024.
- Canva AI StudioCanva's AI suite — Magic Design (auto-layout from prompt), Magic Write (text-gen), Magic Edit (image-edit), Magic Switch…
- CanvasHTML element for drawing 2D graphics pixel by pixel via JavaScript.
- CAP theoremIn a distributed system you can only have two of three: Consistency, Availability, Partition tolerance.
- Capability-based securitySecurity model: unforgeable "capabilities" (tokens) grant access — not identity + ACL.
- Capacity factorHow much more than its fair share an expert in an MoE model may receive before surplus tokens are simply dropped.
- CapcomThe Osaka company behind Street Fighter, Mega Man and Resident Evil, and one of the arcade era's major hardware makers.
- CapgeminiEurope's largest IT consultancy, built by a man from Grenoble who mostly bought other companies.
- CapstanThe precision-ground shaft that pulls magnetic tape past the head at a constant speed — a tape deck's real engine for timing.
- Capsule colliderA collision shape shaped like a cylinder capped by two hemispheres — the standard body proxy for characters because it…
- Captain CrunchJohn Draper, the man who found that a toy whistle from a cereal box produced exactly 2600 Hz — the tone that opened the…
- CAPTCHA"Completely Automated Public Turing test to tell Computers and Humans Apart" — the test that's supposed to prove you're not…
- Captive portalThe login page that appears at hotels, airports and cafés. The network passes DHCP and DNS but redirects everything else…
- Carbon BlackThe whitelisting vendor Bit9, which became an early EDR player and ended up as a product line inside Broadcom.
- Carbon paperAn ink-soaked interleaf that makes a duplicate in the same stroke that writes the original.
- Card interpreterThe machine whose only job was to print on a card what was already punched into it, so a human could read the deck.
- Card issuerThe bank that gave the cardholder their card, and the one that ultimately says yes or no to every purchase.
- Card not present (CNP)Any card payment where the merchant never sees the card itself, only the numbers printed on it.
- Card on fileA card the merchant keeps for later purchases, which makes one-click checkout and subscriptions possible – and makes the…
- Card printerA printer built for exactly one medium: the 0.76 mm slab of plastic in your wallet.
- Card sorterThe machine that could only sort on one column at a time — and therefore handed the world radix sort, fifty years before…
- Card testingFraud in which stolen card numbers are tried against an online shop with small purchases to sort out which ones still work.
- Card tokenizationReplacing the card number with a surrogate that only works in one specific context, so that stealing it gets you nothing.
- Card verification value (CVV)The short check code that ties a card number to a physical property of the card.
- Card verifierThe punched-card machine that punched nothing at all — it only checked that somebody else had punched correctly, by having a…
- Card-Programmed CalculatorUnit-record equipment cabled together into something that was nearly a computer — and that sold far better than IBM expected.
- Cardan grilleA card with holes cut in it, laid over an innocent-looking letter — only the letters showing through the holes carry the…
- CardDAVCalDAV's sibling for address books — syncing contacts between phone, computer and server over HTTP.
- Cardinality estimationThe planner's guess at how many rows each step will produce. Everything else in the plan follows from it, which makes it the…
- Carl EllisonCryptographer who argued that a certificate should say what a key may do, not who owns it, and wrote the standard to prove…
- Carl LandwehrAmerican researcher at the Naval Research Laboratory who wrote two of the most cited surveys in early computer-security…
- Carl PomeranceAmerican number theorist who invented the quadratic sieve, the method that broke RSA-129.
- Carla (plugin host)An open-source standalone plugin host that runs nearly every audio plugin format side by side — no DAW required.
- Carlisle AdamsCanadian cryptographer, the C in CAST, who then spent decades on the less glamorous job of making PKI actually work.
- Carmela TroncosoThe Spanish researcher who led the effort to keep pandemic contact-tracing apps from becoming surveillance registries.
- Carriage control charactersThe first character of each print line was not data but an instruction about how far to advance the paper before printing it.
- Carrier-grade NATNAT run by the ISP between customers and the internet — on top of the home's regular NAT. Result: the customer has a private…
- Carry mechanismThe perennial headache of the calculating machine: moving a one to the next digit when a wheel passes nine — and making it…
- Carsten HaitzlerThe developer better known as Rasterman, who made the Linux desktop pretty with Enlightenment and then spent fifteen years…
- Cartridge Memory (LTO-CM)A small contactless memory chip in the corner of an LTO cartridge that holds the tape's table of contents, usage history and…
- Cas CremersDutch researcher whose formal protocol-analysis tools find flaws in security protocols before attackers do.
- CAS latency (CL)Column Access Strobe latency — the number of clock cycles between the memory controller requesting a data column and the RAM…
- CASBCloud Access Security Broker — a control layer between users and cloud services (SaaS) that gives visibility and security…
- Cascade cipherSeveral ciphers chained in series with independent keys, an old idea for buying a safety margin.
- Cascade layers (@layer)CSS mechanism that inserts a new step into the cascade above specificity: which layer a rule belongs to is decided before…
- Cascaded shadow mapsSplits the view frustum into near-to-far slices, each rendered into its own shadow map, so a single sun casts crisp shadows…
- Cash drawerThe drawer holding the till is a peripheral of the receipt printer, not the computer — it opens on a current pulse through…
- Cash registerRitty built it in 1879 to stop his bartenders stealing — and founded NCR and the entire checkout industry in the process.
- CasioThe company that built a calculator out of relays, won the pocket-calculator price war, then sold the world's most…
- CassandraDistributed wide-column NoSQL — masterless, linearly scalable, designed for massive write volumes across many data centres.
- Cassette tape (storage)Philips' Compact Cassette from 1963, repurposed in the 1970s and 80s as cheap storage for home computers that couldn't…
- CAST-128A Canadian block cipher from 1996 and for years the default symmetric cipher in PGP and GnuPG.
- CAST-256An AES candidate from Entrust with 128-bit blocks and 48 rounds, which did not reach the final.
- Castlewood ORBCastlewood's 1999 removable 2.2 GB magnetic disk — built by ex-Iomega engineers to beat Zip and Jaz on price, and beaten by…
- Catherine MeadowsMathematician at the U.S. Navy's research lab who made formal analysis of cryptographic protocols something you could…
- Catmull-Rom splineAn interpolating spline that passes straight through every one of its control points — a favourite for smooth camera paths…
- Catmull–Clark subdivisionThe most common subdivision rule for quad meshes, converging to a smooth surface related to bicubic B-splines.
- Cato NetworksIsraeli firm that built a cloud of its own points of presence and sold networking plus security as one service — SASE before…
- Cattle, not petsPets have names and go to the vet. Cattle have numbers and get replaced. Your servers should be cattle.
- CatweaselThe German expansion card that taught PCs to read Amiga and C64 floppies long before flux readers were commonplace.
- CaucusA commercial conferencing system from the mid-1980s that took the ideas of CONFER and EIES to companies and organisations.
- Causal consistencyA consistency model that only guarantees ordering between causally related operations (if A caused B, everyone sees A before…
- CAV (constant angular velocity)The disc turns at the same rate throughout — simple for the mechanism, but the outer tracks hold more than they use.
- CB SimulatorCompuServe's 1980 chat feature, modelled on citizens band radio and often cited as the first public real-time chat service.
- CBBSThe first bulletin board system, launched in Chicago in February 1978 while a blizzard kept the city indoors.
- CBCChains the blocks by XORing in the previous ciphertext — which solves ECB's pattern problem and creates a new one.
- CBC-MACA message authentication code built on CBC mode that is only safe for messages of a fixed length.
- CBDC (central bank digital currency)Digital money that is a direct claim on the central bank – electronic cash, rather than a balance at a commercial bank.
- CBORConcise Binary Object Representation (RFC 8949) — binary format that mirrors JSON's data model but is more compact and…
- CCDA light-sensitive chip that marches charge packets in line to an amplifier — the sensor in scanners, fax machines and early…
- CCD-IK (Cyclic Coordinate Descent)A classic iterative IK solver that walks joint by joint up the chain, rotating each one so the end lands as close to the…
- CCM modeAn AES mode of operation that pairs CTR encryption with a CBC-MAC for authentication.
- CCM*A variant of CCM mode that allows encryption only or authentication only, and that protects traffic in Zigbee and Thread.
- CCPA (California Consumer Privacy Act)California's privacy law (2020) — the US's closest counterpart to GDPR.
- CD ProjektThe Polish company that went from selling imported game CDs at a Warsaw market to The Witcher, Cyberpunk 2077 and DRM-free…
- CD-DA (Red Book)The audio CD specification: uncompressed stereo at 44.1 kHz and 16 bits, set down by Sony and Philips in 1980.
- CD-ROMThe data variant of the audio CD, specified by Sony and Philips in 1985 in the "Yellow Book". 650 MB on a disc when hard…
- CD-ROM modes (Mode 1/2)The Yellow Book split of the CD-ROM sector into Mode 1, with extra error correction, and Mode 2, without.
- CDC (Change Data Capture)Change Data Capture — streaming all DB changes (insert/update/delete) as events without modifying application code. The…
- CDC (Change Data Capture)A pattern for capturing every row change (insert/update/delete) in a database and streaming it as an event to other systems…
- CDEThe Common Desktop Environment, the shared desktop Unix vendors agreed on once they finally stopped squabbling.
- CDLODA terrain scheme that morphs a heightmap's vertices between levels of detail in the vertex shader, so LOD transitions become…
- CDN (Content Delivery Network)A geographically distributed network of servers that delivers content from the one closest to the visitor.
- CDPCisco Discovery Protocol — proprietary L2 discovery since 1994. Predecessor to LLDP. Announces Cisco device info: hostname…
- CedarAWS's open-source policy language — simpler than Rego, formally verifiable with Lean. Powers Amazon Verified Permissions.
- Cedar (Xerox PARC)Xerox PARC's programming environment of the early 1980s, in which the whole screen was a set of tiled windows in two columns…
- Cel shadingRendering that imitates hand-drawn art by quantising light into hard bands and adding inked outlines.
- Celebrity problem (hot key)When a single key (e.g. a celebrity with millions of followers) gets disproportionately much traffic and overloads the…
- CelesticaCanadian contract manufacturer born when IBM spun off its own Toronto factory in 1994.
- Cell towerThe physical structure carrying the mobile network's antennas — and a surprisingly large business in its own right.
- CellebriteIsraeli company whose boxes let police pull everything off a seized smartphone.
- Cellular automatonA grid where each cell updates by a simple rule that looks only at its neighbours — the simplicity breeds surprisingly…
- CelonisThe German company that reads a corporation's ERP logs like an autopsy and shows exactly where its processes get stuck.
- Censor DesignC64 demo group known for the Wonderland series and for demos that make a 1982 computer look underestimated by its own…
- CensysA search engine for whatever actually answers on the internet, born out of the research that made scanning all of IPv4 an…
- Centaur TechnologyA small team in Austin that spent a quarter of a century building x86 chips on a fraction of Intel's budget.
- Center of massThe point where an object's mass can be treated as concentrated — a free body rotates around it, and the physics engine…
- Central Point SoftwareThe Oregon company that started out selling tools for defeating copy protection and ended up supplying Microsoft with its…
- CentrifugoSelf-hosted realtime server written in Go that provides pub/sub over WebSocket without tying your app to a cloud service.
- CentronicsThe parallel interface that became the standard way to connect printers to computers for decades.
- CephDistributed storage system that exposes object, block and file storage from the same cluster — Sage Weil's PhD project…
- CepstrumThe spectrum of the logarithm of a spectrum — a way to spot repetition in the frequency domain, such as pitch and echoes…
- CerebrasAI chip company that builds the Wafer Scale Engine — literally a chip the size of an entire 300mm wafer. WSE-3 (2024): 4…
- CERFnetCalifornia's regional research network, and an early one to let paying customers in the door.
- cert-managerKubernetes controller that obtains and renews TLS certificates automatically. The end of the recurring incident where a…
- CERT/CCThe internet's first coordination centre for security incidents, set up at Carnegie Mellon within weeks of the Morris worm…
- Certificate (TLS / X.509)A digital document that binds a public key to a domain — the foundation of HTTPS.
- Certificate authority (CA)A trusted third party that signs certificates, thereby vouching that a public key belongs to a given domain.
- Certificate pinningHardcode which TLS certificate (or CA) a client should accept — extra security beyond the CA system.
- Certificate TransparencyPublic append-only logs of all issued TLS certificates. Lets domain owners detect mis-issued certificates against their…
- Certifried (CVE-2022-26923)The 2022 vulnerability where any logged-in domain user could request a certificate that made them a domain controller. No…
- Cesar CerrudoThe Argentine researcher who first kidnapped Windows tokens and then showed that traffic lights trusted anyone.
- CEVAARM for signal processors — it licenses DSP and AI cores that sit, unseen, in billions of phones.
- cfb and mfb (X11)The sample server's software routines for drawing into the framebuffer, one for colour and one for monochrome, and the…
- CFSLinux's process scheduler from 2007 to 2023 — it handed out CPU time by always running whichever process had received least…
- CGNAT (Carrier-Grade NAT)NAT operated by the ISP — multiple customers share one public IPv4. A consequence of IPv4 exhaustion.
- cgroup (Control group)Linux kernel feature for limiting, measuring, and isolating resources (CPU, memory, I/O, network) for groups of processes…
- cgroupsControl Groups — a Linux kernel feature that limits and measures resource usage (CPU, RAM, IO, network, PID) per process…
- cgroups v2Control Groups version 2 — the Linux kernel's mechanism for limiting and measuring how much CPU, memory, and I/O a group of…
- ChaCha20Modern stream cipher by Daniel J. Bernstein (2008) — fast in pure software on CPUs that lack AES acceleration.
- ChadThe bits of paper punched out of cards and tape — and the scraps that decided a US presidential election.
- ChafaCommand-line tool that turns images and animations into terminal graphics, from plain ASCII all the way to sixel.
- Chain printerA line printer whose characters ride a horizontal chain looping past a bank of hammers.
- Chain-of-thought (CoT)A prompting technique where the LLM is asked to think step by step before giving the answer.
- ChainalysisThe company that turned Bitcoin's public ledger into an investigative tool, and with it punctured the myth of anonymous…
- ChainguardThe company that sells container images with no known vulnerabilities — built from its own minimal Linux distribution.
- Chakra UIReact component library from Segun Adebayo (2019) — focus on accessibility (every component follows WAI-ARIA), themability…
- Change bufferInnoDB's mechanism for deferring maintenance of secondary indexes whose pages happen not to be in memory. An optimisation…
- Channel FFairchild's Channel F beat Atari to the swappable game cartridge in 1976 — a year before the idea became the industry norm.
- Channel modes (IRC)Single-letter flags that decide who may do what in an IRC channel, set with /mode #channel +flag.
- Channel packingStuffing several unrelated grayscale maps into the R, G, B and A channels of one texture to save memory and texture fetches.
- Channel stripA mixer channel's whole signal path, from input to fader, laid out in one vertical column.
- ChanServThe IRC service that turned channels into something you could register and own, rather than something that belonged to…
- ChaocipherTwo alphabet wheels that reshuffle themselves after every letter — a cipher whose workings stayed secret for 92 years.
- Chaos Computer ClubThe German hacker association founded in Berlin in 1981, which has made a tradition of showing the state how its systems can…
- Chaos ConstructionsSaint Petersburg's demoparty, where the Russian ZX Spectrum scene and the security crowd shared a venue.
- Chaos engineeringDeliberately cause failures in production to test the system's recovery — before something real goes wrong.
- Chaos MonkeyNetflix tool that randomly kills production instances to force the team to build systems that tolerate node failures.
- CharacterA unit of text. Complicated in modern contexts — "character" can mean byte, codepoint, grapheme, or glyph depending on…
- Character controllerA kinematic component that moves a game character through the world with collision but without full rigid-body dynamics, so…
- Character encodingThe rules for turning characters into bytes and back — and the reason it says "Ã¥" where it should say "å".
- Character setWhich characters a column can store and how they're encoded as bytes. Set per database, table or column — and wrong…
- Character Set EditorA tool for redefining bitmap character sets — redesigning how letters and symbols appear — enabling rich graphics from…
- Character.AIConsumer-focused chatbot service — Noam Shazeer (transformer paper) and Daniel De Freitas (Google LaMDA), 2021. Users create…
- Characters per secondThe rating of how fast a character or dot-matrix printer works, given in characters per second.
- Charge inputA special move that needs you to hold a direction for a while, then press the opposite — hold back, press forward, and the…
- ChargebackA forced reversal of a card payment, requested by the cardholder through their bank and open to challenge by the merchant.
- CHARGENCharacter Generator Protocol: a service on port 19 that spews characters until someone tells it to stop.
- Charles BabbageThe mathematician who designed the first computer, secured government funding for it, and left behind drawings rather than…
- Charles BennettThe IBM physicist who, with Gilles Brassard, invented quantum key distribution and then quantum teleportation.
- Charles RackoffThe third name on the paper that invented zero-knowledge proofs, and the man who worked out how few Feistel rounds you…
- Charles WheatstoneEnglish physicist who proposed a digram cipher in 1854, which ended up named after the man who sold it to the military.
- Charles Xavier Thomas de ColmarThe insurance executive who patented the world's first mass-produced calculator in 1820, then let it sit for thirty years…
- Charlie KaufmanThe security architect who wrote the textbook every network engineer read, then cleaned up IPsec's key exchange.
- Charlie MillerFormer NSA analyst who hacked the iPhone first and later, with Chris Valasek, a Jeep doing highway speed.
- CharPadA Windows editor for C64 character sets, tiles and maps, and the default tool for graphics in new C64 games and demos.
- Chart.jsEight chart types, one canvas element and roughly thirty lines of configuration — which is all most projects ever needed.
- ChatbotA program that holds a conversation in text — from ELIZA's pattern matching in 1966 to today's language models.
- Chatbot Arena (LMArena)A leaderboard for language models based on blind pairwise comparisons. Started in 2023 by the LMSYS group at UC Berkeley…
- ChatGPTOpenAI's chatbot, released November 30, 2022. Built on GPT models (3.5, then 4, 4o, 4.1, 5). Triggered the modern LLM era.
- Cheat codeA hidden button sequence or command granting invulnerability, weapons or level select, usually built first as a testing tool.
- CHECK constraintSQL feature: a predicate every row must satisfy. CHECK (age >= 0). Validation at DB level instead of in application code…
- Check digitThe last digit of a barcode or ID number, computed from the rest, that catches most misreads and typos.
- Check PointIsraeli company that turned the firewall into a commercial product and patented stateful inspection.
- Checkerboard renderingShade only every other pixel in a checkerboard pattern each frame and reconstruct the rest from earlier frames — a way to…
- CheckmarxIsraeli company whose source scanner catches SQL injection before it ships, along with a couple of hundred false positives.
- Checkout.comBritish payments platform that rolls acquiring, gateway and processing into a single API — a head-on rival to Adyen and…
- CheckpointThe moment the database flushes all dirty buffers to disk and records how far into the transaction log it has come. After a…
- Checkpoint (database)A point where the database writes out all "dirty" pages (changed in memory but not on disk) to the data files and marks how…
- CheeseCutterAn open-source SID editor that runs on modern machines but writes music for a real C64.
- ChefConfiguration management in Ruby — Opscode, 2009 (now Progress Software). "Cookbooks" contain "recipes" that describe the…
- Chelsea ManningUS Army intelligence analyst who handed roughly 750,000 classified documents to WikiLeaks in 2010 — the largest leak of its…
- Chen Ing-hauTaiwanese student who in 1998 wrote CIH, a virus that wasn't content with wiping data and went after the BIOS as well.
- Chessboard effectAn endless checkered pattern rotating, zooming or receding in perspective — a demoscene staple since the late 80s.
- Chester CarlsonAmerican inventor who created xerography in 1938 — the technology behind the photocopier and the laser printer.
- Chi-squared testA statistical test that compares observed letter counts with expected ones, used to judge whether a text resembles a given…
- Chip MusicMusic genre created with sound chips from home computers and game consoles, recognized for its characteristic electronic…
- Chip RAMThe part of the Amiga's memory the custom chips could reach — and therefore the part that always ran out first.
- ChipdiskA floppy full of chip music with a little browser front-end — the demoscene composer's album release, back before there was…
- ChipkillMemory error correction strong enough to survive an entire DRAM chip on the module failing, not merely the odd bit flipping.
- ChipletCPU/GPU design strategy where the processor is built from several smaller dies (chiplets) on the same package instead of one…
- Chiplet interconnectThe high-speed link that connects multiple chiplets (separate silicon dies) in a package into a working processor. Crucial…
- Chiplet yieldThe main economic point of chiplets: by building a processor from several small dies instead of one large one, yield…
- Chipmunk2DA small 2D physics library in plain C — the other name you heard whenever someone said Box2D.
- Chips and TechnologiesThe California firm that invented the modern chipset and made PC clones cheap to build.
- ChipsetThe chip on the motherboard that ties together CPU, RAM, PCIe, USB, storage — determines the platform's features.
- ChiptuneMusic made with — or in the style of — home computer sound chips, where three channels and a noise generator are the whole…
- chmodUnix command that changes file permissions — read/write/execute for owner, group, other.
- Chocolate RainThe song and video Tay Zonday posted in 2007, where the contrast between a young man and an unexpectedly deep bass voice…
- ChocolateyWindows package manager — choco install firefox. Builds on NuGet + PowerShell. Third-party, older than Microsoft's official…
- ChopChop attackAn attack on WEP that decrypts a packet without knowing the key, yielding enough keystream to forge new packets.
- Chorus (effect)An effect that makes one instrument sound like several by mixing in a copy with a wobbling delay.
- Chosen-ciphertext attackIn a chosen-ciphertext attack, the attacker gets a decryption oracle to decrypt chosen ciphertexts and learns about the key…
- Chosen-IV attackAn attack in which the attacker can predict or choose the initialisation vector and then test guesses against an encrypted…
- Chosen-key attackAn attack model in which the adversary picks the key and hunts for keys that make the block cipher behave non-randomly.
- Chosen-message attackThe attacker gets a system to sign or authenticate messages of the attacker's choosing, then tries to forge something new.
- Chosen-plaintext attackThe attacker gets messages of their own choosing encrypted and studies what comes out.
- Chosen-prefix collisionA collision attack where the attacker picks both starting prefixes and then computes suffixes that give the same hash.
- CHR-ROMA cartridge's graphics memory — the pattern tables holding the actual pixels for tiles and sprites, kept apart from the code.
- Chris AnleyBritish security researcher whose 2002 paper turned SQL injection from a curiosity into a standard tool.
- Chris EagleThe teacher who wrote the manuals for both IDA Pro and Ghidra.
- Chris EvansThe man behind the FTP server with "very secure" in its name and Google's team for finding holes in other people's software.
- Chris GoggansTexan hacker known as "Erik Bloodaxe", a member of the Legion of Doom and later editor of Phrack.
- Chris HadnagyAuthor and consultant who made social engineering its own speciality within penetration testing.
- Chris HülsbeckThe German who gave the Amiga a cinematic voice — Turrican's fanfares and the TFMX player that made 16 bits sound like an…
- Chris InglisLong-serving NSA official who became America's first National Cyber Director in 2021.
- Chris KrebsFirst director of the US agency CISA, fired by tweet after calling the 2020 election the most secure in American history.
- Chris KubeckaAmerican security researcher who led the rebuild of Saudi Aramco's network after the 2012 Shamoon attack.
- Chris PeikertAmerican cryptographer at the University of Michigan who helped make lattice cryptography efficient enough to standardise.
- Chris RobertsSecurity researcher who tweeted about an airliner's systems from his seat in 2015 – and found the FBI waiting at the gate.
- Chris ValasekSecurity researcher who, with Charlie Miller, took control of a Jeep on the highway over the cellular network.
- Chris WysopalL0pht's Weld Pond, who went from testifying before the US Senate to selling code review to the very companies he had once…
- Christien RiouxDilDog of the Cult of the Dead Cow, who wrote a remote-administration tool so good the antivirus vendors called it a trojan.
- CHRISTMA EXECA REXX script that, in December 1987, drew a Christmas tree on the screen while mailing itself to everyone the recipient…
- Christof PaarGerman cryptographer who made embedded security a discipline of its own and built a DES cracker out of FPGAs for a fraction…
- Christopher DomasSecurity researcher who treats the x86 processor as a black box and finds things its makers would rather not mention.
- Christopher KruegelAustrian researcher who built sandboxes for malware and once took over an entire botnet to see what it did.
- Christopher Pile"The Black Baron", the first person in Britain jailed for writing and spreading computer viruses.
- Christopher SoghoianThe privacy researcher who earned an FBI raid for a web page and then built a career explaining surveillance to lawyers and…
- Christopher TarnovskyThe hardware hacker who dissolves chip packaging in acid and reads the secrets straight off the wires with needles.
- ChromaThe easiest vector database to get started with — pip install chromadb, in-process or server mode.
- Chroma keyMaking one specific colour transparent so another image can sit behind it — greenscreen, in everyday terms.
- Chroma subsamplingStoring colour information at lower resolution than brightness — the eye barely notices, and it halves the data.
- ChromagramA spectrogram folded down to twelve rows, one per note of the chromatic scale, regardless of octave.
- Chromatic aberrationA post-process effect that offsets the colour channels slightly to mimic the fringing real lenses show toward their edges.
- ChromeEveryday term for Google Chrome (browser). See the main term google-chrome for full description.
- ChromiumOpen source browser that Google Chrome is built on. BSD license. Base for Chrome, Edge, Brave, Opera, Vivaldi, Arc — so…
- Chronicle QueueUltra-low-latency persistent queue for Java — microsecond writes via memory-mapped files. Built for high-frequency trading.
- Chronological feedA feed that shows posts in pure time order (latest first), without algorithmic reordering. Once the standard on all…
- ChronosphereAn observability platform built by the Uber engineers behind M3 — pitched on cardinality and cost, not just dashboards.
- CHS (cylinder-head-sector)Disk addressing by three coordinates — cylinder, head and sector — that names a physical location rather than a running…
- CHS addressingLocating a block on an old hard disk by its physical coordinates: cylinder, head and sector.
- ChucKAn audio programming language in which time is part of the syntax: you advance the clock explicitly and sound is computed at…
- Chunk loadingStreaming a large world in fixed-size blocks, loading those near the player and unloading distant ones, so memory and cost…
- Chunked LODPre-builds terrain as a quadtree of static chunks and draws the coarsest chunk whose screen error is small enough — made for…
- Chunked prefillSplitting the processing of a long prompt into pieces and interleaving them with ongoing token generation, so one large…
- Chunked transfer encodingHTTP/1.1 mechanism to send a response in pieces without knowing the total size up front — required for streaming.
- ChunkingSplitting long documents into pieces (chunks) before embedding them for RAG.
- Chunking (RAG)Splitting documents into smaller pieces ("chunks") before they're embedded and indexed for RAG. The chunk size is one of the…
- Chunky-to-planar (C2P)A routine that repacks a chunky pixel buffer into the Amiga's bitplane format — the bridge between easy-to-write graphics…
- Church-Turing thesisHypothesis: everything intuitively "effectively computable" can be computed by a Turing machine (or lambda calculus, which…
- CI/CD (Continuous Integration / Continuous Deployment)Automated pipelines that run tests and ship code on every git commit.
- CIA 6526The Commodore 64's I/O chip, handling keyboard, joystick, serial bus, and the timers that drive music and fast loaders.
- CIDR (Classless Inter-Domain Routing)Notation for IP networks: 192.168.1.0/24 means the first 24 bits are the network part.
- CIDR block (Classless Inter-Domain Routing)The "slash notation" for IP prefixes — 10.0.0.0/24 means the first 24 bits are the network, 8 bits of host = 256 addresses…
- CienaUS maker of optical transport gear, best known for turning wavelength-division multiplexing into a product.
- CiliumModern CNI for Kubernetes — based on eBPF, gives networking + observability + security.
- Cindy CohnAmerican lawyer who won the case establishing source code as speech, and who later ran the EFF.
- CinemachineUnity's procedural camera package: you describe what to film, not where the camera goes.
- CipherAn algorithm that encrypts and decrypts data.
- Cipher feedback mode (CFB)A block cipher mode of operation that turns a block cipher into a self-synchronising stream cipher.
- Cipher machineA mechanical or electromechanical device that automated ciphers that had previously been carried out by hand.
- Cipher suiteCombination of cryptographic algorithms for TLS — key exchange + signature + symmetric + MAC.
- CipherSaberAn RC4-based stream cipher that Bruce Schneier published as an open, simple design anyone could implement.
- CiphertextThe encrypted message: what looks like noise to anyone without the key.
- Ciphertext expansionThe gap between plaintext length and ciphertext length, and one of the quantities that cryptosystems quietly let grow.
- Ciphertext stealingA block mode without padding, where the last ciphertext block is borrowed to fill out the final plaintext block.
- Ciphertext-only attackThe attacker has nothing but the encrypted messages – no plaintexts, no access to the encryption.
- CIRC (Cross-Interleaved Reed-Solomon Code)The two-layer Reed-Solomon scheme that lets a CD keep playing through scratches and specks of dust.
- CircleCIHosted CI service from San Francisco that, one January morning in 2023, asked every customer to rotate every secret.
- CircleMUDThe DikuMUD fork that cleaned up the code instead of piling on features, and became the most common starting point as a…
- Circuit breakerResilience pattern — when a downstream service is failing, stop calling it for a while instead of hammering a wounded system.
- Circuit breaker (ops)A resilience pattern that "breaks the circuit" to a dependency that has started failing — stops calling it and fails fast…
- CirculateRequest and CirculateNotifyThe X11 events behind window circulation: raise the lowest obscured window, or send the topmost one to the bottom.
- CirqGoogle's Python framework for building and running quantum circuits — the counterpart to IBM's Qiskit.
- Cirrus LogicChipmaker that went from graphics in half the PCs of the early '90s to being, for practical purposes, Apple's audio chip…
- CiscoThe company that built the internet's plumbing — the routers, switches and certifications an entire profession trained on.
- Citadel (BBS)The BBS that organised discussion into "rooms" instead of menus — a model that is still around.
- citextPostgreSQL extension: case-insensitive TEXT type. 'Alice' = 'alice' returns true. Standard text types are case-sensitive…
- CitrixThe company that taught Windows to run on a server while the user only got the picture.
- CitusPostgres extension that turns ordinary PostgreSQL into a distributed, sharded database.
- CIXA British conferencing system from 1987 that went from dial-up discussion forums to being one of the country's first…
- ClamAVOpen source antivirus. Tomasz Kojm, 2001. Acquired by Sourcefire 2007, then Cisco 2013. Default mail gateway scanner on…
- clamp()A CSS function that takes three values — minimum, preferred, and maximum — and keeps the result within the range…
- ClangLLVM's C/C++/Objective-C compiler frontend — Chris Lattner et al., 2007. Designed for better error messages and a more…
- CLAP (plugin format)CLever Audio Plug-in — an open audio plugin format written by a DAW maker and a synth maker who had grown tired of depending…
- CLARiiONEMC's midrange storage line below Symmetrix, inherited from Data General and eventually merged into VNX.
- ClariNetWire-service news delivered as paid Usenet groups — often described as the first business built on the internet.
- ClarisApple's software subsidiary, meant to go independent and instead turned into FileMaker.
- ClarotyNew York firm that protects cyber-physical systems — industrial control, OT and medical equipment — from network-borne…
- ClassTemplate/blueprint for creating objects in OOP — defines fields (state) and methods (behavior). Instances of a class share…
- Class D amplifierA power stage whose transistors are only ever fully on or fully off, with the music encoded in how long — which makes the…
- ClaudeAnthropic's LLM family — named after Claude Shannon. Comes as Opus (powerful), Sonnet (balanced), Haiku (fast, cheap).
- Claude (Anthropic models)Anthropic's LLM family. Three-tier naming: Haiku (fast + cheap), Sonnet (balanced), Opus (most capable). Versions: Claude 2…
- Claude CodeAnthropic's CLI coding agent — runs in the terminal, reads/writes files, runs shell commands, invokes tools via MCP.
- Claude ShannonFounded information theory in a single 1948 paper — having already, as a student, shown that Boolean algebra describes…
- Claudia DíazSpanish researcher at KU Leuven who made anonymity measurable and later co-founded the Nym mixnet.
- Claudio GuarnieriItalian security researcher who built Cuckoo Sandbox and later the tools that found spyware on journalists' phones.
- Claus-Peter SchnorrGerman cryptographer behind the Schnorr signature — simpler and cleaner than DSA, and patented for nearly twenty years as a…
- ClavisterA firewall maker from northern Sweden whose main selling point is being European in a market dominated by American and…
- Clean ArchitectureRobert "Uncle Bob" Martin's umbrella for Hexagonal + Onion + DDD — the central rule: dependencies point inward toward the…
- CleanfeedA Perl filter that stopped Usenet spam at the door of the server instead of chasing it down afterwards.
- ClearAreaWipes a rectangle of an X window back to its background — and can order up an Expose event for the program itself while it's…
- Clearview AIUS company that built a search engine for faces by scraping billions of photos from social media without asking anyone.
- ClerkLogin and user management delivered as embeddable UI components, aimed squarely at React and Next.js.
- ClevoTaiwanese ODM whose unbranded gaming laptops get resold under a dozen different names.
- CLI (Command-Line Interface)A program you control via text commands instead of buttons.
- Click trackA metronome in the headphones while recording, so every track lands at the same tempo and can be edited on the beat…
- ClickHouseColumnar OLAP database built for billion-row analytics — written in C++, originally for Yandex.Metrica.
- ClickHouse Table EnginesIn ClickHouse you don't pick "a database" — you pick "which table engine" (MergeTree, ReplicatedMergeTree, Distributed…
- ClickjackingUI-redress attack: attacker overlays transparent iframe of target site over fake content. User thinks they're clicking…
- Clickteam FusionA French game engine where logic is built in a grid of conditions and actions rather than in code.
- ClickUp"One app to replace them all" — tasks, docs, goals, whiteboards and chat in a single tool, shipped at a feature pace…
- Client-side decorationsWhen an application draws its own title bar and frame instead of leaving that to the window manager.
- Client-side predictionThe client applies your input immediately and guesses the outcome, instead of waiting a round trip for the server to confirm…
- ClientMessage (X11)The one X11 event the server never generates itself: twenty bytes of free-form payload that clients and window managers send…
- Clifford BerryThe graduate student who built the first electronic computing machine with his own hands, and died before a court ruled that…
- Clifford CocksThe mathematician who invented RSA at GCHQ in 1973, four years before Rivest, Shamir and Adleman, and couldn't mention it…
- Clifford NeumanAmerican computer scientist who helped carry Kerberos off the MIT campus and into an internet standard.
- Clifford StollThe astronomer who in 1986 followed a 75-cent accounting error at Lawrence Berkeley Laboratory to an intruder selling…
- CLIMThe Common Lisp Interface Manager, the Lisp world's 1990s standard for graphical interfaces, in which whatever is printed on…
- ClinksterA small synth engine for 4k intros that sounds good for very few bytes.
- CLionJetBrains IDE for C and C++. Built on CMake integration by default, with a full debugger, static analysis, refactoring.
- Clip gainA level change on an individual audio clip in a DAW, applied before the channel's plugins rather than after them.
- Clip spaceThe coordinate space right after projection, where the GPU clips away whatever falls outside the screen before the…
- Clipboard managerThe program that keeps what you copied alive after the source program closes, and usually holds a history of recent clips…
- ClipmapA mipmap pyramid clipped to a small window around the viewer, so only the resolution needed near the camera stays in memory.
- Clipper chipThe government's attempt to make encryption with a built-in official key the standard — sunk by a 16-bit checksum.
- Clipping (audio)What happens when a signal asks for more level than the format can hold: the peaks are sliced flat and the waveform turns…
- Clock domain crossing (CDC)A signal passing between two parts of a chip clocked by independent clocks. One of the few classes of bug that never shows…
- Clock gatingAn energy-saving technique that turns off the clock signal to parts of a circuit not being used right now. Since dynamic…
- Clock skewThat different servers' clocks show slightly different times, because quartz clocks drift and NTP sync isn't perfect. A…
- ClojureModern Lisp on the JVM. Rich Hickey, 2007. Functional, immutable persistent data structures, concurrency via STM and…
- ClonebotA dozen IRC connections from one person, driven as a single unit — the standard weapon of 1990s channel wars.
- Close FriendsAn Instagram feature for sharing stories (and now posts) only to a hand-picked "close friends" list instead of all…
- Close-down mode (X11)The setting that decides whether an X client's windows and pixmaps vanish when it disconnects, or stay behind in the server.
- CloseWatcherA single API for "the user wants to close this", whether the signal is Escape on a keyboard or the back gesture on a phone.
- ClosureFunction that "captures" variables from its lexical scope. function counter() { let n = 0; return () => ++n; } — returned…
- Closure tablePattern for storing tree structures in relational databases — a separate table with (ancestor, descendant, depth).
- Cloth simulationFabric as a mesh of point masses held together by distance constraints, relaxed every frame until the cloth hangs right.
- CloudCompute, storage and services you rent over the internet instead of owning yourself.
- cloud-initThe de facto standard for configuring a virtual machine on first boot. Originally from Canonical for Ubuntu in the cloud…
- ClouderaThe company that set out to turn Hadoop into an enterprise product, then watched the market move to the cloud while it was…
- CloudflareThe internet infrastructure giant — 300+ data centres globally, handles ~20 % of all web traffic. Started as DDoS…
- Cloudflare WorkersEdge serverless that runs in 300+ Cloudflare data centres — V8 isolates instead of containers gives sub-millisecond cold…
- CloudinaryA cloud for image and video management: storage, on-the-fly transformation and delivery over a CDN.
- CLS (Cumulative Layout Shift)One of Google's Core Web Vitals — measures how much the page "jumps" while loading.
- ClubhouseAudio-only social app — exploded in spring 2021 during COVID lockdowns, collapsed almost as fast.
- Clubhouse (audio)Audio-only social network — exploded in winter 2021 during COVID. Invite-only iOS triggered FOMO. Valued at $4B at peak…
- ClusterA group of servers working together as if they were one unit.
- Cluster analysisLetting the data decide which observations belong together, without anyone having labelled them first.
- Cluster API (CAPI)Creating Kubernetes clusters by describing them as Kubernetes resources. One cluster manages the others.
- Cluster AutoscalerKubernetes component that adds/removes nodes from the cluster based on pod scheduling pressure. If pending pods can't be…
- Clustered indexAn index that determines the physical order the rows are stored in — the table itself IS the index tree, sorted on the key…
- Clustered shadingDividing the view frustum into a three-dimensional grid of cells — along depth too — and giving each cell its own light…
- CLV (constant linear velocity)The disc spins slower as the head moves outward, so data streams past at a steady rate no matter which track is under it.
- CLXCommon Lisp's interface to X: a complete implementation of the X protocol in pure Lisp, with no Xlib underneath, written…
- CMACCMAC is a message authentication code built on a block cipher, and it exists because CBC-MAC cannot handle messages of…
- CMakeCross-platform build generator — Kitware, 2000. CMake doesn't build; it generates Makefiles, Ninja files, Visual Studio…
- CMatrixA terminal program that rains green characters down the screen like The Matrix — with no practical purpose whatsoever, and…
- CMC modeA wide-block mode that encrypts a whole disk sector in one pass, so a change to any single block spreads across the entire…
- CMC-7The European magnetic font for reading cheques, its characters built from seven vertical bars.
- cmdtool and shelltoolSun's two terminal windows, one with scrollback and editable text and one a plain tty: a split that only made sense until…
- CMR (conventional magnetic recording)The ordinary kind of hard-drive recording, where tracks sit side by side without overlapping — a name nobody needed until…
- CMS (Content Management System)Software for creating + managing digital content without writing code. WordPress dominates (~40% of all websites). Classic…
- CMU Coke machineA soda machine at Carnegie Mellon that, from 1982, could be asked over the network whether it had cold bottles — often…
- CMVPThe joint US–Canadian programme that certifies cryptographic modules against FIPS 140, and the reason HSM datasheets list…
- CNAME recordDNS record saying "this domain is an alias for another".
- CNN (Convolutional Neural Network)Neural network specialised for images — uses "filters" that sweep across the image and find patterns.
- CNN (Convolutional Neural Network)Neural network for images and spatial data — uses convolution filters that slide across input instead of fully connected…
- CNOT gateThe two-qubit gate that flips the target if the control is one — and the most common way to create entanglement.
- CoAP (Constrained Application Protocol)HTTP's ideas shrunk to fit a sensor running off a coin cell. Standardized in RFC 7252. The same methods — GET, POST, PUT…
- COBOL (Common Business-Oriented Language)The business language from 1959, produced by the CODASYL committee with Grace Hopper as its driving force. Designed to be…
- Cockroach LabsThe company behind CockroachDB — Spencer Kimball + Peter Mattis (the same GIMP founders!) left Google in 2014 to build…
- CockroachDBDistributed SQL database inspired by Google Spanner — Postgres-compatible wire protocol, transparent sharding…
- CocoaApple's framework for desktop apps on macOS, inherited wholesale from NeXTSTEP — which is why every class name starts with…
- Cocoa TouchApple's umbrella name for the iOS frameworks — Cocoa rebuilt for fingers rather than a mouse.
- CocoaPodsThe dependency manager that held the iOS ecosystem together for over a decade — now in maintenance mode.
- Cocos2d-xThe C++ engine behind a large share of China's mobile gaming boom — barely known in the West, enormous in Asia.
- CodaDocument tool that set out to blur the line between text, spreadsheet and app — bought by Grammarly in 2024.
- CodabarAn early 1972 barcode, self-checking and easy to print — the workhorse of blood banks and libraries.
- Code 11A dense numeric barcode from 1977 used almost solely to label telecom equipment.
- Code 128A compact linear barcode that handles the full ASCII set, not just digits.
- Code 39The first barcode that could encode letters, not just digits — long a standard in industry and defence.
- Code 93A barcode symbology Intermec created in 1982 to pack more data than Code 39 into the same width.
- Code coverageMeasure of how much of the code is executed by tests — typically given as a percentage.
- Code page 437The original IBM PC character set, whose lines and blocks became the entire palette of ANSI art.
- Code reviewWhen a colleague reviews your code before it can be merged — a standard step in a Pull Request.
- Code signingSign executables with a private key so the OS can verify origin + integrity before execution. Windows Authenticode, Apple…
- Code smellPatterns in code that often signal deeper problems — not bugs themselves, but warning signs.
- Code splittingThe technique of splitting an application's JavaScript into several smaller bundles ("chunks") loaded on demand, instead of…
- Code wheelCopy protection made of cardboard: two rotating discs in the game box that you aligned to look up a code the game demanded.
- CodebergNon-profit, Germany-based git hosting with no profit motive — run by an association and powered by Forgejo.
- CodebookA system that replaces whole words, phrases or code groups with predetermined values instead of individual letters.
- Codebook attackIgnoring the key entirely and just building a lookup table of which ciphertext each plaintext block produces.
- CodecCoder–decoder: a pair of algorithms that compresses audio or video on capture and unpacks it on playback.
- CoDel (Controlled Delay)Active queue management algorithm (Kathie Nichols + Van Jacobson, 2012) — drops packets when the queue's dwell time exceeds…
- CodemastersThe British budget label that went from two-quid tapes to racing games with the Formula One licence.
- CoercivityThe magnetic field needed to reverse a material's magnetization — in practice, a measure of how stubbornly a medium holds a…
- CoffeeScriptA language that hid 2010s JavaScript behind indentation and arrows — and then made itself redundant when JavaScript copied…
- Cogent CommunicationsThe discount carrier of the internet backbone, best known for picking peering fights with more or less everyone.
- CognizantAn American IT services firm with an Indian engine room, born as an in-house unit of a credit-reporting company.
- CognosOttawa software company whose reporting and analysis tools became one of the cornerstones of IBM's analytics business.
- Cohen–SutherlandLine clipping with four-bit outcodes that accepts or rejects most lines without a single division.
- CohereCanadian language-model company that skipped consumer chatbots and sells to enterprises instead.
- CohesityThe Nutanix co-founder's second act: doing for backups what Nutanix did for servers — and eventually swallowing Veritas's…
- CoinbaseThe American exchange that turned buying bitcoin into something you do with a debit card in an app.
- Cold boot attackAn attack that reads encryption keys out of DRAM after the machine is switched off, because memory cells keep their contents…
- Cold walletKey storage that has never been connected to the internet — the only thing protecting against a compromised computer…
- ColecoThe leather-goods firm that became a console maker, sold Cabbage Patch dolls, and killed itself with a computer.
- ColimaHigher-level wrapper on top of Lima + nerdctl. Docker Desktop replacement for Mac (+ Linux). brew install colima && colima…
- Colin PercivalCanadian cryptographer who gave us scrypt, the Tarsnap backup service and the first practical warning that hyperthreading…
- Collab postA shared post on Instagram/Facebook where two (or more) accounts are listed as co-authors — the same post appears in both…
- COLLADAAn open XML format for moving 3D scenes between applications, which solved the interchange problem on paper and created a…
- CollationThe rules for how text is compared and sorted. It determines what ORDER BY returns, the order an index is stored in and…
- CollatorThe punched-card machine that merged two sorted decks into one — merge sort performed by sheet metal and rubber wheels.
- CollibraBelgian data-governance platform — catalogs, ownership and rules for who may touch which table.
- Collide and slideA movement algorithm that, on collision, projects the remaining motion along the surface so the character slides along the…
- ColliderThe invisible, simplified shape — box, sphere, capsule or mesh — a physics engine uses to detect contact, almost always…
- Collin MullinerGerman mobile security researcher who showed that a single text message could be enough to take over an iPhone.
- Collision attackFinding two different inputs that hash to the same value, which is easier than finding an input for a given hash value.
- Collision detectionWorking out which of thousands of objects actually touch, without comparing every pair against every other pair.
- Collision domainThe part of a network where two devices can transmit at the same time and cause a collision on the shared medium. A central…
- Collision layerA layer-and-bitmask system that controls which objects are even allowed to collide with one another.
- Collision responseThe step after a collision is detected: actually moving the bodies apart and changing their velocities so the bounce looks…
- Color cyclingAnimation without redrawing a single pixel — the image holds still while you rotate the values in the colour palette and let…
- Color gradingA post-process pass that remaps the frame's colours through a lookup table to set mood — the game engine's answer to a film…
- Color keyOne sacrificial colour that the drawing routine skips — the cheapest way to make a rectangular image look like anything but…
- color-mix()CSS function for blending two colours: color-mix(in srgb, red 50%, blue).
- Colormap (X11)The table that decided which 256 colours could exist on screen at once, and which program got to choose them.
- ColormapNotifyThe X11 event telling a program its colormap had just been loaded into the hardware — or thrown out to make room for someone…
- Colossal Cave AdventureThe first text adventure, written on a PDP-10 in the mid-1970s and copied to every ARPANET machine with a spare terminal.
- ColossusThe world's first programmable electronic computer — classified for so long that others got the credit.
- Colour depthHow many bits are used per colour channel — and therefore how many shades can be reproduced.
- Colour spaceThe definition of what the numbers in an image actually mean as colour — without it, RGB values are just three numbers with…
- Coloured BookThe British academic protocol suite that ran over X.25, named after the colours of the binders its specifications came in.
- Column FamilyData model in wide-column databases: a row has a key plus arbitrary column families, where each family can have different…
- Columnar storageStorage layout: data stored per column instead of per row. Optimal for analytics — query like SELECT AVG(price) FROM trades…
- Columnar transpositionThe plaintext is written in rows under a keyword and read off column by column, in the alphabetical order of the keyword's…
- Columnstore indexAn index that stores data column-wise instead of row-wise, optimized for analytical queries that scan and aggregate single…
- Com HemSwedish cable operator that turned the coax already in apartment-block walls into broadband for a large slice of the country.
- ComalandA 2014 C64 demo usually counted as the platform's technical peak, at least until the next one.
- Comb filterWhat you get when a signal is mixed with a delayed copy of itself: a row of evenly spaced notches in the frequency response…
- ComcastThe biggest cable and broadband provider in the US — and a fixture near the bottom of just about every customer-satisfaction…
- ComfyUINode-graph UI for Stable Diffusion / Flux / Hunyuan / Wan etc. — drag and connect boxes instead of writing prompts in a…
- Command bufferA list of GPU commands recorded ahead of time on the CPU and then submitted to the graphics queue in bulk, rather than…
- Command injectionVulnerability where user input is executed as a command in an underlying shell or OS call.
- Command patternA design pattern that wraps an action as an object, so it can be queued, undone or replayed after the fact.
- Command-and-control (C2)The infrastructure and communication channel an attacker uses to remotely control compromised machines — send commands…
- CommentText in code that's ignored by the compiler/interpreter — for humans.
- Commercial Internet ExchangeThe providers' own meeting point from 1991, built so commercial traffic could steer clear of the government backbone.
- Commodore 128Commodore's last 8-bit machine — three computers in one case, one of them a complete C64.
- Commodore 1541The Commodore 64's infamously slow floppy drive — a whole computer in a box, throttled by a bus bug.
- Commodore 1581Commodore's 3.5-inch disk drive from 1987 — 800 KB on a single disk when the C64 world still lived on 170.
- Commodore 64The best-selling computer model of all time, and the only one whose sound chip has a fan club.
- Commodore BASIC V2The stripped-down BASIC dialect bundled with the Commodore 64 — so limited that every scrap of graphics and sound needed…
- Commodore CDTVAn Amiga 500 disguised as a hi-fi component, complete with CD drive and remote control – and with nobody who wanted to buy…
- Commodore InternationalA typewriter importer that sold more home computers than anyone else, then went under with the most advanced home computer…
- Commodore PETCommodore's first computer, from 1977, with screen, keyboard and cassette deck in a single sheet-metal case.
- Commodore Plus/4Commodore's office-minded 1984 home computer that threw out both the SID and sprites — and flopped for it.
- Commodore SX-64A Commodore 64 with a built-in colour screen and floppy drive in a suitcase – portable in the most optimistic sense of the…
- Common CriteriaAn international framework for having independent labs evaluate security functions, with assurance levels from EAL1 to EAL7.
- Common Cryptographic Architecture (CCA)IBM's API for cryptographic hardware, which decides which operations an HSM permits and how its keys may be used.
- Common LispThe peace treaty that ended the Lisp wars: one dialect every warring camp could live with.
- CommonMarkA strict specification of Markdown, driven by John MacFarlane starting in 2014. It exists because John Gruber's original…
- Community MemoryA terminal in a Berkeley record shop in 1973 that let anyone leave and search messages — the first public electronic…
- Community NotesTwitter's/X's crowdsourced fact-checking (formerly "Birdwatch", 2021). Users write context notes on posts; a note becomes…
- CommvaultA backup vendor with roots in Bell Labs that has spent three decades selling the insurance companies remember only once the…
- ComodoOne of the web's largest certificate authorities, and the source of one of its most embarrassing breaches.
- comp.*Usenet's computing hierarchy — home to languages, operating systems and hardware, and the place where a fair amount of…
- comp.sources.unixThe moderated newsgroup that served as Unix's software distribution channel before GitHub, SourceForge or even widespread…
- CompactionThe background process in an LSM tree that merges several SSTables into fewer, removes overshadowed old versions, and…
- Compagnie des Machines BullEurope's counterweight to IBM was built on patents from a Norwegian insurance engineer who died before a single machine was…
- Compal ElectronicsTaiwan's other giant laptop builder, with Dell, HP and Lenovo as its regulars.
- CompaqThe Houston company that proved you could legally clone the IBM PC, and so turned "PC" from a product into a category.
- CompellentThe SAN vendor whose automatic data tiering tempted Dell into buying the company in 2011.
- Compiled spriteA sprite stored not as pixels but as machine code that writes exactly those pixels — the fastest blit possible, paid for…
- CompilerProgram that translates source code to machine code (or another target form) before execution.
- CompingStitching a single take together from the best bits of many — short for composite, and the reason few recorded singers ever…
- CompizThe compositing window manager that in 2006 made the Linux desktop wobble, spin and catch fire — on an ordinary graphics…
- Complementation propertyA symmetry in DES: flip every bit of both key and plaintext and the ciphertext comes out exactly flipped.
- Complex Number CalculatorBell Labs' relay machine from 1940 could do exactly one thing — arithmetic on complex numbers — and still became the first…
- Complex Number ComputerBuilt to spare the phone network from doing complex arithmetic by hand, and accidentally became the first computer anybody…
- Complexity theoryThe branch of computer science that sorts problems by the time and memory they demand — not by how hard they feel.
- CompoThe contest at a demoparty where sceners pit their productions against each other and the audience votes for a winner.
- Compose keyThe key that merges the next two presses into one character – Compose, apostrophe, e gives é – a DEC inheritance that X11…
- Composite and Constraint widgets (Xt)The two Xt widget classes allowed to have children: Composite, which owns the list and decides their geometry, and…
- Composite extension (X11)The X extension that lets windows render off-screen and be assembled by a separate program — the foundation under every drop…
- Composite index (Multicolumn index)An index over several columns in a specific order. The key is sorted first by one column, then by the next — exactly like a…
- Compositing window managerA window manager where each window renders into its own buffer and the final image is assembled separately — hence shadows…
- Compound colliderA collision shape built from several simple primitives attached to the same rigid body, so a chair can be five boxes instead…
- COMPOUND_TEXTX11's own text encoding for selections and window titles, built on ISO 2022 so that a single string could switch character…
- Compression oracleWhen data is compressed before encryption, the ciphertext length tells an attacker whether their guess resembles the secret…
- Compressor (audio)An effect that turns the volume down automatically when the signal gets too loud, shrinking the gap between quiet and loud.
- ComptometerThe calculator with no crank: the keystroke itself was the power, and a trained operator outran everything else that existed…
- CompunetA British online service for the Commodore 64 whose content came from its own users – and where part of the early demoscene…
- CompuServeAmerica's first big consumer online service — forums, email and chat a decade before the web existed.
- Compute shaderA GPU program that lives outside the graphics pipeline and computes over arbitrary buffers in a grid of threads — the…
- Compute-optimal (Chinchilla scaling)The 2022 finding that the large language models of the day were badly undertrained: parameters and training tokens should…
- Computer Fraud and Abuse Act (CFAA)The 1986 US federal anti-hacking law, written for a world of mainframes and still used against everything from worms to…
- Computer output microfilm (COM)Writing a computer's output straight to microfilm instead of paper, for archives and high-volume reports.
- Computer programmingThe process of writing instructions for a computer to execute. Spans from assembly to natural language via LLM 2024+. The…
- Computer UseAnthropic feature launched October 2024: Claude takes screenshots of desktop, plans mouse movements + clicks + key presses…
- Computer Vision (CV)AI that understands images — object detection, face recognition, OCR, self-driving cars.
- CompuwareDetroit company that built debugging and testing tools for mainframes and, almost in passing, produced Dynatrace.
- Concat KDFNIST's single-step key derivation for shared secrets from key agreement: hash a counter, the secret and some context, repeat…
- ConcatenationJoining two sequences — usually strings — end to end into one.
- ConcurrencyHandling multiple things "at once" — can be parallel (across cores) or just interleaved (one core switching).
- Condenser microphoneA microphone in which a thin diaphragm and a fixed backplate form a capacitor whose capacitance tracks sound pressure.
- ConditionalControl-flow construct where code picks a path based on true/false evaluation. if, else, switch, match, ternary operator.
- Conditional differential cryptanalysisDifferential cryptanalysis against shift-register ciphers, where the attacker picks initialization vectors that force the…
- Cone-twist constraintA ball joint with limits: the limb may swing within a cone and twist a little around its own axis, and no further.
- ConexantRockwell's spun-off chip division, whose silicon sat inside a large share of the world's dial-up modems and whose softmodems…
- CONFERThe University of Michigan's 1975 conferencing system, which split discussion into items with responses underneath — the…
- Confidential computingParadigm where data is not readable by the cloud operator + hypervisor + adjacent VMs. Hardware-TEE-based (SGX, SEV-SNP…
- ConfidentialityThe "C" in the CIA triad — data is only accessible to authorised people.
- ConfigMapA Kubernetes object for storing non-secret configuration (key-value pairs or whole files) separately from the application's…
- Configuration driftWhen the actual infrastructure gradually deviates from what's defined in the code/configuration — usually due to manual…
- ConfigureNotifyThe X11 event reporting that a window has actually changed position, size, border width or place in the stacking order…
- ConfigureRequestThe event that turns an X program's attempt to move or resize its window into an application, which the window manager…
- Conflict resolution (DB)How a distributed database handles the same data being changed in different places at once and diverging. The strategies…
- ConfluentThe company Kafka's creators started after leaving LinkedIn, to sell what they had built for free.
- Confusion and diffusionClaude Shannon's two design principles for ciphers: hide how the key relates to the ciphertext, and smear the plaintext's…
- Confusion matrixThe table that sets a model's guesses against the ground truth. Four cells for a binary problem: true positive, false…
- Congestion controlHow TCP (and QUIC) adjust sending rate to avoid overloading the network — the sweet spot where throughput is max but packet…
- Congestion window (cwnd)The sender's own belief about how much data may be out in the network unacknowledged. One of the two limits that govern…
- Connection poolA set of ready database connections the application borrows and returns instead of opening a new one per query. Almost…
- Connection pooling (DB)The technique of reusing a limited number of database connections for many clients, instead of opening a new connection per…
- Connection setup (X11)The opening exchange on an X connection, in which the client states its byte order and credentials and the server replies…
- ConnectixThe Mac company that sold more memory than your computer had, the first mass-market webcam, and a PlayStation emulator Sony…
- Conner PeripheralsA Seagate co-founder started a rival, sold 3.5-inch drives to Compaq, and merged back into his old company eleven years…
- conntrackLinux kernel feature: tracks state per network flow. Drives stateful firewall (iptables -m state) + NAT (matching incoming…
- Conservative advancementA continuous-collision method that advances two bodies in safe steps — the distance between them divided by their maximum…
- Conservative rasterizationRasterization that counts a pixel as covered the moment a triangle touches it at all, rather than requiring the triangle to…
- Consistent hashingDistribution technique: map both keys and nodes to a ring (hash space 0-2^32). A key is owned by the first node clockwise…
- Consistent hashing (DB)A technique for distributing data over nodes so that when a node is added or removed, only a small fraction of the keys need…
- ConspiracyHungarian demogroup that became shorthand for the 64k intro in the 2000s, best known for Chaos Theory.
- ConstantA named value that cannot change after assignment. Languages differ on compile-time constants vs runtime-immutable bindings.
- Constant transmitter (ENIAC)The way into the fastest calculating machine on earth ran through a card reader doing about two cards a second.
- Constant-time programmingWriting crypto code whose running time and memory access pattern don't depend on secret values, so a stopwatch can't stand…
- Constanze KurzGerman computer scientist and CCC spokesperson whose expert testimony fed into two landmark rulings by Germany's…
- constevalThe keyword for a function that must run at compile time. The missing half of constexpr, which only says it may.
- constexprThe keyword saying something may be evaluated at compile time. On a function it means may, not must — the source of most of…
- Constitutional AIAnthropic's training method where an LLM learns to follow a written "constitution" (set of principles) by critiquing and…
- Constraint solverThe part of a physics engine that keeps the rules — bodies don't interpenetrate, joints hold together, friction slows things…
- Constructable stylesheetsAn API for creating CSS stylesheets in JavaScript as objects (new CSSStyleSheet()) and sharing the same instance across…
- ConstructorA special function that runs when an object is created via new MyClass().
- ConsulHashiCorp's service discovery + key-value store + health checks + service mesh.
- Contact Image SensorA scanner technology where a full-width row of sensors sits close under the paper, without the folded lens system a CCD…
- Contact manifoldThe set of contact points between two touching bodies — a box on the floor touches it at four corners, not at a single point.
- Contact shadowsShort, sharp screen-space shadows that fill the gap where an ordinary shadow map is too low-resolution to capture where an…
- Contact start-stop (CSS)The older parking method, where the read/write heads rest directly on the platter whenever the drive is switched off.
- ContainerAn isolated environment where an application runs with its own dependencies, independent of the host machine.
- Container formatThe file format holding video, audio, subtitles and metadata together — but saying nothing about how the contents are…
- Container queriesCSS media queries based on the parent's size, not the whole viewport.
- Container Runtime Interface (CRI)The standardized interface (a gRPC API) the Kubernetes kubelet uses to talk to a container runtime. Thanks to the CRI…
- containerdContainer runtime that pulls and runs OCI images — what Docker uses under the hood, and the default Kubernetes runtime since…
- ContainersLightweight isolated execution environments. Share the host's OS kernel but have their own filesystem, processes, network…
- Content moderationThe work of deciding what may remain on a platform. It consists of rules, automated classification and human reviewers — in…
- Content warning (CW)A Mastodon/Fediverse feature: hide a post's content behind a short label (e.g. "politics", "food", "spoilers") that the…
- Content-EncodingHTTP header that says which compression was applied to the response — typically gzip, br (Brotli), newer zstd.
- content-visibilityA CSS property that lets the browser skip rendering (layout, painting) of elements that are off-screen, until the user…
- ContentfulGerman enterprise headless CMS that coined the category "API-first content management" — customers include Nike, BBC…
- Context compressionShrinking the retrieved material in a RAG pipeline before it's sent to the model — by filtering out irrelevant parts or…
- Context engineeringThe discipline of filling an LLM's context window with the right info, in the right format, in the right order.
- Context steeringA movement AI that weighs every candidate direction against an interest-and-danger map, instead of summing separate steering…
- Context switchChanging which process runs on a core — save all the state for one, restore it for the other.
- Context windowThe maximum number of tokens an LLM can process at once — prompt plus answer. Everything the model "sees" must fit here. It…
- Context-length extensionThe umbrella concept for getting a model to handle a longer context window than it was originally trained on — without…
- Continuous batchingAn LLM inference technique that dynamically tops up new requests in an ongoing batch as soon as a slot opens — instead of…
- Continuous collision detectionChecks the path an object sweeps between two frames rather than only its end position, so fast objects stop tunnelling…
- Continuous formAn endless paper web with perforated folds and sprocket holes down the edges — the tractor printer's food, torn apart…
- Continuous inkjetAn industrial inkjet that sprays an unbroken stream of drops and steers them electrically — most are recycled.
- Continuous Integration (CI)Every commit triggers an automatic build + test. Prevents multiple developers' work from diverging until it can't be merged.
- ContourIngress controller built on Envoy, whose point isn't the performance but that several teams can share a domain without being…
- Contract testingTests that verify two services agree on their API contract — without spinning up both at the same time.
- Contrastive learningTrain a model to place "similar" things close together in the embedding space and dissimilar ones far apart.
- Control Data CorporationThe Minneapolis company that built the world's fastest computer in 1964 and left IBM's chief asking how thirty-four people…
- Control hazardWhen the pipeline doesn't know which instruction to fetch next because the outcome of a jump (a branch) isn't resolved yet…
- Control message (Usenet)Usenet articles meant to be obeyed rather than read: they told servers to create groups, remove groups or delete posts.
- Control StripThe collapsible strip of tiny buttons in the bottom corner of the classic Mac OS screen, for settings changed more often…
- Control surfaceHardware with physical faders, knobs and transport buttons that drives a DAW — a mixing desk that never touches any audio…
- Controller (Kubernetes)A process that continuously compares desired state with actual state and does something about the difference. Kubernetes is…
- Conventional CommitsConvention for commit messages: type(scope): description — e.g. feat(auth): add OAuth2 support.
- Convergent encryptionEncryption in which the key is the hash of the plaintext, so the same file always yields the same ciphertext and can be…
- Converter code (ENIAC)The 1948 conversion that made ENIAC six times slower and considerably more useful, by moving the program out of the cables…
- ConvexBackend platform where queries and mutations are TypeScript functions — the frontend re-renders reactively when data changes.
- Convex decompositionSplitting a concave mesh into a set of convex pieces so a physics engine can collide against it quickly.
- Convex hullThe smallest convex shape enclosing a set of points — think of a rubber band stretched around nails in a board.
- Convolution reverbReverb made by convolving a sound with a recording of how a real space responds to a short, sharp bang.
- Conway's law"Organisations which design systems… are constrained to produce designs which are copies of the communication structures of…
- CookieA small text string the browser stores for a site and sends with every request to it.
- Cookie prefixSpecial cookie name prefixes that browsers enforce restrictions on. __Secure- requires the Secure flag + HTTPS. __Host…
- Cookie theftStealing a user's session cookies (login tokens) and reusing them to take over the account — without needing the password OR…
- Cooler MasterTaiwanese maker of CPU coolers, PC cases and power supplies, in business since 1992.
- COPACOBANAA low-cost FPGA machine that showed DES keys could be searched with off-the-shelf hardware.
- Copiale cipherA 105-page cipher manuscript from the eighteenth century, cracked in 2011 with statistical techniques borrowed from machine…
- Copper (Amiga)The Amiga's tiny graphics coprocessor that rewrites hardware registers mid-frame — the engine behind raster bars and split…
- COPY (bulk loading)PostgreSQL's command for reading in or writing out large amounts of data in one go. Orders of magnitude faster than running…
- COPY (Postgres)PostgreSQL command for bulk import/export. 10-100x faster than individual INSERTs (one transaction, minimal per-row…
- Copy elisionThe compiler skipping a copy or move entirely and constructing the object directly at its final destination. Since C++17 the…
- Copy partyGatherings where home-computer users showed up with a box of floppies and copied each other's games — the pirate ancestor of…
- Copy protectionThe home computer era's tricks for stopping people copying games, almost all of them cracked within a week.
- Copy-on-writePretending to copy while actually sharing — until someone writes, at which point the copy is made for real.
- CopyAreaX11's blit: copy a rectangle between two drawables entirely inside the server, without a single pixel crossing the network.
- CopyleftLicense strategy: requires derivatives to be distributed under the same license. Ensures free software stays free. GPL is…
- CopylockRob Northen's copy protection for the Amiga and Atari ST — it read an unreproducible track and refused to launch without the…
- CopypastaA block of text copied and pasted over and over across forums and chats. The name is a corruption of "copy paste" and the…
- CopyPlaneCopies a single bit plane out of a drawable and paints it in foreground and background colours — how black-and-white icons…
- Core (CPU core)An independent execution unit inside a CPU — an 8-core CPU can do 8 things at once.
- Core AudioApple's audio architecture in macOS and iOS — the reason an audio interface on a Mac usually works at low latency straight…
- Core memoryMemory made of rings on wire, hand-woven under a microscope — and the reason a crash dump is still called a core dump.
- Core MLApple's framework for running machine learning models directly on the device — no data leaves the phone.
- Core parkingA power-saving technique where the operating system "parks" (makes idle and puts into a deep sleep mode) some CPU cores…
- Core rope memoryRead-only memory in which the program was woven by hand: a wire through the ring meant one, a wire past it meant zero.
- Core Web VitalsGoogle's three key metrics for page performance: LCP (loading), INP (interactivity), CLS (stability).
- CoreDNSDNS server written in Go, plugin-based. Default DNS in Kubernetes since 1.13 (2019), replaced kube-dns. CNCF Graduated. Also…
- CorelA Canadian software house whose CorelDRAW was the dominant vector-graphics package of the 1990s, often the first real…
- CoreMIDIApple's MIDI layer in macOS and iOS, built into the operating system so keyboards and software find each other without…
- CoreOSThe startup that built a Linux distribution purely for containers and wrote etcd along the way.
- CoreWeaveA former New Jersey crypto mine that became one of the biggest clouds for AI training by owning GPUs when nobody else could…
- Corey KallenbergFirmware researcher who showed that a PC's BIOS was a better hiding place for malware than the operating system had ever…
- Cormac HerleyThe researcher who costed out security advice and concluded that the users ignoring it are often right.
- Cornell boxA simple boxed scene — two coloured walls and a light in the ceiling — used since 1984 to test whether a renderer gets…
- CorningThe 1851 glassworks that gave Edison his light-bulb envelope, invented optical fiber, and now sits on your phone screen.
- Corona wireA thin high-voltage wire in laser printers and copiers that charges the drum electrostatically — and gives off the smell of…
- CoroutineFunction that can pause its execution and resume later — cheaper than a thread, more expensive than a function call.
- CorpusA large collection of text used to train language models or analyse language.
- Correlation attackAn attack on stream ciphers where the output correlates with a single shift register, so that register can be solved on its…
- Correlation power analysisPower analysis that guesses one key byte at a time and lets Pearson's correlation coefficient decide which guess matches the…
- CORS (Cross-Origin Resource Sharing)The rules for when a webpage may call another domain's API from the browser.
- CORS misconfigurationWhen an API's Cross-Origin Resource Sharing settings are too lax and let an attacker's website read responses from the API…
- CORS preflightExtra OPTIONS request the browser sends before "non-simple" cross-origin calls to ask the server whether the operation is…
- CorsairFrom cache memory modules to everything that can glow in rainbow colours inside and around a gaming PC.
- Cory DoctorowCanadian-British author and EFF activist who argues that DRM and locked-down devices are a security problem, not merely a…
- COSEThe truce in the Unix wars: the 1993 alliance in which HP, IBM, Sun and USL promised a common desktop and a common API — and…
- cosignSign and verify container images without managing keys — uses OIDC identity ("keyless") backed by a transparency log.
- Cosine similarityThe measure of how similar two vectors are, defined as the cosine of the angle between them: the dot product divided by the…
- Cost-based optimizerQuery planner design where every alternative plan is assigned an estimated "cost" (typically IO + CPU estimate) and the…
- Costin RaiuRomanian malware researcher who ran Kaspersky's GReAT team through the decade when state-built cyberweapons became a…
- CoSyA computer conferencing system from the University of Guelph in Canada, 1983, that became the engine behind both Byte…
- CouchbaseA document database born from the merger of CouchDB and Membase — with a built-in memory cache as its inheritance.
- Coulomb frictionThe dry-friction model game physics rests on: the friction force is at most μ times the normal force and opposes sliding…
- Count-Min SketchProbabilistic data structure to approximate frequencies in a stream — Cormode & Muthukrishnan (2003). Like a Bloom filter…
- Counter-StrikeA mod built by two people in their spare time that became the world's most played competitive game for twenty-five years.
- CoupaCloud service for tracking what a company actually buys — and from whom — before the bill becomes a surprise.
- CouplingDegree of dependence between modules/components. Tight coupling = change in one module requires change in many others. Loose…
- Coupling & cohesionTwo central design principles: loose coupling (modules depend little on each other) + high cohesion (a module does one thing…
- Courier (warez)The person who, in the warez scene, moves fresh releases between topsites the instant they drop — status is measured in…
- Cover tapeA cassette — later a floppy or CD — stuck to the front of a computer magazine, loaded with games, demos and utilities.
- Covering indexAn index that contains all the columns a query needs, so the database can answer the query entirely from the index without…
- Covox Speech ThingA cheap 8-bit DAC that clipped onto the PC's parallel port back when real sound cards were a luxury.
- CoWoSChip-on-Wafer-on-Substrate — TSMC's 2.5D advanced-packaging tech. Multiple chiplets (GPU die + HBM stacks) sit on a silicon…
- cowsayTiny Perl program from 1999 that has an ASCII cow say whatever you pipe into it, framed in a speech bubble.
- Coyote timeA few frames of grace in which the player can still jump just after walking off a ledge.
- CP/MDominant operating system for 8-bit microcomputers 1977–1983. Gary Kildall, Digital Research. Direct predecessor to MS-DOS…
- CPaaSCommunications Platform as a Service — cloud APIs that drop SMS, calls and video into any app without you running telco…
- cPanelThe orange control panel an entire generation met the first time they tried to put a website online.
- CPS (Continuation-Passing Style)Programming style where functions never "return" — instead they take a "continuation" (a callback with "what should happen…
- CPS (NeWS)C to PostScript: the NeWS stub compiler, which made PostScript procedures living in the window server callable as C macros…
- CPU (Central Processing Unit)The computer's brain — the chip that actually executes the instructions.
- CPU cacheFaster-but-smaller memory near the CPU core — hides RAM's 100+ ns latency by keeping recently used data close.
- CPU dieThe physical silicon piece (~1 cm²) that actually contains the CPU circuit. Cut out of a wafer. Modern trend: multiple dies…
- CPU registerThe CPU's fastest storage — 16–32 named positions directly in the CPU core. Word-sized (usually 64 bits). Everything the CPU…
- CQRSCommand Query Responsibility Segregation — separate the write model from the read model so each can be optimised (and…
- Cracking GroupOrganized collective of coders, artists, and musicians who released software modifications alongside original graphics and…
- CrackmeA small program written to be cracked — a legal practice course for anyone learning reverse engineering.
- CracktroThe little intro a cracking crew bolted onto a pirated game — signature, greetings and chip music before the game even…
- Craig CostelloMicrosoft Research cryptographer who made elliptic curves and isogenies fast enough to use – and co-designed SIKE.
- Craig GentryThe cryptographer who showed in 2009 that you can compute on encrypted data without decrypting it – a problem left open…
- Craig HeffnerFirmware researcher behind binwalk and Reaver – two tools that turned home routers into open books.
- Craig NeidorfThe Phrack co-founder who was prosecuted over a document the phone company itself would sell you for thirteen dollars.
- CraigslistThe internet's brutally minimal marketplace — since 1995, redesigned approximately zero times. Housing, jobs, stuff, "missed…
- CrashWhen an application unexpectedly stops working — segfault, uncaught exception, kernel panic, OOM kill. Distinct from "hang"…
- Crash mailFidoNet mail sent straight to the recipient, right now, without waiting for the nightly route — and on the sender's phone…
- Cray ResearchThe Chippewa Falls supercomputer maker whose name meant "fastest computer there is" for a quarter of a century.
- Cray-1A supercomputer shaped like a C so that no wire would be too long, with a sofa around the cooling system.
- CRDCustom Resource Definition — extends the Kubernetes API with new resource types. Combined with a controller, it forms the…
- CRDTConflict-free Replicated Data Type — data structure where multiple replicas can be updated independently and always converge…
- CRDT (DB)Conflict-free Replicated Data Type — a data type designed so that concurrent changes on different replicas can always be…
- CreateNotifyThe X11 event announcing that a new window has just been created as a child of a window you are watching — about the only…
- Creation EngineBethesda's engine behind Skyrim and Fallout 4 — as famous for its moddability as for its persistent jank.
- Creative TechnologyThe Singapore company behind the Sound Blaster, whose sound cards were so dominant that "Sound Blaster compatible" became a…
- Creator economyThe collective name for the platforms and tools that let individuals earn a living directly from their audience, with no…
- Creator fundA pot of money a platform distributes to content creators based on their views/engagement, meant to reward popular content…
- CredentialWhatever proves you're you — username+password, API key, certificate, biometrics.
- Credential GuardWindows feature that moves password hashes out of LSASS into an isolated process behind the hypervisor, so not even SYSTEM…
- Credential stuffingUse leaked username + password pairs from breach A to log into site B — because people reuse passwords.
- Creed & CompanyBritish teleprinter maker whose machines clattered in newsrooms and on telex networks for half a century.
- Crest factorThe ratio between a signal's highest peak and its average level — one number that gives away how hard a sound has been…
- CrewAIPython framework for multi-agent AI — define a "crew" of specialized agents with roles, goals, tools. Open source, rapidly…
- CRI-OContainer runtime built specifically for Kubernetes — minimal, OCI-compatible.
- Crib draggingSliding a guessed piece of plaintext along the ciphertext and watching where it breaks the cipher's rules.
- CRIME attackCRIME guesses secret cookies by watching how encrypted traffic shrinks when compression hits a match.
- CrinklerA compressing linker that made it practical to fit an entire Windows intro into 4096 bytes.
- Cris ThomasThe hacker Space Rogue, a member of the L0pht and one of the seven who testified before the US Senate in 1998.
- Crispin CowanThe researcher who put a canary on the stack and made classic buffer overflows a great deal harder to exploit.
- Cristiano GiuffridaItalian systems researcher at VUSec in Amsterdam, involved in a large share of the past decade's Rowhammer and side-channel…
- Critical bandThe frequency range over which the ear lumps sounds into a single filter, governing both masking and perceived loudness.
- Critical rendering pathThe sequence of steps the browser must go through from receiving HTML to painting the first pixels on screen: parse HTML →…
- Critique-reviseTwo-step process: LLM generates response → second LLM (or same with different prompt) critiques → first LLM revises. Core…
- CRLFThe two control characters — carriage return and line feed — that Windows still sends where Unix makes do with one.
- CromemcoA Silicon Valley S-100 maker whose Dazzler gave the microcomputer its first colour graphics.
- CronThe Linux system for running jobs on a schedule — backups, cleanups, periodic reports.
- Cron expressionSyntax for specifying scheduled runs. 5 fields: minute hour day-of-month month day-of-week. 0 9 * * 1-5 = weekdays at 09:00.
- CronJob (K8s)A Kubernetes object that runs a Job on a schedule, with classic cron syntax. The cloud-native equivalent of a crontab line…
- Cross-attentionAttention where the queries come from one sequence and the keys and values from another. The mechanism that lets a model…
- Cross-encoderNeural network architecture for text similarity that encodes query + document together → more accurate than bi-encoder…
- Cross-origin isolationThe state a page enters by sending two particular headers, required to get back the features Spectre took away from the web.
- Cross-platformCode/applications that run on multiple operating systems (Windows/macOS/Linux) or platforms (web/iOS/Android) without…
- Cross-postRepost of the same content in multiple communities. Reddit has built-in "crosspost" that retains a link to the original…
- Cross-validationSplit ML data into K pieces — train on K-1, validate on 1, rotate. More robust than a single train/test split.
- Crossbar switchTelephony's grid of crossing bars with a contact at every intersection — a topology that outlived the exchange and now sits…
- Crossfade (audio)Fading one sound out while the next fades in, so a splice is heard neither as a click nor as a dip in level.
- CrossfeedA filter that leaks a quieter, delayed copy of each stereo channel into the opposite ear, so headphones sound more like…
- Crossing events (X11)EnterNotify and LeaveNotify, the events the X server sends when the pointer crosses a window boundary — the basis of hover…
- Crossover networkA filter network that splits an audio signal into frequency bands, so the woofer gets the bass and the tweeter gets the…
- CrossplaneKubernetes-based IaC — describe AWS, Azure and GCP resources as K8s objects and let an operator reconcile them against the…
- Crosspost (Reddit)Sharing an existing Reddit post to another subreddit with a preserved link to the original and its creator. It spreads…
- Crowd simulationSimulating the movement of many agents at once so they reach their goals without walking into each other or clumping up.
- CrowdStrikeCloud-based endpoint protection that built an empire on a lightweight agent — and in 2024 took down eight million Windows…
- CrowdStrike outage (2024)The largest IT outage in history: a broken update from a security vendor knocked out 8.5 million Windows machines in one…
- CRT (Cathode-Ray Tube)The classic thick TV/monitor technology — an electron beam lights phosphor dots on a glass screen. Dominated displays until…
- CRTP (Curiously Recurring Template Pattern)The C++ trick where a class inherits from a template instantiated with the class itself: class D : public Base<D>…
- CrucialMicron's consumer brand for SSDs and memory modules, sold directly to end users since 1996.
- CRUD (Create, Read, Update, Delete)The four basic operations most data stores support. Maps directly to SQL (INSERT/SELECT/UPDATE/DELETE) and REST…
- CruncherA program that compresses an executable so it unpacks itself at launch — vital when everything had to fit on one floppy.
- CrunchmaniaAn early-90s Amiga cruncher, liked for fast decrunching that worked as well on data files as on programs.
- CryEngineCrytek's game engine — a graphics benchmark since Far Cry in 2004, and the origin of the question "but can it run Crysis?".
- CryptanalysisThe study of breaking ciphers without the key — cryptography's less polite twin.
- CryptexA mechanical lock with rings of letters, best known from Dan Brown's The Da Vinci Code (2003).
- Crypto AGSwiss cipher-machine maker that was secretly owned by the CIA and the BND for nearly half a century.
- Crypto miningGuessing hash values at enormous scale for the right to append the next block — and collecting a reward for the trouble.
- Crypto officerThe role allowed to configure a cryptographic module and manage its users, but ideally not to use the keys itself.
- Crypto walletA keyring, not a wallet — it contains no coins, only the private keys granting the right to move them.
- Crypto-1The secret stream cipher inside MIFARE Classic cards, used in millions of cards before it was broken.
- Crypto-GramBruce Schneier's monthly security newsletter, sent by email since May 1998.
- CryptogramA short encrypted message, usually a simple substitution cipher, most often found as a newspaper puzzle.
- Cryptographic boundaryThe explicitly defined perimeter in FIPS 140 that determines what belongs to a cryptographic module — and therefore what the…
- Cryptographic Doom PrincipleThe rule of thumb that any cryptographic operation performed before verifying a message's MAC will eventually lead to an…
- CryptographyThe maths behind encryption, signatures and hashing — secure communication even when attackers listen.
- CryptojackingSteal CPU/GPU resources from victims without awareness to mine cryptocurrency (usually Monero due to CPU-mineable). Peak…
- CryptonOne of the AES candidates, designed by Chae Hoon Lim and presented in 1998.
- CryptopalsA set of programming exercises in which you break real cryptography instead of reading about why it can be broken.
- CryptoperiodThe span of time, or amount of data, during which a key is approved for use before it should be replaced.
- Crystal DreamTriton's 1992 PC demo that proved texture mapping and tracker music could be squeezed out of an ordinary DOS box.
- Crystal SpaceOne of the first free 3D game engines, written in C++ from 1997 and for a decade the obvious answer to whether there was an…
- CrytekThe German studio whose games spent a decade as the yardstick for whether a PC was any good.
- CSC (Computer Sciences Corporation)One of the first independent software companies, which started out writing compilers and ended up an outsourcing giant.
- CSDbThe community-run catalogue of the Commodore 64 scene — releases, groups, sceners and parties, at csdb.dk.
- CSG (constructive solid geometry)Build complex solids by adding and subtracting simple ones — union, intersection and difference of boxes and spheres.
- CSI (Container Storage Interface)Standard API for attaching storage to container orchestration — primarily Kubernetes.
- CSIRACAustralia's first computer, the only intact survivor of the first generation anywhere — and the first machine to play music.
- CSNETThe network that let computer science departments without defence contracts into the ARPANET club.
- CSO NameserverThe campus electronic phone book of the pre-LDAP era, with ph as the client and qi as the server.
- CsoundA sound-synthesis language from 1986 that still splits music into an orchestra and a score, exactly as Max Mathews did in…
- CSP (Content Security Policy)HTTP header (or meta tag) that whitelists which resources the browser may load. Strong mitigation against XSS — even if…
- CSP noncePer-request random string that allows specific inline scripts under CSP without needing 'unsafe-inline'. Set the nonce in…
- CSPRNG (Cryptographically secure pseudorandom number generator)A random number generator whose next output cannot be predicted even by someone who has seen every previous one.
- CSR (Client-Side Rendering)When the entire page is built by JavaScript in the browser — the server only sends an empty shell HTML.
- CSRF (Cross-Site Request Forgery)An attack where a malicious site tricks your browser into sending a request to another site you're logged into.
- CSRF synchronizer tokenClassic way to defend against CSRF — a hidden random value in every form, compared server-side.
- CSRF tokenRandom token in a form that proves the request came from your UI — not from an attacker's site.
- CSS (Cascading Style Sheets)The rules that decide how HTML should look — colours, layout, typography, animations.
- CSS :has()The "parent selector" — select an element based on what it contains. article:has(img) matches articles that contain an image.
- CSS anchor positioningA new CSS feature (Chrome 2024) for positioning an element relative to another "anchor" element — e.g. a tooltip or dropdown…
- CSS cascade layers (@layer)A CSS feature (@layer) that lets you group rules into named layers with an explicit priority order. The layer order wins…
- CSS custom properties (variables)Variables built into CSS — declared with --name and used with var(--name). Unlike preprocessor variables (Sass) they live in…
- CSS GridModern CSS layout model for 2D design — rows and columns at the same time.
- CSS HoudiniA set of APIs opening parts of the rendering engine to JavaScript, so developers can extend CSS itself instead of waiting…
- CSS ModulesFile-specific CSS classes via build-time transform. .button in Button.module.css becomes .Button_button_a3b4c in the output…
- CSS nestingNative CSS nesting — write rules inside others, like in Sass: .card { & h2 { color: red; } }.
- CSS selectorsSyntax for picking DOM elements. .btn (class), #id, div p (descendant), div > p (child), :hover (pseudo-class)…
- CSS subgridA CSS Grid feature that lets a nested grid inherit (use) its parent's track definition instead of creating its own. It…
- CSS variables (Custom Properties)Variables straight in CSS: --primary: #4a8, used with color: var(--primary).
- CSV (Comma-Separated Values)Plain-text format for tabular data. Values separated by commas, rows by newlines. RFC 4180 (2005). The most portable data…
- ctagsA tool that scans source code and writes an index of where every function, class and variable is defined. The editor reads…
- CTCPA protocol hidden inside ordinary IRC messages, letting clients talk to each other behind their users' backs.
- CTE (Common Table Expression)SQL construct WITH foo AS (SELECT ...) that lets you name intermediate results in a query.
- CTE (Common Table Expression)A named, temporary result set defined with WITH that exists only for the duration of one query. Makes complex queries…
- CTRTurns a block cipher into a stream cipher by encrypting a counter instead of the message.
- CTR_DRBGA random bit generator built from a block cipher run in counter mode.
- Ctrl-Alt-TestFrench demogroup known for its 64k intros and for Shader Minifier, a tool half the intro scene relies on.
- Ctrl+Alt+Backspace (X11)The key combination that kills the X server on the spot, no questions asked, and that has been off by default since 2009…
- ctwmAn extension of twm that gave X11 multiple workspaces with their own backgrounds, long before that was ordinary.
- cu"Call Unix" — the UUCP suite's terminal program, which dialled another computer and turned your terminal into one of its own.
- CU-SeeMeCornell's 1992 video conferencing program that proved people could see each other over the internet — in greyscale, in a…
- CUA (Common User Access)IBM's 1987 interface guidelines that decreed F1 is help, Alt+F4 closes, the menu bar starts with File and Edit, and Esc…
- CubaseSteinberg's 1989 sequencer that started on the Atari ST and ended up defining how audio software talks to plugins and sound…
- CUBE (SQL)A SQL shortcut within GROUPING SETS that computes aggregations for ALL combinations of the given dimensions. GROUP BY CUBE…
- Cube attackAn algebraic attack that sums outputs over a "cube" of public variables to obtain equations in the key bits.
- Cube mappingA texture of six square faces wrapping a point, sampled with a direction vector instead of UV coordinates.
- CubemapSix square textures arranged as the faces of a cube, sampled with a direction vector instead of ordinary 2D coordinates.
- CUBICLinux default TCP congestion control since 2006. Uses cubic function for window growth — faster recovery after loss on…
- CUDANVIDIA's parallel computing platform and programming model — launched 2006. The moat that made NVIDIA the world's most…
- CUDA CoreNvidia's general GPU exec units. CUDA = Compute Unified Device Architecture (2006). Per SM (Streaming Multiprocessor) live…
- CUDIMMClocked Unbuffered DIMM — a DDR5 module with a small clock driver circuit (CKD) that regenerates the clock signal on the…
- Cue mixA separate mix fed to the musicians' headphones while they record, independent of what the engineer is listening to.
- Cue sheetA small text file describing how a CD is divided into tracks, so a single audio file can reproduce the disc exactly.
- CueCatThe cat-shaped barcode reader given away by the million in 2000 — and the dot-com era's most ridiculed flop.
- Cult of the Dead Cow (cDc)The hacker group that started with absurdist text files on a Texas BBS and ended up releasing a Windows remote-control tool…
- Cumulative Layout Shift (CLS)A Core Web Vital that measures how much the page's content unexpectedly jumps and moves during loading — the annoying…
- CUPSThe printing system that manages printers, queues, and drivers on nearly all Unix and macOS.
- Curie pointThe temperature at which a magnetic material loses its magnetisation — and precisely the physics that lets a MiniDisc be…
- curlThe command-line tool for talking to just about any network protocol — and the library shipping in billions of devices.
- Current loopA serial interface where current flowing — or not — around a loop, rather than voltage levels, carries the signal; the…
- Curriculum learningPresenting training data ordered from easy to hard rather than at random, by analogy with how humans are taught. Works…
- CurryingTransform function of multiple arguments to sequence of single-argument functions. add(a, b) becomes add(a)(b). Default in…
- Cursor (AI editor)AI-first code editor — a fork of VSCode with built-in LLM chat, multi-file edits, "Composer", and Tab autocomplete that sees…
- Cursor (database)A pointer into a result set that lets you fetch rows in portions rather than all at once. It exists because a query…
- Cursor ComposerMulti-file edit feature in Cursor — describe a change in natural language, agent updates files across the project. Launched…
- Cursor font (X11)The font called cursor that every X server carries, in which each mouse pointer is a pair of glyphs: a shape and a mask.
- Curt HerzstarkThe engineer who finished the drawings for his pocket calculator as a prisoner in Buchenwald, because the camp…
- CurtaA handheld four-function calculator the size of a pepper grinder, finished on the drawing board in Buchenwald.
- Curve OptimizerAMD Ryzen's feature for fine-tuning the voltage/frequency curve per core, usually for undervolting. By asking each core for…
- Curve25519The Montgomery curve that underlies X25519 (Diffie-Hellman key exchange) and Ed25519 (signatures) — designed by DJB in 2005…
- Custom ElementWeb standard to define new HTML elements. customElements.define('my-button', class extends HTMLElement { ... })…
- Custom ElementsBrowser API for creating your own HTML tags — customElements.define('my-button', class extends HTMLElement {...}).
- Custom emojiSelf-uploaded emoji that a workplace or community adds beyond the standard set — a load-bearing part of the culture in Slack…
- Custom feed (Bluesky)A selectable, custom feed in the Bluesky app powered by a feed generator. The user can subscribe to many and switch between…
- Customizable select (appearance: base-select)Finally being able to style a <select> with CSS. Sounds trivial, but deletes thousands of lines of accessibility-critical…
- Cut buffers (X11)X's first and crudest clipboard: eight text slots hanging off the root window that anyone could write to and read from.
- CutsceneThe moment the game takes the controller away to tell you something — either as pre-rendered video or played out in the…
- Cutting plotterA plotter that holds a knife instead of a pen and cuts vector shapes out of vinyl, paper or film.
- CV/gate (control voltage)How analogue synths were controlled before MIDI: a voltage sets pitch or another parameter, a gate says when the note sounds.
- CVE (Common Vulnerabilities and Exposures)Global ID system for security holes: CVE-2024-12345.
- CVSS (Common Vulnerability Scoring System)0-10 scale that measures how severe a CVE is.
- CWC modeAn authenticated-encryption mode pairing CTR encryption with a Carter–Wegman MAC, which lost out to GCM almost immediately.
- CWE (Common Weakness Enumeration)Classification system for types of security weaknesses — CWE-79 = XSS, CWE-89 = SQL injection.
- CWISCampus-Wide Information System: the menu-driven university information systems of the pre-web era, with phone directory…
- cwmOpenBSD's own window manager: an evilwm descendant that added a search box for windows and programs, and now ships with…
- CXLCompute Express Link — cache-coherent interconnect on top of PCIe 5.0+. Launched in 2019 by Intel, now an industry standard…
- CXL memoryAttaching RAM via CXL (Compute Express Link) over PCIe lanes instead of traditional memory slots. It enables memory…
- CyberArkIsraeli security company that more or less defined the market for locking up and watching over administrator accounts.
- CybereasonThe Boston-based EDR vendor whose "MalOp" tried to show a whole attack as one story rather than a flood of alerts.
- CyberneticsNorbert Wiener's 1948 science of control and communication in the animal and the machine — it died as a field and survived…
- CyberspaceThe word for the network as a place rather than a tool — invented by a science fiction writer who had barely used a computer.
- Cycling unit (ENIAC)ENIAC's clock, and also its first debugger: the cabinet that broadcast timing to every other unit and could be set to…
- Cyclomatic complexityCounts how many independent paths run through a function — which in practice is the number of if statements plus one.
- CyclometerRejewski's device for cataloguing Enigma's fingerprints: two sets of rotors wired in series and a lamp panel showing how the…
- CydromeThe other 1984 VLIW startup — Bob Rau's modulo scheduling outlived the company and ended up in Itanium too.
- CygwinPOSIX emulation layer for Windows — provides Bash, GCC, grep, ssh and hundreds of other Unix tools running natively on…
- Cygwin/XCygwin's X server, XWin, which has let X programs run on Windows since 2000 — and whose multiwindow mode is the code Xming…
- CylanceThe antivirus company that promised machine learning would make signatures obsolete — and was then fooled by strings lifted…
- Cylinder skewA deliberate offset of the sector numbering between adjacent tracks, so the first block of the next track reaches the head…
- Cynthia DworkThe computer scientist who made privacy measurable with differential privacy — and invented proof of work long before anyone…
- CypressE2E test framework that runs inside the browser — time-travel between steps, hot reload, beautiful UI.
- CyrixThe Texas chipmaker that built cheaper x86 processors than Intel and taught the industry to measure performance in marketing…
- CythonWrite nearly ordinary Python, add type declarations to the five lines that are the bottleneck, compile the lot to C.
- Game crackingThe art of removing copy protection from games and software to enable pirate distribution.
- Google Cloud RunGCP's serverless container service — push a Docker image; Cloud Run scales from 0 to N and bills per request-second.
- Microsoft CopilotMicrosoft's umbrella brand for AI assistants — separate from GitHub Copilot. Primarily driven by OpenAI models via Azure.
- Subtiming tuningManually fine-tuning a RAM kit's secondary and tertiary timing parameters (tRCD, tRP, tRAS, tRFC and more) beyond the…
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- .env file (dotenv)Text file with environment variables for local development: DATABASE_URL=postgres://....
- .NETMicrosoft's development platform — a shared runtime where C#, F# and VB.NET all compile to the same intermediate code.
- .NET MAUIMicrosoft's framework for building apps for iOS, Android, Windows and macOS from one C# codebase — the successor to…
- #[derive] (Rust)Rust attribute that auto-implements traits for structs/enums. #[derive(Debug, Clone, PartialEq, Serialize)]. Standard way to…
- <details> / <summary>HTML elements that give a built-in expander/accordion without JavaScript. <details> hides its content behind a clickable…
- <dialog> elementA built-in HTML element for modals and dialogs. <dialog> with showModal() gives you for free what previously required a lot…
- Amazon DynamoDBAmazon's managed NoSQL — key-value + document, schemaless, autoscaling. Built 2007 internally (for the shopping cart)…
- D-BusThe message bus the Linux desktop, and by now the whole Linux system, talks through: a daemon that relays method calls and…
- D-LinkTaiwanese router maker that shows up in security advisories more often than in product reviews.
- D-WaveSold the world's first commercial quantum computer in 2011 — and has been defending whether it counts as one ever since.
- D* LiteIncremental pathfinding that cheaply repairs a route when the map changes instead of searching again from scratch.
- D3.js (Data-Driven Documents)Low-level JS library for data visualization. Mike Bostock, 2011. Binds data to DOM elements (SVG); the user writes…
- D64 (disk image)The de facto standard for storing a Commodore 64 floppy as a single file.
- DaemonA process that runs in the background with no user interaction — Linux's equivalent of Windows services.
- DaemonSetA Kubernetes object that ensures one pod runs on every (or selected) node in the cluster. Use: log collectors (Fluentd…
- Dafydd StuttardBritish security tester who built Burp Suite, the tool nearly every web pentest runs through.
- DAG (Directed acyclic graph)A graph with directed edges and no cycles — the data structure behind build systems, version control and every pipeline tool…
- DaggerPortable CI/CD engine. Solomon Hykes (Docker creator), 2022. Write pipelines in Go/Python/TypeScript/Java instead of YAML…
- DagsterModern data orchestrator where "assets" (datasets, dashboards, ML models) are first-class objects — not just tasks as in…
- Dahua TechnologyThe world's second-largest maker of surveillance cameras, neighbour to Hikvision in Hangzhou and on US sanctions lists.
- Daily.coWebRTC-based video API that drops group calls into an app with a few lines of code.
- Daisy chainWiring peripherals in a chain — each device has one port in and one port out, and the cable wanders from box to box instead…
- Daisy wheel printerAn impact printer with fully formed letters on the spokes of an interchangeable wheel, built for letter-quality output.
- daisyUIA Tailwind CSS plugin that adds semantic component class names (btn, card, modal) instead of long utility strings.
- DALL·EOpenAI's text-to-image series. Name from Salvador Dalí + WALL·E. v1 January 2021 (12B-parameter GPT-3 derivative). v2 (April…
- DALL·E 3OpenAI's image model integrated into ChatGPT — excellent prompt adherence, GPT-4 expands your prompts automatically.
- DALnetThe 1994 IRC network that made registered nicknames and channels the norm rather than the exception.
- Damage extension (X11)An X extension that reports which parts of a window have changed, so nobody has to repaint everything just in case.
- Damien MillerAustralian developer who since 1999 has made sure OpenBSD's SSH implementation works on every other system too.
- Damien StehléFrench lattice cryptographer whose name is on both algorithms NIST picked as the world's new standards for post-quantum…
- Dan BonehThe Stanford cryptographer who made identity-based encryption practical and gave blockchains their favourite signature…
- Dan EgerstadSwedish security consultant who showed in 2007 that Tor hides who you are but not what you send – by publishing embassy…
- Dan FarmerThe security researcher behind SATAN, the vulnerability scanner that in 1995 convinced half the internet that hackers had…
- Dan GeerThe security researcher who lost his job for likening Microsoft's dominance to a genetic monoculture.
- Dan GuidoThe founder of Trail of Bits, the consultancy that audits other people's code and open-sources its own tooling.
- Dan KaminskyThe researcher who in 2008 found a DNS flaw that let anyone poison a resolver's cache in seconds — and got the whole…
- Dan ShumowThe Microsoft cryptographer who, six years before Snowden, stood on a stage in Santa Barbara and explained exactly how…
- Dan WallachRice University computer scientist who broke Java's security model early on and then spent decades making elections…
- Dancing menA substitution cipher in which each letter is a stick figure in a different pose, from a Sherlock Holmes story by Conan…
- DANE (DNS-Based Authentication of Named Entities)Publish TLS cert fingerprints in DNS via TLSA records — instead of trusting the public CA system.
- DangerThe company behind the Hiptop/Sidekick — a cloud-synced smartphone before the term existed, and the training ground for…
- Daniel BleichenbacherCryptographer who showed in 1998 that RSA encryption with PKCS #1 v1.5 padding could be broken through error responses.
- Daniel GenkinSide-channel researcher who listened RSA keys out of a laptop's whine and then helped find Spectre and Meltdown.
- Daniel GrussThe Graz researcher who helped discover Meltdown — and had already written the fix before anyone knew it was needed.
- Daniel J. Bernsteindjb — wrote the crypto that in practice replaced RSA, and litigated the right to publish it.
- Daniel Kahn GillmorThe ACLU technologist who treats IETF standards work as a civil liberties issue.
- Daniel StenbergThe Swede whose small file-transfer tool sits in an estimated twenty billion-plus devices.
- Daniele MicciancioThe UC San Diego theorist who helped turn lattice problems from a complexity-theory niche into the foundation of…
- Danny DolevIsraeli computer scientist at the Hebrew University whose attacker model with Andrew Yao is still the default adversary in…
- DanteAustralian firm Audinate's protocol for carrying hundreds of uncompressed audio channels over ordinary switched Ethernet…
- DAOAn organisation whose rules live in code rather than in articles of association, and where voting power follows token…
- DAP (Debug Adapter Protocol)The same idea as LSP but for debugging. The editor speaks one generic protocol to an adapter, which in turn drives the real…
- DaprDistributed Application Runtime — a sidecar that gives your app standardised "building blocks" (state, pub-sub, secrets…
- Dark AvengerPseudonym of the Bulgarian virus writer who, around 1990, turned polymorphic viruses into a kit anyone could use.
- Dark modeDark colour palette — easier on the eyes in low light, saves battery on OLED screens.
- Dark patternUX design intentionally crafted to trick the user — hide the cancel button, pre-ticked boxes, fake urgency.
- Dark siliconThe phenomenon that you can no longer power all the transistors on a modern chip at once — it would draw too much power and…
- DarktraceBritish security firm that learns how a network normally behaves and raises the alarm when it stops.
- DartGoogle's language launched in 2011 — originally meant to replace JavaScript in browsers (failed), now the language Flutter…
- DashlaneA French-American password manager that dropped its desktop apps and bet everything on the browser.
- DaskParallel Python — runs pandas/NumPy-like code over a cluster (or more CPU cores locally) by building a task graph and…
- Dassault SystèmesThe French company whose CAD software designs aircraft, cars and ships — spun out of a fighter-jet maker.
- DAST (Dynamic Application Security Testing)Security testing of a running application — send in malicious payloads, see what happens.
- DAT (Digital Audio Tape)A digital audio tape that flopped in the living room but became a workhorse for server backup under the name DDS.
- Data contaminationWhen test data has leaked into the training data. The model then gets the answer right because it memorized the question…
- Data DomainThe company whose inline deduplication made disk cheap enough to replace backup tape — and set off a bidding war between EMC…
- Data encryption keyThe key that encrypts the data itself, while another key encrypts this one.
- Data exfiltrationThe unauthorized removal of data out of an organization — the actual "theft" in a data breach. The attacker copies sensitive…
- Data GeneralMinicomputer maker founded by DEC defectors and remembered mostly for a book about how it built one machine.
- Data hazardWhen an instruction in the pipeline needs a data result that a preceding instruction hasn't produced yet. The most common…
- Data lakeA store where raw data is dumped in its original format and given structure only when somebody reads it.
- Data localityLaying out data in memory to exploit the CPU cache — contiguous arrays over pointer-chasing — because cache misses dominate…
- Data MatrixThe 2D symbology that shrinks to a few millimetres — which is why it's laser-etched onto circuit boards and surgical…
- Data miningHunting for patterns in large datasets — a term statisticians originally used as an insult.
- Data mixtureWhat proportions the different sources should have in a pretraining corpus. One of the most decisive and least published…
- Data scienceCross-disciplinary field: statistics + programming + domain expertise to extract insights from data. "Sexiest job of the…
- Data separatorThe circuit that recovers the clock from an MFM or RLL stream and decides whether a flux transition in a given window means…
- Data structureOrganizing data in memory to make certain operations efficient. Picking the right structure is often the difference between…
- Data VaultA data-warehouse modeling method (Dan Linstedt) built on three object types: Hubs (business keys), Links (relationships)…
- Data warehouseA central database tuned for analysis rather than transactions — historical data from many source systems, collected and…
- Data-driven designDescribing a game's content and behaviour in data files rather than code, so designers can iterate without recompiling.
- Data-oriented designA way of structuring code around how the data actually sits in memory and is read, rather than around objects and…
- DatabaseOrganized collection of data + the system to store/retrieve/update it. Spectrum: simple CSV → clustered multi-region SQL →…
- DatabricksUnified data + AI platform — Matei Zaharia, Ali Ghodsi, Ion Stoica et al. (Berkeley AMPLab), 2013. Commercial home of Apache…
- DatadogSaaS observability platform — Olivier Pomel and Alexis Lê-Quôc, 2010. Metrics + logs + traces + RUM + synthetics + security…
- DataFusionApache project: a Rust-written query engine on top of Arrow — like DuckDB but as a library, not a database, and increasingly…
- DataikuA French platform where data scientists and business users are supposed to build models in the same tool, with varying…
- DataLoaderA JS library from Facebook that solves GraphQL's N+1 problem — batches and caches individual requests within a single tick.
- DatapointThe San Antonio terminal maker whose instruction set, by a roundabout route, became x86.
- DatasaabSaab's computer division in Linköping, which started out crunching numbers for fighter jets and ended up inside Ericsson.
- DatasetThe collection of data an ML model trains on — quality and size matter more than architecture.
- DatasetteCommodore's cassette deck, which stored programs as audio on ordinary tape — cheap, rugged and painfully slow.
- DataStaxThe company that made money from Cassandra, a database it didn't invent but for years effectively steered.
- Date & time (DateTime)"Date and time is hard." Time zones, daylight saving, leap seconds, calendar changes — all have bitten developers.
- Datex-PWest Germany's public X.25 network, and the route by which a generation of German hackers reached the rest of the world.
- DattoBackup and disaster-recovery vendor aimed at IT service providers rather than at end users directly.
- Dave AitelThe former NSA computer scientist who turned exploits into shelf-ware with a support contract.
- Dave KennedyAmerican penetration tester who wrote the Social-Engineer Toolkit and turned phishing into something you launch from a menu.
- Dave SmithThe synth designer who built the Prophet-5 and proposed the interface that became MIDI.
- David ChaumThe cryptographer who invented most of online anonymity before there was much of an online to be anonymous on.
- David D. ClarkThe MIT researcher who was the internet's chief architect in the 1980s and showed that banks need a different security model…
- David Elliott BellMITRE mathematician who, with Leonard LaPadula, created the Bell–LaPadula model, the foundation of military computer…
- David GoldschlagThe third name behind onion routing — the US Navy researcher who, with Michael Reed and Paul Syverson, wrapped network…
- David JaoUniversity of Waterloo mathematician who designed SIDH in 2011 – isogeny-based key exchange that looked like the most…
- David JeffersonLawrence Livermore computer scientist who in 2004 helped get the Pentagon to scrap its internet voting system weeks before…
- David KahnAmerican historian whose 1967 book The Codebreakers made the history of cryptology readable to non-specialists.
- David L. SmithNew Jersey programmer who released Melissa in March 1999, the macro virus that showed what Word and Outlook could achieve as…
- David LitchfieldBritish database security researcher whose published SQL Server exploit became the basis of the SQL Slammer worm in 2003.
- David MaynorThe researcher whose MacBook hack at Black Hat 2006 became one of the industry's nastiest disputes over responsible…
- David MazièresStanford professor who co-wrote bcrypt with Niels Provos and later designed the Stellar consensus protocol.
- David NaccacheCryptographer who carried theory from ENS down into the chip on your bank card, and back again.
- David PointchevalFrench cryptographer who gave random-oracle signature schemes a real security proof by rewinding the attacker and making it…
- David S. H. RosenthalThe programmer who wrote X11's rules of conduct for window managers, built NeWS with Gosling, and then spent twenty years…
- David WagnerBerkeley cryptographer who broke Netscape's SSL as a grad student and has been finding holes in everything from phones to…
- David WheelerInvented the subroutine call, wrote the world's first program library, and then coined the industry's most-quoted axiom.
- David WhittakerOne of the most prolific game composers of the 1980s, with music for hundreds of titles on the C64, Spectrum and Amiga.
- Davies–Meyer constructionA way to build a hash function's compression step out of a block cipher.
- Davies' attackA known-plaintext attack on DES that exploits the uneven distribution of outputs from adjacent pairs of S-boxes.
- DaVinci ResolveHollywood-grade video editing + colour grading + audio post + VFX in one app. The free version is wildly capable. $295…
- DAWDigital audio workstation — the program where music is recorded, edited, mixed and mastered, and which replaced both the…
- Dawn SongBerkeley professor whose research has drifted from searchable encryption and binary analysis to blockchains and the security…
- DAWprojectAn open file format for moving a whole music project between DAWs, including tracks, clips, automation and plugin settings.
- Daytime ProtocolConnect to port 13 and get the date and time as a line of human-readable text — in a format nobody ever agreed on.
- DBE (Double Buffer Extension)Double buffering for ordinary X windows, so animations stopped flickering without dragging in OpenGL.
- dBFSDecibels relative to full scale — the measure of digital audio level, where the ceiling is zero and everything else is…
- dbt (data build tool)SQL-based transformation tool — writes the T-step of ELT as modular SELECT statements with Jinja templating, dependency…
- dBuA decibel scale for analogue signal voltage, with 0.775 volts as its zero point.
- dbx noise reductionDavid Blackmer's tape noise reduction: compress the whole signal 2:1 on the way in, expand it 1:2 on the way out, and let…
- DC blockerThe smallest useful filter in audio DSP: a zero at 0 Hz and a pole right next to it, removing DC and leaving everything else…
- DC offsetWhen an audio waveform swings around a constant shift above or below zero instead of around zero itself.
- DCC (Direct Client-to-Client)The IRC extension that lets two clients talk directly to each other instead of through the server. The basis of all file…
- DCOPKDE 2 and 3's own message bus, the Desktop COmmunication Protocol, which let every KDE program be driven from the command…
- DCShadowRegistering your own machine as a domain controller, pushing changes in via replication, and then deregistering. DCSync in…
- DCSyncPretending to be a domain controller and asking the real ones to replicate the password database. No code runs on the…
- DCTCP (Data Center TCP)A TCP congestion control variant built for data centers, presented by Microsoft Research in 2010. It uses ECN marks to…
- DDA (digital differential analyzer)Draws a line by stepping along one axis and adding the slope to the other — simple, but with floating point.
- DDD (Domain-Driven Design)Design philosophy from Eric Evans (2003) — model the code after the business domain's language and rules.
- DDD (Domain-Driven Design)Eric Evans (2003) — model complex domains by talking with domain experts and mirroring their language directly into the code.
- DDGI (Dynamic Diffuse Global Illumination)A grid of light probes that gets re-ray-traced a little every frame, so indirect lighting can change in real time instead of…
- DDL / DMLTwo categories of SQL commands: DDL (Definition: CREATE, ALTER, DROP) and DML (Manipulation: SELECT, INSERT, UPDATE, DELETE).
- DDoS (Distributed Denial of Service)Many computers simultaneously flood a server with requests so it dies under the load.
- DDoS amplificationDDoS technique: attacker sends a small UDP query with spoofed source = victim's IP to a public server that replies with a…
- DDP (Disc Description Protocol)The format a finished CD master is delivered to the pressing plant in: audio, track layout and codes in a set of files.
- DDRThe standard for computer RAM — DDR4 is common now, DDR5 is the newcomer.
- DDR memory controller (IMC)CPU-integrated unit that drives DDR memory access — until mid-2000s sat in the northbridge chipset, today inside the CPU die.
- DDR44th generation DDR-SDRAM. Mainstream 2014-2022. Speeds 2133-3200 MT/s default (overclocking to 4800+). Replaced by DDR5 in…
- DDR5 (Double Data Rate 5)Fifth-generation DDR RAM — double the bandwidth of DDR4, on-die ECC, lower voltage.
- DDR5 overclockingRunning DDR5 memory faster than JEDEC standard, either via ready-made EXPO/XMP profiles or manual tuning of frequency…
- DDS (Digital Data Storage)The data-backup format that borrowed DAT's 4 mm helical-scan tape and became a server-room workhorse from 1989 on.
- DDSP (differentiable DSP)The idea of letting a neural network drive classic synthesis building blocks instead of generating every sample itself.
- De-esserA compressor that only listens for "s" sounds, and tames them before they slice into the listener's ear.
- de.*The German-language Usenet hierarchy — bigger than most national hierarchies and more regulated than most international ones.
- Dead reckoningExtrapolating a remote player's position from its last known position and velocity between packets — borrowed from the…
- Dead zoneA region near an analog stick's centre where small movements are ignored, so wear and skew don't drive the character when…
- Dead-letter queue (DLQ)A separate queue where messages are moved when they can't be processed after a certain number of attempts. Instead of a…
- DeadlockWhen two threads wait for each other forever — A holds lock 1 and waits for 2, B holds lock 2 and waits for 1.
- Deadlock (database)Two transactions waiting on each other's locks — the database has to abort one of them.
- Deadlock detection (DB)The mechanism that detects when two (or more) transactions are waiting on each other's locks in a circle and can never…
- DEALAn AES candidate that built on DES to get larger blocks and longer keys.
- DebeziumOpen-source CDC platform — reads Postgres/MySQL/SQL Server/Mongo/Oracle logs and publishes each row change as a Kafka event.
- DebianOne of the oldest Linux distros — Ian Murdock, 1993 (the name: Deb + Ian). Entirely community-driven, incredibly…
- Debug drawAn API for drawing throwaway lines, boxes and text straight into the game world, making invisible logic visible.
- DebuggingFinding + fixing defects in code. Term from Grace Hopper 1947 (literal insect in the Harvard Mark II relay). Tools…
- DECThe inventor of the minicomputer — the company whose PDP and VAX put computers within reach of individual departments, and…
- DEC (Digital Equipment Corporation)The maker of the minicomputer and, for two decades, the world's second-largest computer company — swallowed by Compaq just…
- DecalA small texture projected onto existing surfaces to add detail — bullet holes, blood, tire marks, graffiti — without…
- DecibanTuring's logarithmic unit for how strongly an observation supports a hypothesis.
- DecibelA logarithmic comparison between two quantities — not a unit of loudness, even though that is how it gets used most.
- DecimaGuerrilla's engine behind Killzone and Horizon — and the one Hideo Kojima borrowed after leaving Konami.
- Decimalization table attackAn attack that recovers a bank PIN in about fifteen calls by feeding an HSM doctored decimalization tables.
- Decision treeClassic ML algorithm: tree structure where each internal node is a feature test, each leaf is a decision. Interpretable, no…
- Declarative partitioningSplitting a table by a key value with actual syntax instead of with inheritance, triggers and constraints. Arrived in…
- Declarative programmingParadigm: describe what you want, not how. Opposite: imperative (step-by-step). SQL, HTML, CSS, Prolog, Terraform, regex are…
- Declarative Shadow DOMA way to create Shadow DOM directly in HTML markup (via <template shadowrootmode="open">) instead of only via JavaScript. It…
- DeclippingAudio restoration that reconstructs the waveform peaks lost when a recording was driven into clipping.
- DECnetDEC's in-house network architecture, linking PDPs and VAXen well before TCP/IP was the obvious choice.
- Decode stageThe step where fetched instructions are interpreted and translated into the internal micro-operations (µops) the CPU's…
- DecoherenceThe quantum state leaking into the environment and turning classical — the single biggest reason quantum computers are hard…
- DecollatorA machine that splits a multipart continuous form into separate paper webs and pulls out the interleaved carbon paper.
- DecoratorA function or annotation that wraps another function/class to add behaviour.
- Decorator patternGang-of-Four structural pattern — wrap an object and add functionality around it without modifying the original class.
- Decorrelation theoryA framework for proving that a block cipher resists whole classes of attacks by measuring how far it sits from a truly…
- DECtermThe DECwindows terminal emulator: a VT300-class terminal in a window, with ReGIS and sixel graphics, for VMS users who would…
- decvaxDEC's VAX in New Hampshire, one of the busiest relay points in the early UUCP network.
- DECwindowsDEC's graphical environment for VMS and Ultrix, one of the first commercial desktops built on X11.
- DECwriterDEC's hardcopy terminal, the machine that retired the Teletype as the default console — a dot matrix printer with a keyboard…
- Dedicated servoAn older scheme where a whole platter surface carried nothing but positioning tracks, followed by a head of its own while…
- Deep CrackThe sub-$250,000 machine that proved in 1998 what officials had been denying: DES could be broken by brute force.
- Deep learningMachine learning with deep neural networks (many layers). Breakthrough: AlexNet 2012 won ImageNet by a wide margin →…
- Deep linkA link that opens a specific view in an app rather than its home screen — spotify:track:... rather than merely "open…
- DeepfakeAI-generated video/audio where a person's appearance or voice is swapped out — often without consent.
- DeepMindBritish AI lab, bought by Google in 2014, known for AlphaGo and AlphaFold.
- DeepSeekChinese AI lab (Hangzhou) founded 2023 by Liang Wenfeng. Releases open-weight LLMs that shocked the market with…
- DeepSeek-R1Chinese open-weights reasoning model (DeepSeek, January 2025) that matched OpenAI o1 on maths and coding — for about…
- DeepSIDBrowser-based SID player that makes the whole of HVSC browsable and playable without installing anything.
- DeepSpeedMicrosoft's training library for PyTorch, released in 2020 together with ZeRO. It made training models with hundreds of…
- Default gatewayRouter IP that a host sends packets to when the destination isn't on the local subnet. Typically 192.168.1.1 or 192.168.0.1…
- Default routeThe route used for all traffic whose destination doesn't match any more specific entry in the routing table — "send…
- Defect listA drive's register of sectors that must not be used — those the factory found, plus those that failed later in service.
- DefederationWhen a Fediverse instance breaks all federation with another — users on the two servers can no longer see or interact with…
- Defense in depthSecurity principle: multiple independent layers of defence — if one fails, the next holds.
- Defensive programmingCoding style: assume all input is hostile, every API call fails, anything can return null.
- deferLanguage feature: defer execution of an expression until the enclosing function returns. Guarantees cleanup regardless of…
- Deferred shadingSeparating geometry from lighting: draw all the surface data into a buffer first, then compute the light afterwards, once…
- DeFiFinancial services built as smart contracts rather than as banks — lending, exchange and derivatives with no intermediary.
- DefleMaskThe multi-chip tracker that speaks Mega Drive, SID, Game Boy and NES in one program — and exports to each chip's own format.
- DefoldA Swedish, 2D-first engine that King bought, used in-house and then gave away.
- DefragmentationMoving a file's scattered blocks back together so they sit in a row, sparing the head from jumping back and forth.
- Degas EliteThe Atari ST's defining paint program, whose file formats became the de facto standard for images on the machine.
- DegausserA device that uses a strong alternating magnetic field to reset a whole medium's magnetisation at once — bulk-erasing tapes…
- DehomagIBM's German subsidiary leased punched card machines to the Third Reich, and remains the clearest reminder in computing…
- Deja NewsThe search engine that turned Usenet into a permanent record, to many people's surprise and some people's horror.
- DekatronA gas-filled tube that counted to ten by making a neon glow hop one cathode further with every pulse — a visible decimal…
- Delaunay triangulationA triangulation that maximises the smallest angle by ensuring no point lies inside any triangle's circumscribed circle.
- Delay (audio effect)An effect that plays back a delayed copy of the signal, usually with feedback so the echo repeats and decays.
- Delay line memoryMemory in which the bits are not stored but travelling: sound pulses sent through a tube of mercury and fed back in when…
- Delayed ACKTCP feature: wait up to 200 ms before sending an ACK in order to combine it with outgoing data or the next ACK. Saves ACK…
- Delegate (C#)A type-safe function pointer: a variable that holds a method and can be called as though it were the method.
- DeliciousThe bookmarking service that taught the web to tag, then changed hands until nothing was left.
- DeliddingCarefully prying off the CPU's metal lid (IHS, the heat spreader) to replace the subpar thermal interface material between…
- DelilahTuring's portable voice scrambler: forty kilos instead of SIGSALY's fifty tons, finished just in time for the war to end.
- DeliTrackerThe Amiga's universal music player, able to play almost any scene format through plug-in replay modules.
- DellThe PC maker whose real product was its supply chain rather than its computers.
- Dell WyseThin clients whose only job is to display a desktop that runs somewhere else.
- DelphiObject Pascal-based RAD tool from Borland 1995. Visual GUI builder + fast compiler. Dominated Windows desktop development in…
- Delta compressionSends only the fields that changed since the client's last acknowledged snapshot instead of the full world state every tick.
- Delta LakeOpen-source storage layer from Databricks — adds ACID transactions, time travel and schema enforcement on top of Parquet…
- Delta snapshotIn multiplayer netcode, sending only the difference from a previously acknowledged snapshot instead of the full world state…
- Delta timeThe time elapsed since the previous frame, used as a multiplier so motion runs at the same speed regardless of frame rate.
- Delta-sigma modulationThe principle behind almost every audio converter made today: very few bits, an enormous sample rate, and a feedback loop…
- Deluxe PaintElectronic Arts' 1985 paint program, which became the games industry's standard tool for pixel art and the Amiga's showcase.
- Demo effectA graphics or visual technique used in demos to create "wow" moments — often built on clever mathematical tricks to squeeze…
- Demo Music Creator (DMC)An early-90s C64 music editor written by Brian of the Hungarian group Graffity — the tool a whole generation of scene…
- DemogroupThe named crew — coder, graphician, musician, swapper — under whose banner demos, cracks and art are released.
- DemopartyAn event where the demoscene gathers to release productions and compete in compos, judged by audience vote on a big screen.
- DemosceneA subculture competing to wring impossible graphics and music out of limited hardware — with programs that serve no purpose…
- DemotoolAn in-house editor in which a demo is assembled on a timeline rather than hard-coded in the source.
- DemozooThe cross-platform demoscene database — productions, groups and party results across every platform, at demozoo.org.
- DemucsMeta's open model for splitting a finished mix into vocals, drums, bass and everything else — now the de facto engine behind…
- Denise (Amiga)The Amiga's display chip — the one that turned bitplanes into pixels, sprites and colours on screen.
- Dennard scalingRobert Dennard (IBM, 1974): as transistors shrink proportionally, voltage + power density drops — faster chips without…
- Dennis RitchieCreated C and helped build Unix — two things that together form the foundation of nearly all software running today.
- DenoJavaScript + TypeScript runtime. Ryan Dahl (Node creator), 2018. Built in Rust + V8. Anti-Node-mistakes: secure-by-default…
- Deno DeployEdge hosting for Deno apps — V8 isolates in 35+ regions. Comes with built-in KV database and queues.
- Denormal numbersFloats so close to zero that the CPU drops into a slow path — the classic reason a silent reverb eats your processor.
- DenormalizationDeliberately duplicating data to avoid joins on read. A trade: faster queries against more complicated writes and the risk…
- DentroThe demoscene's word for a production bigger than an intro but not claiming to be a full demo.
- DeoxysAn AEAD family built on a tweakable block cipher with AES rounds, and first choice for defence in depth in the CAESAR…
- DependabotGitHub's automated dependency updater — opens PRs when your packages have new versions or security holes.
- DependencyAn external library or package your code relies on.
- Dependency confusionSupply-chain attack: register a package on public npm/PyPI with the same name as an internal company package — the package…
- Dependency Injection (DI)Instead of a class creating its dependencies itself it has them passed in from outside.
- Dependent typesTypes that depend on values. Enables expressing invariants in the type system: Vec n Int = vector of exactly n integers…
- DepenetrationThe step that pushes two already-overlapping bodies apart along the shortest way out, before their velocities are resolved.
- DeployMoving code from development to production so users can see it.
- Deployment (Kubernetes)The most common workload type in Kubernetes. You describe the desired state — this pod template, three replicas — and a…
- Depth of fieldMimicking a camera lens's focus: whatever lies in the focal plane is razor-sharp, the rest blurs softly.
- Depth peelingA multi-pass technique for correct transparency that peels off one visible layer at a time, nearest to farthest.
- Depth prepassA first render pass that fills only the depth buffer, so the expensive colour pass never shades a pixel that ends up hidden.
- DereverberationComputing a room's reverb back out of a recording — the inverse of adding reverb, and considerably harder.
- DESThe standard that encrypted the world's cash machines for twenty years, with a key length the NSA insisted on shortening.
- DES-cryptThe 1979 Unix password function built on DES, which only looked at the first eight characters of a password.
- DeschedulerComponent that throws out pods that ended up in the wrong place, because the Kubernetes scheduler decides placement once and…
- Descriptor setA bundle of resource handles — buffers, textures, samplers — that a shader accesses, bound to the pipeline in one go rather…
- Deserialization attackWhen reading "data" from an untrusted source executes arbitrary code — Java serialization, Python pickle, PHP unserialize.
- Desert DreamAmiga demo by the Danish group Kefrens from 1993, one of the best-loved on the platform.
- Design by contract (DbC)Programming philosophy: every function has formal pre-conditions, post-conditions and invariants.
- Design patternA reusable solution pattern for a common programming problem.
- Design patternsReusable solutions to common design problems in OOP. Codified by the "Gang of Four" (Gamma, Helm, Johnson, Vlissides) in…
- Design systemCoherent collection of design tokens (colors, typography, spacing) + components + documentation + guidelines. Ensures…
- Desk accessorySmall programs such as a calculator, a note pad and an alarm clock that could be opened from the Apple menu while a real…
- Deskbar (BeOS)BeOS's combined launcher, window list and status tray, tucked into a small panel in the top-right corner of the screen.
- DeskMateTandy's desktop shell for its own computers in the 1980s — for many American households the first encounter with menus and…
- DeskproCompaq's office desktop from 1984 — and the model that beat IBM to the 386 in 1986.
- DeskSetSun's application suite for OpenWindows, from File Manager and Mail Tool to Calendar Manager and Snapshot, which gave OPEN…
- Desktop cubeVirtual desktops mapped onto the faces of a cube you spin with the mouse — Compiz's signature act, and the window system's…
- Desktop entry (.desktop file)The small text file that makes a program show up in the menu — name, icon, command and category — in a format KDE and GNOME…
- Desktop environmentThe bundle on top of the window system: window manager, panel, file manager, settings, session management and a shared…
- Desktop metaphorPretending the screen is a desk with papers, folders and a wastebasket — the longest-lived simile in the industry.
- Desktop Window Manager (DWM, Windows)Windows's compositing window manager since Vista: the dwm.exe process that draws every window to its own surface and…
- Desktops (Sysinternals)Sysinternals' virtual desktops for Windows from 2008, unusual for being built on the kernel's real desktop objects, which…
- DESQviewText-mode multitasking for MS-DOS, years before Windows could do the same thing usefully.
- DESQview/XQuarterdeck's 1992 attempt to turn a DOS PC into an X workstation: an X11 server on top of DESQview, giving DOS programs…
- DestroyNotifyThe X11 event delivered when a window has been destroyed, with CreateNotify as its counterpart at the other end of the…
- Destructible environmentGame worlds where walls, floors and buildings can actually be blown apart, rather than just swapping in a scorch-mark…
- DestructorA function that runs when an object is destroyed — releases resources (file handles, sockets, memory). Opposite: constructor.
- DESXRon Rivest's cheap extension of DES: XOR an extra key in before and after, and brute force suddenly becomes hopeless.
- Desync (IRC)The state in which the servers of an IRC network no longer agree on what a channel looks like — who has ops, which modes and…
- Detail textureA high-frequency, tightly tiled texture blended in up close to hide the fact that the base texture goes blurry when the…
- Deterministic databaseA database where the same set of transactions, run in the same order, is guaranteed to give exactly the same result on every…
- Deterministic encryptionAn encryption scheme where the same plaintext always produces the same ciphertext, which leaks more than most people expect.
- Deterministic simulationA game loop engineered to produce bit-for-bit identical results from the same inputs on every machine — the precondition for…
- Deus Ex MachinaC64 demo by Crest and Oxyron that won at X'2000 and still ranks among the platform's finest.
- Deutsche TelekomEurope's largest telecoms operator, grown out of the old German postal monopoly and now best known for its magenta colour…
- DEV.to (Forem)Community-driven blogging platform specifically for developers — Medium without a paywall, more wholesome tone.
- DevcontainerReproducible dev environment as container. Specification from Microsoft, open standardized. devcontainer.json defines image…
- Developer consoleA command line built into the game that drops down over the screen and lets anyone who knows what they're doing change…
- Developer unitThe unit that brushes toner onto a laser printer's drum — the step between charging and fusing in the xerographic process.
- DevGuideSun's interface builder for OpenWindows around 1990, which drew OPEN LOOK windows and generated XView code from a…
- Deviant OllamAmerican physical security specialist who reminds IT people that the best firewall won't help if the server room door opens…
- Device Configuration Overlay (DCO)An ATA feature that shrinks a drive's reported size and can hide sectors below the visible end — handy for makers, suspect…
- DevinCognition AI's "autonomous AI software engineer" — receives a task, plans, runs shell commands in a sandbox VM, debugs and…
- DevOpsCulture and practice for merging development (Dev) and operations (Ops).
- DevpacHiSoft's assembler package, carried over from the 8-bits into the 16-bit era, where it became the default tool for machine…
- DevpostPlatform for hackathons — host competitions, submit projects, form teams. Powers Major League Hacking + corporate hackathons…
- DevSecOpsDevOps with security baked into the entire pipeline — instead of "security" as a separate team at the end.
- DevToolsThe browser's built-in developer tools — F12, or "Inspect Element".
- DEXAn exchange that is a smart contract rather than a company — you trade directly from your own wallet.
- DexedOpen-source Yamaha DX7 emulation that reads the original's sound banks and has an interface that finally makes FM synthesis…
- DFS (Depth-First Search)Graph traversal algorithm — go as deep as possible along each branch before backtracking. Implemented recursively or with a…
- DFS (Depth-First Search)Graph traversal that goes as deep as possible before backtracking — implemented with a stack (or recursion).
- DGA (Direct Graphics Access)The XFree86 extension that let a program seize the whole framebuffer and the mouse, bypassing the window system, for…
- DGDDworkin's Game Driver: an LPC driver written from scratch, designed so a world never has to be restarted.
- DgraphDistributed graph database, written in Go. Manish Jain (ex-Google), 2016. GraphQL as the primary query language. Focus on…
- DHCP (Dynamic Host Configuration Protocol)The protocol that automatically assigns IP addresses to devices on a network.
- DHCP relayFunction on a router/L3 switch that forwards DHCP packets between client subnet and DHCP server in another subnet. Cisco…
- DHCP snoopingSwitch feature that filters DHCP responses from non-trusted ports. Protection against a rogue DHCP server that hands out…
- DHCPv6IPv6 version of DHCP — RFC 8415. Uses UDP/546-547 (server-client) instead of UDP/67-68 like DHCPv4.
- DHCPv6 PD (Prefix Delegation)DHCPv6 feature where the ISP delegates a whole prefix (typically /56 or /48) to the customer's home router. The router then…
- DI boxA small box that turns the unbalanced output of a guitar or keyboard into something a microphone input can take.
- Diablo 630The daisy-wheel printer whose control codes spread so widely that "Diablo 630 emulation" was a word-processor standard for…
- Diagonal boardGordon Welchman's addition that turned Turing's Bombe from an experiment into a production tool.
- DialnormA number in the Dolby bitstream's metadata stating how loud the dialogue sits, so the decoder can turn the programme down to…
- Dialogue treeAn in-game conversation modelled as nodes holding lines of dialogue and edges holding the player's possible replies.
- DialpadCraig Walker's third phone company — the one where he had to buy his own name back from Yahoo.
- Diamond MultimediaThe San Jose board maker that put other people's graphics chips in handsome boxes, and accidentally won the lawsuit that…
- Diamond TicketA Golden Ticket for those who care about not being seen: instead of forging a ticket from scratch, you request a genuine one…
- Diamond-square algorithmGenerates fractal terrain by repeatedly setting a midpoint to the average of its neighbours plus a shrinking random offset.
- diaspora*A decentralized social network started in 2010 by four students at New York University as an explicit reaction to Facebook's…
- diaspora* (pod)One of the first decentralized social networks (2010), conceived as a privacy-friendly Facebook alternative. Servers are…
- DICESwedish studio that went from Amiga pinball to Battlefield, and built an engine half of EA was then told to use.
- Dictionary attackDon't try every possible password — try only the ones humans actually choose.
- DID (atproto)Decentralized Identifier — W3C standard ID format. AT Protocol uses did:plc (Public Ledger of Credentials) as default +…
- DiDi (滴滴出行)China's Uber — 600M+ users. Bought Uber's China business in 2016. NYSE IPO in June 2021, force-delisted by Chinese…
- Die shrinkManufacturing an existing chip design on a smaller/newer process node, so the transistors get smaller. The result: lower…
- Die yieldFraction of functional chips per wafer. 90% yield = of 100 dies, 90 work. Larger dies → lower yield (one defect = whole die…
- Diebold NixdorfATM maker that started out building safes in 1859 and moved on to machines that hand money out rather than lock it away.
- Dieter GollmannAustrian security researcher whose textbook Computer Security has been required reading for a generation of students.
- diffThe Unix tool that computes the minimal difference between two text files — and thereby the foundation of every version…
- Difference distribution table (DDT)A table that shows how often an S-box turns a given input difference into a given output difference.
- Difference EngineA machine of brass gears that could compute mathematical tables using nothing but addition — and still consumed the largest…
- Differential analyzerA room-sized assembly of shafts and gears that solved differential equations by physically performing them — computing in…
- Differential characteristicThe path an input difference takes through a cipher's rounds, together with its estimated probability.
- Differential cryptanalysisBreaks ciphers by feeding in pairs with a known difference and watching what the difference becomes on the far side.
- Differential fault analysisAn attack that induces errors during a cipher's computation and compares correct and faulty outputs to recover the key.
- Differential gearA gear train whose output is the sum of two inputs — the adding element of mechanical analog machines.
- Differential power analysisA 1998 side-channel attack that finds key bits in hardware by statistically comparing power consumption across many…
- Differential privacyA mathematical guarantee that the output of an analysis looks almost the same whether or not any one person's data is…
- Differential-linear attackA hybrid where a differential part covers the start of a cipher and a linear part covers the end, sometimes reaching further…
- Diffie-Hellman (DH)Algorithm for establishing a shared secret over an insecure channel — without ever sending the secret.
- Diffusion modelGenerative AI model trained to progressively remove noise from data. The inverse process — add noise to a clean image →…
- dig (domain information groper)The query tool for DNS, distributed with BIND. It shows the entire answer exactly as it came from the server — flags…
- DiggA news aggregator started in 2004 by Kevin Rose. Users submitted links and voted — "digg" or "bury" — and whatever got the…
- Digi sampleThe trick of squeezing digitised sound out of the SID by hammering the volume register faster than the chip was built for…
- DigiBoosterAmiga tracker that picked up where ProTracker left off and let the module grow past four channels.
- DigiCertUtah certificate authority that inherited VeriSign's old certificate business after Google stopped trusting Symantec.
- DigiNotarDutch certificate authority that went bankrupt in 2011, weeks after an attacker walked out of it with hundreds of forged…
- Digital IslandThe dot-com era's number two CDN, bought with billions in stock and sold for a fraction a year later.
- Digital RealtyA property company that happens to own a large share of the world's data centres and rents out floor space, power and…
- Digital ResearchThe company behind CP/M, the first standard microcomputer operating system — and the star of the most retold deal that never…
- Digital signal processor (DSP)A processor tuned to multiply and accumulate streams of samples in real time.
- Digital signatureAsymmetric cryptography proving a message comes from the right sender and hasn't been altered.
- Digital-to-analog converter (DAC)The circuit that turns a stream of sample values back into a voltage a speaker cone can follow.
- DigitalOceanSimplified cloud for developers — calls VPS instances "Droplets", flat monthly pricing, tutorial library that dominates…
- DigitizerA pad with a pen or puck that reports absolute coordinates — how drawings and maps were fed into the computer before the…
- DigramA pair of two letters, the unit cryptanalysts use to read the statistical fingerprint of a language.
- DijkstraClassic algorithm for the shortest path from a source to all other nodes in a graph with non-negative edge weights — Edsger…
- Dijkstra mapA grid pathfinding technique that floods distances from the goal across the whole map, so any number of agents navigate by…
- DikuMUDThe MUD engine from the University of Copenhagen that made classes, levels and monster grinding the default template for…
- Dilly KnoxThe classicist who broke German naval ciphers in one world war and the Abwehr's Enigma in the next.
- Dilution refrigeratorThe cooling rig that holds superconducting qubits at around 15 millikelvin — colder than intergalactic space.
- DIMM slotSlot on motherboard for Dual Inline Memory Module. Consumer mobo: 2-4 slots. Server mobo: 8-32 slots. Number of slots ×…
- Dino Dai ZoviExploit writer who won the very first Pwn2Own by taking over a MacBook through the browser.
- Dionysus BlazakisThe researcher who showed that a JIT compiler can be talked into writing the attacker's machine code for him.
- Dir artArt made inside the directory of a Commodore 64 disk, where filenames and block counts become pixels.
- Direct die coolingRemoving the CPU's metal lid (IHS) entirely and mounting the cooler directly against the silicon die. It removes two heat…
- Direct manipulationThe principle that you change things by handling them on screen rather than by describing the change in words — Ben…
- Direct monitoringThe audio interface feeds its input straight to the headphones before the signal ever reaches the computer, and the latency…
- Direct multiplicationMultiplying in a single pass instead of by repeated addition — by building the multiplication table itself into the machine.
- Direct thermalA printing method where a hot printhead darkens heat-sensitive paper directly, with no ink, ribbon or toner at all.
- DirectFBThe graphics library that gave embedded Linux windows, alpha blending and hardware acceleration straight on the kernel…
- Directional lightLight that falls in one direction at uniform strength everywhere, standing in for a distant sun.
- DirectSoundWindows' audio API from the first DirectX, built to let games talk almost directly to the sound card.
- DirectXMicrosoft's API collection for games on Windows, of which Direct3D is the part that actually matters.
- DirectX plugin (DX/DXi)A Windows-specific format for audio effects and instruments from the late 1990s that lost out to VST.
- Dirty COWCVE-2016-5195 — race condition in Linux kernel's Copy-On-Write handling. Local privilege escalation: write to read-only…
- Dirty flagA boolean that marks data as changed, so expensive recomputation happens only when something actually moved — not every…
- Dirty PipeCVE-2022-0847 — Linux kernel bug. Write to arbitrary files even when read-only (overlayfs, SUID binaries) via splice + pipe.
- Dirty readOne transaction sees changes another has made but not yet committed — if the other rolls back, you've read "phantom data".
- Dirty rectanglesA rendering optimization that redraws only the screen regions that actually changed, instead of the whole image every frame.
- Disappearing messageMessages that delete themselves automatically after a set time or after being read. Snapchat built its entire identity on…
- Discard ProtocolThe network's /dev/null: port 9 accepts everything and never says a word.
- Disco CorporationThe Japanese firm that saws and grinds nearly every wafer on Earth — and that almost no one outside the industry has heard…
- DiscordChat and voice platform launched in 2015 for gamers, now a general-purpose community platform with 200+ million monthly…
- Discord botA program that logs in as its own member of a Discord server. It's registered in the developer portal and invited with a URL…
- Discord forum channelA Discord channel type (2022) where each new post becomes its own thread with a title and tags, instead of a continuous chat…
- Discord serverDiscord's fundamental community unit. Internally: "guild" (gaming heritage). Contains channels (text + voice), roles…
- Discord StageDiscord channel type for live presentations with speaker/audience role split. Launched 2021 as a response to the Clubhouse…
- Discord threadSide-branch conversation inside a channel on Discord. Launched 2021, expanded 2022 with "Forum channels". Use: side-talk…
- DiscourseModern forum software — Atwood's (Stack Overflow co-founder) attempt to modernise the phpBB era.
- Discworld MUDTerry Pratchett's Discworld as a text game over telnet, running since 1991 with the author's blessing.
- Disk bufferThe small DRAM on a drive's board that decouples the mechanism from the bus — reading ahead, buffering writes and smoothing…
- Disk compressionTransparent compression of a whole disk volume to squeeze out more space — the 1990s answer to small, expensive hard drives.
- Disk magazineA magazine on a floppy disk, read on screen through a custom reader with a menu, chip music and scrolling text.
- Displacement mappingActually moving the surface points outward according to a height texture, so the detail has a real silhouette and shadows…
- DISPLAY (X11)The environment variable that tells every X program which screen to draw on, in the form host:display.screen.
- Display GhostscriptThe GNU project's free stand-in for Adobe's Display PostScript, built on Ghostscript, so that DPS programs could draw on…
- Display managerThe program that starts the X server or compositor, draws the login screen and hands the display over to a graphical session.
- Display PostScriptAdobe's system for drawing the screen in the same language printers spoke, so what you saw really was what you got.
- DisplayPort (DP)The modern standard for computer monitor connectors — high refresh rates, MST (multiple monitors from one cable).
- DispoPhoto-sharing app that mimics disposable cameras: take photo now, see it first the next morning. David Dobrik-related…
- Distance attenuationSound growing fainter the farther its source is from the listener — physically by the inverse-square law, in games by a…
- Distance jointA physics constraint that keeps two anchor points on rigid bodies a set distance apart — stiff like a rod or springy like…
- DistinguisherA procedure that tells a cipher's output apart from random data, and so breaks a property an ideal cipher should lack.
- Distinguishing attackAn attack that only has to show that a cipher behaves differently from a random function, not that it can be broken.
- Distracted BoyfriendThe stock photo of a man turning to look at a passing woman while his girlfriend looks appalled. Perhaps the purest example…
- Distributed tracingTrace a request through the entire distributed system — each service contributes a "span" to a shared "trace". Shows where…
- Distributed transactionTransaction that spans multiple DBs or services. Classic solution: 2PC (Two-Phase Commit) via XA protocol. Notoriously…
- Distribution (Usenet)A Usenet header asking servers to keep a post within a given area — a request the rest of the world often ignored.
- DistrolessContainer images without an OS distribution — just your app + runtime + necessary libs.
- Dither (audio)A faint, deliberate noise added before bit depth is reduced, so the rounding error becomes steady hiss instead of distortion…
- DitheringDeliberately adding noise to fool the eye into seeing more colours than are actually present.
- Divide and conquerAlgorithmic strategy: split the problem into smaller subproblems, solve them recursively, combine the results. "Divide and…
- Divider/square-rooter (ENIAC)One cabinet handled both division and square roots, and both by subtracting over and over until it ran out of room.
- Division propertyA generalisation of the integral attack's balance properties that tracks which algebraic degrees survive through a cipher's…
- DIX and DDXThe X server's split into a machine-independent core that speaks the protocol and a hardware-dependent layer that draws: the…
- DJIA Chinese company that turned the drone into a consumer product, then dominated the market so thoroughly that it became a…
- DKIMDomainKeys Identified Mail — a method where outgoing email is cryptographically signed with the domain's private key, so the…
- DLL sideloadingPlacing your own code in a file with the right name next to a signed and trusted binary, and letting that binary start it…
- DLPData Loss Prevention — technology and policies that detect and prevent sensitive data from leaving the organization…
- DLQ (Dead Letter Queue)A separate queue for messages that have failed too many times — for manual investigation instead of infinite retry.
- DLS (Downloadable Sounds)The MIDI industry's standard format for sampled instruments, letting a MIDI file bring its own sounds instead of trusting…
- DLSSNvidia's technique for rendering at lower resolution and letting a neural network scale it up — more frames with no visible…
- DLT (Digital Linear Tape)Half-inch tape format using linear serpentine recording that ruled server backup in the 1990s until LTO shoved it aside.
- DMA (Direct Memory Access)Peripherals reading and writing system memory on their own, without the processor copying every byte. Without DMA a modern…
- DMA engine (Direct Memory Access)A hardware component that lets peripherals (disks, network cards, GPUs) move data directly to and from RAM without going via…
- DMARCDNS-based rule saying "if mail from my domain doesn't pass SPF or DKIM — throw it away".
- dmenuA dynamic menu that reads lines from standard input, lets the user narrow them down from the keyboard and prints the choice.
- DMF (Distribution Media Format)Microsoft's floppy format that squeezed 1.68 MB onto an ordinary 1.44 MB diskette by writing more sectors per track.
- Dmitri AlperovitchRussian-born American security researcher who co-founded CrowdStrike and turned nation-state attribution into a business…
- Dmitry SklyarovRussian programmer arrested by the FBI after giving a conference talk on the weaknesses of Adobe's e-book protection.
- DMS (DiskMasher)Amiga format that packs a whole floppy into one file — boot block, custom tracks and all.
- DMZ (Demilitarized Zone)A "buffer zone" in the network where externally reachable services live — between the internet and the internal network.
- DNS (Domain Name System)The internet's phonebook — translates thern.io into an IP address like 185.97.7.85.
- DNS amplificationDDoS technique — send small DNS queries with a spoofed source to the victim's IP; the open resolver replies with LARGE…
- DNS over HTTPS (DoH)DNS queries sent encrypted over HTTPS — ISPs and WiFi snoopers can't see which sites you visit.
- DNS rebindingA page loads from attacker.com, but the attacker's DNS server returns different IPs at different times — first a public IP…
- DNS tunnelingA technique for smuggling data or C2 traffic through DNS queries — by encoding the information in subdomain names and…
- DNS64A resolver that lies helpfully: when a name has no AAAA record it invents one by embedding the IPv4 address inside an IPv6…
- DNSSECCryptographic signatures on DNS responses — proves the answer came from the right source and wasn't tampered with.
- do-notationHaskell syntactic sugar for chained bind calls. Make monadic code look imperative. do { x <- getName; y <- getAge; return…
- DockThe row of application icons along the screen edge that NeXTSTEP introduced in 1989 and macOS made famous — half launcher…
- DockappTiny X programs of 64 by 64 pixels, showing a clock, CPU load, network traffic or the weather, built to sit in Window…
- DockerThe most popular tool for building and running containers.
- Docker ComposeDefine + run multi-container apps in a YAML file. Originally "Fig" (Orchard Labs, 2013), Docker acquired 2014, renamed to…
- Docker SwarmDocker's built-in container orchestration. Launched 2014. Tried to be a Kubernetes alternative with "Docker simplicity"…
- Docker volumeMechanism for persistent storage in Docker containers. Three types: named volumes (Docker-managed), bind mounts (regular…
- DockerfileText file with instructions for building a Docker image.
- DOCSIS (Data Over Cable Service Interface Specification)The standard that lets cable-TV coax also deliver broadband.
- DocstringBuilt-in documentation inside code — Python """triple quotes""", JS JSDoc, Rust doc comments.
- DOCTYPEFirst line of an HTML file: <!DOCTYPE html> — tells the browser "this is HTML5, run in standards mode".
- DocusaurusA generator for documentation sites, built by Meta and released in 2017. It has become the default choice for open source…
- DocuSignThe company that made the print-sign-scan contract ritual obsolete — click, sign, done, and just as legally binding as ink.
- DogfoodingUsing the product you're building yourself — "eat your own dog food".
- DogpileMassive reaction against a specific post/person, often after a quote-tweet or cross-platform link. Thousands of replies…
- DoH (DNS over HTTPS)DNS over HTTPS — DNS queries via TLS-encrypted HTTPS instead of clear-text UDP 53. RFC 8484 (2018). Driven by privacy +…
- Dolby AtmosDolby's object-based surround format, which places sounds in three-dimensional space rather than in fixed speaker channels.
- Dolby Digital (AC-3)Dolby's lossy codec for 5.1 surround, which went from the cinema to every DVD player and AV receiver.
- Dolby noise reductionThe family of compander systems that tamed tape hiss — quiet treble is boosted on recording and pulled back down on…
- Dolby VisionProprietary HDR format (High Dynamic Range). 12-bit per channel (vs HDR10's 10-bit), dynamic metadata per scene/frame…
- Dollis HillThe Post Office research station in north-west London where a telephone engineer built the world's first programmable…
- DolphinDOSA German speed-up system for the Commodore 1541 that ran a parallel cable between computer and drive, making disk loading up…
- DoltMySQL-compatible database with Git semantics — branch, merge, diff, blame on table rows.
- DOM (Document Object Model)The tree of objects the browser builds from HTML — what JavaScript manipulates to change the page.
- DOMAIN (Postgres)PostgreSQL feature: create your own type with an embedded constraint. CREATE DOMAIN email AS TEXT CHECK (VALUE ~…
- Domain separationTagging each use of a cryptographic primitive with a unique label, so output from one context can never pass for output from…
- Domain warpingDistorting a noise function's input coordinates with another noise function, so flat gradients fold into swirling, organic…
- DomoCloud BI built by the man who sold Omniture to Adobe — dashboards for executives, priced to match.
- Don BuchlaCalifornian designer who built a modular synthesizer at the same time as Moog but refused to give it a piano keyboard.
- Don CoppersmithIBM cryptographer on the DES team whose 1994 account revealed that the designers knew about differential cryptanalysis in…
- Donald BeaverAmerican cryptographer whose 1991 "Beaver triples" are still the standard trick for multiplying secret values in multiparty…
- Donald KnuthHas been writing a book about algorithms since 1962 that is still not finished — and built an entire typesetting system in…
- Donald MichieThe Bletchley veteran who taught a stack of matchboxes to play noughts and crosses — and founded British machine learning.
- DongleA physical key you plugged in to let the program start — copy protection's hardware variant.
- Donn ParkerThe SRI researcher who was cataloguing computer crime before most people believed there was such a thing.
- DoomThe game that spread as shareware, invented deathmatch, and then became programmers' standard test of whether a thing can…
- DoomscrollingCompulsively continuing to scroll through grim and distressing news and posts, even though it makes you feel bad. A word…
- Door gameThe BBS game run through a "door" out of the system — turn-based, with a handful of moves a day against other members.
- DoorDashUS food-delivery leader — ~65 % US market share. Includes delivery of everything (groceries, liquor, flowers, Best Buy…
- DoP (DSD over PCM)A way of sneaking 1-bit DSD audio through drivers that only speak PCM, by dressing it up as PCM samples.
- Dope (demo)PC demo by the Finnish group Complex that won the demo competition at The Gathering 1995.
- DoQ (DNS over QUIC)DNS over QUIC — RFC 9250 (2022). DNS via encrypted QUIC transport, port 853. Faster than DoT (less handshake overhead)…
- Dorabella cipherA short note from the composer Edward Elgar in 1897, written in tiny semicircles, that nobody has managed to read since.
- Dorothy DenningThe researcher behind two of computer security's foundational models — and one of the few academics who publicly defended…
- Dorr FeltThe inventor who built the first practical key-driven calculator out of a macaroni box.
- DoTDNS over TLS — DNS via TLS-encrypted TCP, port 853. RFC 7858 (2016), older than DoH. Easier for enterprises to control (port…
- Dot flagA grid of dots rippling like a flag in the wind, often in the group's logo colours — a classic oldskool effect on the Amiga…
- Dot matrix printerAn impact printer that builds each character from tiny dots hammered through an inked ribbon by a column of pins.
- Dot morphingDemo effect in which a cloud of dots glides from one 3D shape to another — cube becomes sphere becomes the group logo.
- Dot tunnelA tunnel built from flying points instead of a textured surface — cheap enough for machines with no fill rate.
- Dota 2Valve's free-to-play MOBA from 2013, grown out of a Warcraft III mod and famous for The International and its record prize…
- DotfilesConfig files in the home directory starting with a dot: .bashrc, .vimrc, .gitconfig.
- Double bufferingDraw into an off-screen buffer and swap it in all at once, so the viewer never sees a half-drawn frame.
- Double density (DD)The floppy class that, using MFM encoding, packed twice what single-density FM did — 360 KB on 5.25" and 720 KB on 3.5".
- Double DESRunning DES twice sounded like a simple doubling, and it did not deliver the security people hoped for.
- Double encryptionEncrypting twice with two keys does not double the security, and people knew that already in 1977.
- Double patterningSplitting one layer across two masks so you can draw finer patterns than a single exposure at that wavelength allows. The…
- Double RatchetAlgorithm in the Signal Protocol that generates new encryption keys for every message. "Double" = combines a Diffie-Hellman…
- Double steppingA quirk in Enigma that let the middle rotor move two steps in a row, making rotor positions less random than they looked.
- Double taggingA VLAN-hopping technique where the attacker puts two 802.1Q tags on a frame. The first switch strips the outer (native-VLAN)…
- Double transpositionDouble transposition runs two rounds of columnar transposition with different keys, which makes it hard to break by hand.
- Double-spendingSpending the same digital "money" twice — the core problem cryptocurrencies solve with blockchain.
- Double-write bufferA MySQL/InnoDB mechanism that protects against "torn pages" — when a page is only partially written during a power failure…
- DoubleClickThe ad company that turned the third-party cookie into the web's tracking infrastructure, bought by Google in 2008.
- Doug TygarCo-author of Why Johnny Can't Encrypt — the study that showed secure software nobody can use isn't secure.
- Doug WhitingThe cryptographer in Schneier's circle who made money first by squeezing data and then by encrypting it.
- Douglas EngelbartDemonstrated the mouse, hypertext, video conferencing and real-time collaborative editing in 1968 — all in one sitting, nine…
- Douglas HartreeThe physicist who built Britain's first differential analyzer — partly out of Meccano.
- DoveNetThe message network linking BBSes that run Synchronet, with Rob Swindell's Vertrauen as its hub.
- DownmixFolding a multichannel mix into fewer channels, usually surround into stereo, without losing the dialogue along the way.
- DoxxingPublishing personal information about someone online — real name, address, phone number, workplace — without their consent…
- Doze modeAndroid's battery-saving state that shuts down apps' background work once the phone has been sitting still for a while.
- DPAPIThe Data Protection API is Windows' built-in way of encrypting secrets with keys tied to the user's logon or the machine.
- DPC latencyThe delay when a Windows driver spends too long on its deferred work and the audio driver has to wait its turn.
- DPDK (Data Plane Development Kit)A library that moves all packet processing out of the kernel and into the application. Started by Intel in 2010 to reach…
- DPI (Dots Per Inch)Resolution measure — dots per inch. Printers: 600–2400 DPI. Screens (more correctly PPI, Pixels Per Inch): 100 PPI (1080p…
- DPMSThe 1993 VESA standard that lets a graphics card tell the monitor it may go to sleep, and the X11 extension of the same name…
- DPO (Direct Preference Optimization)Simpler alternative to RLHF — train directly on preference pairs without a separate reward model.
- DPO (Direct Preference Optimization)A method (2023) for aligning an LLM to human preferences directly from pairs of "preferred/not-preferred" answers — without…
- DPU (Data Processing Unit)A small complete computer on the network card that takes over networking, storage and security from the host CPU — and can…
- Draft modelSmall LLM that generates candidate tokens; larger "target" LLM verifies in parallel. Powers speculative decoding. Acceptance…
- Dragon 32A Welsh home computer from 1982 with an unusually elegant processor and an unusually short life.
- DragonBonesA Chinese 2D skeletal animation tool and runtime, long the free alternative to Spine.
- Dragos RuiuCanadian conference organiser who turned vulnerability hunting into a spectator sport, then claimed to have found malware…
- DRAM (Dynamic RAM)The most common type of computer memory — cheap and dense, but must be "refreshed" thousands of times per second or it…
- DRAM refreshEvery bit in DRAM is charge on a minuscule capacitor that leaks. The whole memory therefore has to be read back and…
- Drama / Tea"Drama" = ongoing conflict/scandal in a community. "Tea" = gossip, often with "receipts" (screenshots as evidence). YouTube…
- DrataVanta's arch-rival in automated compliance — the same promise of continuous SOC 2 monitoring, founded two years later.
- Draw callA single command telling the GPU to render a batch of geometry — issue too many and the CPU, not the graphics card, becomes…
- Draw distanceThe distance from the camera beyond which geometry is no longer drawn — hidden behind fog or clipped away entirely.
- Drawable (X11)The X protocol's collective name for anything you can draw on: a window or a pixmap, treated identically by every drawing…
- DREADRisk rating model for security threats: Damage, Reproducibility, Exploitability, Affected users, Discoverability. Score 1-10…
- DreamHackA Swedish computer party that started in a school basement in Malung in 1994 and ended up as a global esports brand.
- DreamHostVeteran host from 1996 that happened to birth Ceph along the way.
- DremelGoogle's internal system for interactive ad hoc queries over trillions of rows, described in a 2010 paper. The engine behind…
- DremioA lakehouse query engine built on Apache Arrow by the people who created Arrow — SQL straight against the files in the data…
- DRI (Direct Rendering Infrastructure)The architecture that let X programs on Linux talk straight to the graphics card, bypassing the X server, without chaos…
- DRI2The second generation of direct rendering under X, which gave every window its own buffers and finally let 3D programs…
- DRI3Keith Packard's 2013 simplification: the client allocates its own graphics buffers and passes them to the X server as file…
- DrinkOrDie1990s warez group best remembered for two things: Windows 95 before the shops had it, and being the main target of Operation…
- DrivecodeCode that runs on the disk drive's own processor — the 1541 is a whole computer, and demos exploited it.
- DriverSoftware component that lets the OS talk to specific hardware. Translates between generic API calls ("read sector X") and…
- DrizzleLightweight TypeScript ORM that stays close to SQL — schema is a TS file, queries look like SQL, and no runtime magic blocks…
- Drizzle ORMSQL-first TypeScript ORM. Dimitri Dunin + Andrew Sherman, 2022. Typed query builder that looks like SQL. Edge-optimized…
- DRM (Digital Rights Management)Technology that restricts what you may do with content you have paid for.
- DrMOS / Integrated Power StageIntegrated power stage: high-side MOSFET + low-side MOSFET + gate driver in one package. Replacement for discrete MOSFETs on…
- DroboThe storage box with the row of lights that let anyone mix drive sizes without understanding RAID — until the company itself…
- Drop fileA small text file the BBS software wrote to disk just before handing the caller over to an external program.
- Drop-on-demandThe inkjet method that fires each droplet only at the instant it's needed — the opposite of a continuous stream.
- DropboxPioneer of cloud file sync — "drop a file in a folder and it's synced to all your devices". Y Combinator 2007.
- DropoutTraining technique: randomly turn off neurons on each training step — forces the network not to rely on individual neurons.
- DROWN attackDROWN decrypts modern TLS sessions by using an old SSLv2 service that shares the same RSA key.
- Drum machineAn electronic instrument that plays programmed drum patterns — first meant to replace drummers, later a genre in its own…
- Drum memoryA rotating metal cylinder with one read head per track — the main memory of the 1950s, where fetching a number took as long…
- Drum plotterA pen plotter that rolls the paper back and forth over a drum while the pen only moves sideways — drawing length limited…
- Drum printerA line printer built around a spinning drum where every print column carries the full character set.
- Drum scannerA high-resolution prepress scanner that mounts the original on a spinning cylinder and reads it with photomultiplier tubes.
- Drunkard's walkA level-carving method where a random-walking "digger" tunnels floor out of solid rock until enough is open — the lazy route…
- DRY (Don't Repeat Yourself)Principle: the same logic should exist in just one place in the code.
- DSCPDifferentiated Services Code Point — a 6-bit field in the IP header for QoS marking. Replaced the ToS field (RFC 2474)…
- DSD (Direct Stream Digital)Sony and Philips's audio format that stores a delta-sigma converter's 1-bit stream as is, rather than turning it into PCM.
- DSP loadHow much of each audio buffer period is spent computing the sound — and so how close you are to the next dropout.
- DSPyStanford framework that treats prompts as compilable code — you declare input/output signatures, provide examples, and DSPy…
- DSSIDisposable Soft Synth Interface — Linux's stopgap for software instruments, built on top of LADSPA and later replaced by LV2.
- dtactionCDE's action database and the command that runs an action by name — the layer that made a double-click, a panel button and a…
- dtappmgr (Application Manager)CDE's application launcher: a file manager window full of icons that are really actions, reassembled at every login from…
- dtbuilderCDE's Application Builder, where you assembled a Motif interface with the mouse and let a code generator write the C.
- dtcalcThe CDE calculator, a direct descendant of Rich Burridge's calctool from SunView, with scientific, financial and logical…
- dtcmCDE's calendar, a networked scheduler built on an RPC daemon that left an open door in every 1990s Unix workstation fleet.
- dtcreateCDE's Create Action, the form that let an ordinary user turn a command into an icon without learning the syntax of the…
- dtfileCDE's file manager, which showed directories as icons in Motif-grey windows and let you drag files to the panel, the trash…
- dthelp (CDE Help System)CDE's help system, where manuals were written in the SGML dialect HelpTag, compiled into volumes and shown in dthelpview…
- dticonCDE's icon editor: a grid of fat pixels, a palette made of the desktop's own colour roles, and the button that grabbed a…
- dtinfoCDE's Information Manager of 1997: an SGML-based reader for whole manuals with full-text search, bookmarks and annotations…
- dtkshCDE's desktop KornShell — an ordinary Unix shell with built-in commands for building Motif windows.
- dtloginCDE's login screen, a descendant of XDM that served both local users and X terminals over XDMCP.
- dtmailThe mail client of CDE, a Motif-dressed descendant of Sun's Mail Tool that read the mailbox straight off disk and handed…
- dtpadCDE's text editor — Motif grey, with a menu bar, spell checking and word wrap, meant for mail and README files rather than…
- dtprintinfoThe CDE Print Manager: a window with every lp printer as an icon and its queue as a list, onto which you dragged files to…
- dtscreenCDE's screen saver, essentially xlock's animations broken out into a program of their own that the session manager started…
- dtsessionCDE's session manager, which brings up the desktop after login and remembers which programs were open.
- dtspcdCDE's Subprocess Control Daemon, the service that launched programs for the desktop on other machines, and the hole through…
- dtstyleCDE's Style Manager — the window with buttons for colour, font, backdrop, mouse and focus that changed the whole desktop…
- dttermCDE's terminal window, built on Motif, and the default terminal on commercial Unix workstations through the 1990s.
- dtwmCDE's window manager — mwm plus workspaces and that wide front panel along the bottom of the screen.
- dtwmrcThe configuration file of CDE's window manager: .mwmrc with workspaces, a hook into the action database and a chain of…
- Dual actuatorA hard drive with two independent arm assemblies on one spindle, each able to seek over its own half of the platters, nearly…
- Dual channelA memory controller with two separate channels to the RAM modules instead of one. It doubles theoretical bandwidth — but…
- Dual contouringAn isosurface-extraction algorithm that, unlike marching cubes, places vertices inside the cells using surface normals and…
- Dual controlA principle where a sensitive operation requires two people, and neither of them can complete it alone.
- Dual licensingReleasing the same code under two licences: a copyleft licence that is free but infectious, and a commercial licence for…
- Dual playfieldThe Amiga's hardware trick of stacking two independently scrolling image layers — parallax without the CPU lifting a finger.
- Dual quaternion skinningBlend the bones' transforms as dual quaternions instead of matrices, and the joint stops collapsing when it twists.
- Dual_EC_DRBGThe random number generator that was slower and worse than the alternatives, became a standard anyway, and contained room…
- Dual-gridA tilemap technique where the visual grid is offset half a tile from the logic grid, so 16 tiles cover every transition…
- Duck typing"If it walks like a duck and quacks like a duck, it's a duck" — in dynamic languages it's enough for an object to have the…
- DuckDB"SQLite for analytics" — a columnar in-process OLAP database that runs as a library, not a server.
- DuckDB-WasmDuckDB compiled to WebAssembly — runs full analytics queries directly in the browser. Powers Observable, Hex, Mode notebooks.
- DuckDuckGoAmerican search engine whose entire business model is not knowing who you are.
- Duet (TikTok)A TikTok format where your video plays side by side with someone else's original in a split screen. Used to sing along…
- Dug SongThe hacker who first showed how trivially a network could be eavesdropped on, then built a billion-dollar company making…
- DUKPTA standard for deriving a unique key per transaction from a base key that only lives inside an HSM.
- Dungeon generationLetting code build dungeons and level layouts instead of hand-designing them — the roguelike's signature trick since Rogue…
- Duo SecurityThe company that turned two-factor login into a single tap on your phone.
- DuolingoGamified language-learning app — streaks, hearts, "the owl will get you". 100M+ MAU.
- Dupe checkThe check the release scene runs before putting a release out: has someone already released exactly this?
- Duplex printingPrinting on both sides of a sheet, either automatically with a flipping mechanism or manually in two passes.
- DVDThe optical disc that displaced VHS: 4.7 GB single layer, 8.5 GB dual layer.
- DVFS (Dynamic Voltage and Frequency Scaling)Power-management technique that adjusts a CPU/GPU's voltage and clock to match the load — saves battery and keeps…
- DVS (digital vinyl system)Records with no music on them: the groove carries a timecode signal that software reads to work out where the needle is and…
- DwitterA site for sharing visual JavaScript effects of at most 140 characters.
- dwmA tiling window manager in a couple of thousand lines of C, configured by editing the source and recompiling.
- DXC TechnologyIT services company formed in 2017 by merging two ageing outsourcing giants in the hope of making one healthy one.
- dxpcAn X protocol compressor from 1995 that put a proxy at each end of the modem line and sent only what differed from last time.
- DXVKA translation layer implementing Direct3D 9, 10 and 11 on top of Vulkan. Written by Philip Rebohle starting in 2018. One of…
- dxwmDECwindows' own window manager, built on the XUI toolkit and the one VMS and Ultrix users lived with until Motif took over.
- DYCPA C64 scroller in which every character sits at its own height, turning flat text into a rolling sine wave.
- Dye sublimationA printing method that vaporizes solid dye straight into the medium, giving continuous tone with no visible dots — hence…
- DYMOThe handheld embossing gun that punched raised letters into plastic tape — later a brand of label printers.
- DynThe DNS company half the American internet quietly depended on, as everyone learned the day its nameservers stopped…
- Dynamic ARP Inspection (DAI)A switch security feature that inspects ARP packets and drops those that don't match a known, legitimate IP-to-MAC binding…
- Dynamic batchingCombining many small moving meshes on the CPU every frame to cut draw calls — worthwhile only when they are tiny.
- Dynamic currency conversion (DCC)The "would you like to pay in your home currency?" prompt on a terminal abroad, to which the right answer is almost always…
- Dynamic difficulty adjustment (DDA)Lets a game read how the player is doing and quietly tune the challenge, keeping it balanced without a visible difficulty…
- Dynamic EQAn EQ band that only boosts or cuts when the signal in its frequency range crosses a threshold.
- Dynamic importLoading a JavaScript module at runtime with import("./module.js") as a function, instead of a static import at the top of…
- Dynamic microphoneA microphone whose diaphragm drives a coil through a magnetic field — a loudspeaker run in reverse.
- Dynamic programming (DP)Optimisation technique: solve recursive subproblems once and cache the results instead of recomputing. Richard Bellman…
- Dynamic rangeThe span between the loudest signal a system can handle and the quietest one still audible above its noise.
- Dynamic resolutionScales the render resolution up and down in real time according to GPU load, to keep the frame rate steady.
- Dynamic WindowsThe Symbolics window system in Genera 7, where everything ever printed to the screen remained a clickable object of known…
- DynamoDB StreamsAWS feature: DynamoDB exposes a change log (insert/modify/remove) as a stream. Use: event-driven architecture, trigger…
- DynatraceEnterprise APM + observability platform. Bernd Greifeneder + Austrian team, 2005. Single-agent (OneAgent) auto-instruments…
- DYPPThe more demanding sibling of DYCP: instead of each letter bobbing on its own, every pixel column gets its own height.
- LLM distillationSmall "student" model learns from large "teacher" model — either via output logits (classic Hinton distillation 2015) or by…
- Model distillationTrain a smaller, faster "student" model on the output of a large "teacher" model.
E
- AWS ECS (Elastic Container Service)AWS's home-grown container orchestrator — simpler than Kubernetes, deeply integrated with ALB, IAM, CloudWatch and Secrets…
- AWS EventBridgeManaged event bus from AWS — events from AWS services, SaaS partners (Stripe, Datadog, etc.) or your own sources are routed…
- E Ink (Electronic Paper Display, EPD)Microcapsules with black and white particles moved by electric fields — only draws power when the image changes. Weeks of…
- E-13BThe blocky number font along the bottom of a bank cheque, shaped so a magnetic reader recognises each character by its…
- E-core (Efficiency core)The small, energy-efficient core type in a heterogeneous chip — optimized for low power consumption and high throughput per…
- E-mu SystemsCalifornian company that made the sampler affordable for ordinary studios, and whose SP-1200 became the backbone of hip-hop.
- E-zineAn electronic magazine distributed as text files over BBSes and later the internet — the fanzine without the photocopier.
- E0The stream cipher protecting Bluetooth BR/EDR traffic, which cryptanalysts broke in theory long before the standard was…
- E2E test (End-to-end)A test that runs the whole app from the user's perspective — launches a browser, clicks, fills forms, checks the result.
- E2EE (End-to-End Encryption)Encryption where only the sender and receiver hold the keys — the server in the middle can't read anything.
- EAGLESpeculative decoding that guesses at the model's internal features rather than at the next token, which turns out to be…
- Eagle ComputerAn IBM PC cloner best remembered because its CEO died in his Ferrari the very day of the IPO.
- EANThe thirteen-digit barcode the rest of the world builds its shop goods on.
- EAP (Extensible Authentication Protocol)Framework for various authentication methods over 802.1X — enterprise Wi-Fi (WPA2-Enterprise), wired LAN.
- EAP-TLSThe most secure EAP method — mutual cert auth, no passwords. Typically required for regulated networks (government…
- Ear clippingA simple algorithm that triangulates a polygon by repeatedly clipping off "ears" — convex corners whose triangle is empty.
- Earl BoebertAmerican security researcher who, with Richard Kain, invented type enforcement, the model underneath SELinux.
- Early Hints (HTTP 103)A response the server sends before the real response, purely to say which files the browser can start fetching while the…
- Early reflectionsThe first sparse echoes off walls, floor and ceiling – the part that tells your ear how big the room is before the actual…
- Early-ZThe GPU runs the depth test before the pixel shader instead of after, so occluded fragments are discarded without ever…
- EARNBITNET's European branch, which gave Europe's universities email and mailing lists long before the internet arrived.
- EarthLinkThe American ISP that sold plain internet to people who didn't want AOL's walled garden.
- EarthlyBuild automation combining Dockerfile + Makefile concepts. Earthfile syntax: build: FROM golang ... RUN go build. Vlad…
- EasingA function that shapes the pace of an animation — slow-in, slow-out, overshoot — instead of a mechanical constant speed.
- EasyFlashA rewritable C64 cartridge with a megabyte of flash that turned disk games into instant-loading carts.
- EAX modeAn authenticated encryption mode that combines CTR with CMAC, presented in 2003 by Bellare, Rogaway and Wagner.
- EazelThe dot-com that in 1999 put Macintosh veterans to work on GNOME's file manager and ran out of money two months after…
- eBayThe original consumer-to-consumer auction site — started as "AuctionWeb" in 1995, $5 items sold and the whole e-commerce era…
- eBPFRun safe mini-programs in the Linux kernel without writing a kernel module — for observability, networking, security.
- eBPF securityUsing eBPF for security monitoring + enforcement. Tetragon, Falco, Cilium network-policy, BPF-LSM. Modern alternative to…
- eBPF toolsEcosystem of tools built on eBPF (extended Berkeley Packet Filter): bcc (Python-based), bpftrace (high-level DSL), Pixie…
- EBU R 128The European Broadcasting Union's 2010 recommendation that normalises broadcast audio to −23 LUFS instead of to peak level.
- EC2 (Elastic Compute Cloud)AWS's virtual servers — boot up and pay per hour/second.
- ECBEncrypt each block on its own. The result is a picture of a penguin that still looks like a penguin.
- ECB cut-and-pasteAn attack that moves and swaps blocks in an ECB-encrypted message without knowing the key.
- ECB penguinLinux's mascot, encrypted with AES in ECB mode and still easy to recognise.
- ECC memory (Error-Correcting Code)RAM with extra bits to detect and correct memory errors — standard in servers.
- ECC scrubbingA background process in ECC memory systems that periodically reads through all RAM, detects and corrects single-bit errors…
- ECC vs non-ECC RAMECC (Error-Correcting Code) RAM detects + corrects single-bit errors, detects 2-bit. Non-ECC accepts bit flips silently…
- Eccles-Jordan triggerTwo tubes wired so each holds the other down — the 1919 circuit that became the smallest home of the electronic bit.
- ECDSA (Elliptic Curve DSA)Digital signature based on elliptic curves — smaller keys than RSA, same security.
- ECHO (East Coast Hang Out)New York's answer to The WELL: a dial-up conferencing system Stacy Horn launched in 1990, known for having an unusually…
- Echo chamber (studio)A hard, empty room containing one loudspeaker and one microphone, built for no purpose other than adding reverb to…
- Echo ProtocolThe simplest service on the network: whatever you send to port 7 comes straight back.
- EchomailFidoNet's public conferencing system — shared topic threads copied from node to node overnight, roughly Usenet's newsgroups…
- Eckert-Mauchly Computer CorporationThe world's first computer company built two of history's most important machines and went under by quoting them at a fixed…
- ECMAScript (ES)The official standard JavaScript follows.
- ECMPEqual-Cost Multi-Path — when several paths to the same destination have the same cost, the router spreads traffic across all…
- ECNExplicit Congestion Notification — routers mark IP packets at incipient congestion instead of dropping them. Endpoints (TCP)…
- EcosiaA Berlin search engine that spends its ad profits on planting trees and has made itself impossible to sell.
- Ed FeltenThe Princeton professor who broke the music industry's watermarks and was then threatened with a lawsuit for explaining how.
- Ed SkoudisAmerican security instructor who trained a generation of incident handlers and pen testers — and turned attack techniques…
- Ed25519Fast deterministic signature scheme based on the Edwards curve Curve25519 — 32-byte public keys, 64-byte signatures, brutal…
- EDE (Equinox Desktop Environment)A small desktop environment from 2000 built on FLTK, with a panel and start menu that look like Windows 9x and that boots on…
- Edgar Allan PoePoe claimed in 1841 that any cipher could be solved, then wrote a story in which a cipher falls to frequency analysis.
- Edge AIRun ML inference on the device (phone, IoT, car) instead of in the cloud.
- Edge collapseThe atomic operation of mesh simplification: an edge is contracted to a single vertex and two triangles vanish.
- Edge flippingSwitching virtual desktop by pushing the mouse pointer against the edge of the screen: convenient for those who know about…
- Edge of DisgraceThe 2008 C64 demo that showed a 25-year-old machine could still surprise people who thought they had seen everything.
- Edge renderingRendering/running server code on the CDN's "edge" nodes geographically close to the user, instead of in a central data…
- Edge resistanceThe window manager feature that makes a dragged window pause for a few pixels at the screen edge or against another window…
- Edge-notched cardThe database before the computer: cards with a row of holes along the edge, a needle through the deck — and the cards…
- EdgecastA Southern California CDN that changed hands more often than most people change routers.
- EdgeDB (now Gel)Schema-first database on top of Postgres — its own query language EdgeQL / GelQL that replaces SQL.
- EdgioThe merger of two CDN challengers that was meant to create a strong number three and produced a bankruptcy within two years.
- editresX11R5's tool and protocol for looking inside a running Xt program's widget tree and changing its resources while it runs.
- EDREndpoint Detection and Response — security software on computers and servers (endpoints) that continuously monitors…
- EDS (Electronic Data Systems)The company that invented IT outsourcing — someone else runs your computers for you — and turned its founder into a…
- EDSACThe Cambridge machine that first did real work for real users — and invented the subroutine along the way.
- Edsger DijkstraThe Dutchman who turned programming into a mathematical discipline — and who said so with a sharpness that made him both…
- EDVACThe machine that lent its name to the report defining the modern computer — and then took six years to switch on.
- Edward HebernAmerican inventor (1869–1952) who built one of the first electric rotor machines — and watched others make the money from it.
- Edward KleinschmidtGerman-American inventor whose teleprinter became the foundation of the Teletype Corporation.
- Edward SnowdenThe whistleblower whose 2013 leaks made encryption the default rather than the exception.
- EEPROM (Electrically Erasable Programmable ROM)Programmable non-volatile memory — can be written and erased electrically, byte by byte.
- EFAILA 2018 family of attacks that tricked email clients into leaking the plaintext of encrypted OpenPGP and S/MIME messages…
- Effect commandThe little hex code at the right edge of a tracker cell that makes a static sample slide, wobble or fall silent.
- Effects pedalA small box on the floor with a footswitch, an input and an output — the form factor guitar effects have lived in since the…
- EFL (Enlightenment Foundation Libraries)The library stack the Enlightenment project built during its twelve-year road to E17, its own canvas, main loop, theme…
- EFM (eight-to-fourteen modulation)The channel code on a CD that maps each data byte to 14 channel bits, keeping the pits a length the laser can actually read.
- EFnet (Eris Free Network)The original large IRC network, formed in 1990 when the majority of servers disconnected eris.berkeley.edu, which let anyone…
- EggdropThe world's oldest IRC bot still maintained, written by Robey Pointer in 1993. It sits in the channel around the clock and…
- eGPU (External graphics card)A desktop graphics card in an external enclosure, connected to a laptop over Thunderbolt or OCuLink. Gives thin machines…
- Ehud TenenbaumIsraeli hacker known as The Analyzer, whose 1998 break-ins to US military systems were first suspected to be an Iraqi attack.
- EIESThe Electronic Information Exchange System at NJIT, where computer conferencing was studied as a social phenomenon before it…
- EIGRPEnhanced Interior Gateway Routing Protocol — Cisco's internal routing protocol. Proprietary 1992-2013, opened as RFC 7868…
- El AjedrecistaA 1912 machine that played the king-and-rook versus lone-king endgame — not elegantly, but always to mate.
- El ToritoThe 1994 spec that made CDs bootable by pretending, to the BIOS, to be a floppy or a hard disk.
- Elaine BarkerThe NIST cryptographer behind the key management and random number generation standards — including the one that contained…
- ElasticThe company behind Elasticsearch, best known outside its niche for a licence change that ended in a fork.
- ElasticsearchDistributed search engine built on Apache Lucene — Shay Banon, 2010 (Elastic NV). RESTful API, JSON documents…
- élastiqueBerlin-based zplane's licensed time-stretching and pitch-shifting engine — the thing actually doing the work when you drag…
- ElectricSQLLocal-first sync between client SQLite/PGlite and central PostgreSQL — build apps that work offline but sync magically…
- Electromagnetic analysisMeasures the electromagnetic leakage from a circuit instead of its power draw, and can aim the measurement at one small…
- Electromechanical relayAn electrically operated switch — a coil pulls an armature that opens or closes contacts — and the first technology fast and…
- ElectronBuild desktop apps with web tech (HTML/CSS/JS). Packages Chromium + Node.js runtime. Cheng Zhao, GitHub, 2013 (originally…
- Electronic ArtsThe publisher that began by treating developers like rock stars and ended up as the industry's favourite villain.
- Electronic brainThe 1940s newspaper word for a computer — loathed by the people who built them, loved by everyone else, and back almost…
- Electronic Frontier FoundationThe non-profit founded in 1990 to defend civil liberties online, with the hacker raids of that year as the immediate trigger.
- Electrostatic printerA printer that lays a charge pattern onto coated paper with a fixed row of tiny electrodes and pulls toner to it — fast…
- ElektronThe Gothenburg company whose drum machines and samplers are built around a sequencer in which every step can carry its own…
- ElementThe leading client for the Matrix protocol. It was called Vector, then Riot.im, and switched to Element in 2020 to shed the…
- ElementInternalsThe API that lets a custom element behave like a real built-in element rather than a div in disguise.
- Elephant diffuserBitLocker's original add-on to AES-CBC, stirring each sector so that a single flipped bit garbled the whole thing.
- Elephant flowA traffic flow of large volume and long duration — datacenter replication, video upload, backup. Opposite: mice flows (RPC…
- ElevatedA 2009 4k intro with snowy mountain landscapes, still the go-to exhibit for how far 4096 bytes can stretch.
- Elevator (OPEN LOOK)The OPEN LOOK scrollbar, in which the arrows and the grip were joined in a small elevator that rode along a cable: a design…
- ElevenLabsPolish-founded AI company — the best text-to-speech quality on the market, can clone a voice from a 1-minute sample.
- Eleventy (11ty)A static site generator in JavaScript, started by Zach Leatherman in 2018. It ships zero client-side JavaScript by default…
- ELF (Executable and Linkable Format)Standard binary format for Linux, BSD, Solaris, mobile OSes. Replaced a.out + COFF in Unix. Supports executable files…
- ElGamalDiffie-Hellman upgraded from key exchange to full encryption — at the price of doubling the ciphertext.
- ElgatoA German hardware maker whose capture cards and Stream Deck button box became standard kit on every streamer's desk.
- Eli Ben-SassonTechnion researcher who carried probabilistically checkable proofs out of complexity theory's back rooms and into…
- Eli BihamShamir's doctoral student who co-invented differential cryptanalysis — and then spent a career applying it to everything.
- Elias Levy (Aleph One)Author of the text that taught a whole generation how to exploit buffer overflows.
- Elie BurszteinFrench researcher at Google with a habit of proving that security mechanisms merely look secure.
- Elite accessThe top permission tier on a BBS, where the newest files and the hidden areas lived — and the origin of the word ”leet”.
- ElixirFunctional language on the BEAM (Erlang's VM) — José Valim, 2011. Modern syntax + macros, all of OTP's concurrency and fault…
- ELIZAThe first chatbot, written by Joseph Weizenbaum at MIT in 1964–1966. The famous DOCTOR script imitates a Rogerian therapist…
- Elizabeth FeinlerThe chemist who ran ARPANET's information centre for seventeen years and whose group gave the internet .com, .edu and .gov.
- Elizebeth FriedmanThe codebreaker who took down rum-runners and Nazi spy rings, and whose work J. Edgar Hoover was happy to take credit for.
- ElkA modern, fast web client for Mastodon built in Vue/Nuxt by members of the Vue/Vite community. Popular for its polished…
- EllemtelThe joint R&D company of Ericsson and the Swedish telecom administration, where the AXE switch and later Erlang took shape.
- Elliott BrothersA London instrument maker from the Napoleonic era that became one of Britain's first computer manufacturers in the 1950s.
- Elliptic-curve cryptographyPublic-key cryptography built on points on a curve rather than large primes — the same security at a tenth of the key length.
- Elm (mail client)One of the first full-screen email clients on Unix, written at HP in 1986 and the default at many universities until Pine…
- Elonka DuninAmerican game developer and amateur cryptologist who became the hub for work on Kryptos and other unsolved ciphers.
- Elpida MemoryJapan's last homegrown DRAM maker — named after the Greek word for hope, which reads like foreshadowing in hindsight.
- ELXSIA 64-bit minisupercomputer built around a fast message bus — and Gene Amdahl's refuge when the wafer dream collapsed.
- ElysiaJSBun-native web framework. SaltyAom, 2022. ~200k req/sec (fastest JS framework). Type-safety via TypeScript inference…
- eMachinesThe brand that pushed PC prices below $500 and turned the home computer into something you picked up next to the microwaves.
- EmacsA fully extensible editor — at its core a Lisp interpreter that happens to display text. GNU Emacs (Richard Stallman, 1985)…
- EmailThe internet's oldest surviving application. Ray Tomlinson sent the first one in 1971 between two ARPANET computers. He…
- Embarcadero TechnologiesThe company that now owns Delphi and C++Builder, picked up in Borland's closing-down sale.
- Embark StudiosThe Stockholm studio where DICE veterans tried to make game development cheaper with procedural generation and machine…
- Embedded servoPositioning information woven into short servo zones between the data sectors, so the head can correct its position many…
- EmbeddingA word, sentence or image translated into a list of numbers that captures its meaning.
- Embedding driftThe problem that embeddings from different models (or model versions) aren't comparable — so when you switch or update the…
- Embedding modelA model that converts text (words, sentences, documents) into a vector of numbers that captures its meaning, so semantically…
- Ember.jsConvention-over-configuration JS framework — "Ruby on Rails for frontend". Yehuda Katz + Tom Dale, 2011. Used by LinkedIn…
- EMCThe Massachusetts storage giant that sold expensive disk cabinets to banks, owned VMware and was swallowed by Dell in what…
- EME modeA wide-block mode built on ECB with a mixing layer in between, so that a change in one block spreads across the whole block.
- EmeraldBeryl's window decorator from 2006, the program that drew title bars and frames with its own theme engine, and the only part…
- EMIB (Embedded Multi-die Interconnect Bridge)A small silicon bridge buried in the package substrate connecting two adjacent dies, instead of laying an entire silicon…
- Emil PostThe logician who formulated computability independently of Turing, in the same year, and ended up as the first half of…
- Emily PostnewsBrad Templeton's 1980s satirical advice column that taught Usenet etiquette by recommending exactly the wrong thing with…
- eMMC (embedded MultiMediaCard)"SD card on the motherboard" — cheap flash storage for budget phones, Chromebooks, IoT devices.
- EmojiPictographs encoded in Unicode — each emoji is one (or more) "code points".
- Emoji reactionMark a reaction to a message with an emoji instead of writing a new message. Slack popularized it in chat context (2014)…
- EmoteA small image typed into chat by a text name. It differs from an emoji by not being standardized — an emote is the…
- EmoticonA face made of punctuation and read with your head tilted — the smallest and most widespread form of ASCII art.
- EmotionCSS-in-JS library from 2017 by Kye Hohenberger. Offers both the styled.div API popularized by styled-components and a looser…
- EMS VCS3The small 1969 British synth where you connected modules by pushing pins into a grid instead of running patch cables.
- EMSIThe handshake that let two FidoNet mailers introduce themselves, agree on protocols and show passwords in a single packet…
- Emulate3ButtonsThe setting that gave a two-button mouse a pretend middle button, triggered by pressing both at once.
- EmulatorSoftware that imitates another computer's hardware closely enough that the original programs cannot tell the difference.
- EmulexCalifornian maker of Fibre Channel adapters for storage networks, once famous for losing half its market value to a fake…
- EMVThe global chip-card standard, in which the card computes a unique cryptogram for every purchase instead of reciting the…
- EncapsulationOOP principle: hide internal details behind a simple interface.
- Encore ComputerThe Multimax shared-memory multiprocessor, built by an all-star cast of DEC and Data General defectors.
- Encrypt-and-MACThe ordering where the plaintext is encrypted and MACed separately, with the tag sent alongside the ciphertext.
- Encrypt-then-MACThe ordering that decides whether encryption and integrity protection actually add up.
- Encrypted Key Exchange (EKE)The first password-authenticated key exchange (PAKE), where a weak password is enough because it can't be cracked offline.
- EncryptionScrambling data so only someone with the right key can read it.
- EndiannessThe order bytes are stored in memory for multi-byte values. Little-endian: least significant byte first. Big-endian: most…
- EndpartA demo's closing section — a long scrolltext of greetings, credits and scene gossip over the music.
- EneaOne of Sweden's oldest software houses, best known for the real-time operating system that quietly ran inside much of the…
- Engagement baitContent designed solely to elicit interactions (likes, comments, shares) in order to trick the algorithm into spreading it…
- Engagement rateMetric for creator influence: (likes + comments + shares) / followers per post, usually %. Standard ~1-3% for normal…
- Engine YardSan Francisco company that, during the Rails boom, was where you deployed your Ruby app if you didn't want to babysit…
- Engineering Research AssociatesA codebreaking team that moved into a disused glider factory in 1946 and became the country's leading memory manufacturer.
- English ElectricA British industrial giant that built locomotives, jet aircraft and some of the country's most important early computers…
- ENIACThirty tons of electronics built to compute ballistics tables — and programmed by moving cables around by hand.
- ENIAC programmersSix women were handed a machine with no manual and invented the job of programmer on the way.
- EnigmaThe German rotor machine whose single design flaw — that no letter could ever encrypt to itself — is what eventually brought…
- Enigma (demo)Swedish group Phenomena's 1991 Amiga demo, remembered as much for its soundtrack as for its filled vectors.
- Enigma M4The four-rotor Enigma variant used by U-boats, which gave Bletchley Park its hardest stretch.
- EnlightenReal-time indirect lighting middleware that let bounced light change as the sun set or a wall collapsed — without rebaking…
- EnlightenmentThe window manager that proved Linux could look good — and whose next version took twelve years.
- EnsembleCombine multiple ML models for better results than any single one.
- EnsoniqThe audio company founded by the man behind the Commodore 64's SID chip.
- EntegrisThe company that supplies the cleanliness rather than the machines — the filters, canisters and chemistry that keep a fab…
- EnterpriseDBThe largest commercial PostgreSQL company, built on the promise that you can leave Oracle without rewriting everything.
- Entity Component SystemAn architecture where objects are bare IDs, data lives in components, and all logic sits in systems that sweep over those…
- Entity Framework (EF)Microsoft's original .NET ORM. Launched 2008 as part of .NET Framework 3.5. Three design models: Database First, Model…
- Entity Framework Core (EF Core)Microsoft's ORM for .NET — modern rewrite of the old Entity Framework. Cross-platform, supports SQL Server, PostgreSQL…
- Entity interpolationThe client draws other players' entities slightly in the past and interpolates between the two most recent server snapshots…
- EntropyA measure of unpredictability in bits — how many guesses an attacker needs on average.
- EntrustPKI company spun out of Nortel that spent thirty years as a certificate authority browsers trusted, until Chrome stopped.
- EntscheidungsproblemThe question of whether some mechanical procedure can decide which mathematical statements follow from the axioms — and the…
- EnTTA header-only modern C++ library implementing an entity component system on sparse sets rather than archetypes.
- Enum (Enumeration)A type that can only hold one of a fixed set of named values: Status = OPEN | CLOSED | PENDING.
- ENUM typeSQL type for fixed value lists: CREATE TYPE status AS ENUM ('active','pending','closed'). Type safety + storage-efficient…
- Enumeration attackList valid usernames, emails or other resources via systematic probing.
- Envelope encryptionData is encrypted with a random data key, and the data key is in turn encrypted with a master key that stays inside an HSM…
- Envelope followerA circuit or algorithm that turns an audio signal into a slow-moving curve of how loud it is right now.
- Environment mappingA trick for faking mirror-like surfaces by looking up a precomputed image of the surroundings instead of ray-tracing the…
- Environment variableKey-value pair available to processes — $PATH, $HOME, $DATABASE_URL.
- EnvoyHigh-performance L7 proxy. Matt Klein, Lyft, 2016. CNCF Graduated 2018. Default data plane in service meshes (Istio, Consul…
- Eoghan CaseyResearcher and investigator who turned digital evidence into an academic discipline with a methodology, not just a pile of…
- EPA (Expanding Polytope Algorithm)The algorithm that picks up where GJK stops and works out how deeply two bodies have interpenetrated, and in which direction.
- EPaxos (Egalitarian Paxos)A consensus protocol with no leader, where any node may propose directly and the ordering between operations is only pinned…
- Ephemeral containerA temporary container injected into an already-running pod for debugging, without restarting it. The solution to debugging a…
- Ephemeral keyA key generated for a single session and discarded afterwards, and the basis of forward secrecy.
- Ephemeral messageMessages that delete automatically after a timer — 5 seconds, 1 day, 1 week. Snapchat started the category (2011). Signal…
- Ephemeral portThe temporary source port the operating system hands out to an outgoing connection. The server listens on a well-known port…
- Epic GamesThe studio behind Unreal Engine and Fortnite, which has spent its money picking fights with app-store fees.
- EPLEltron's command language for label printers — older and simpler than ZPL, but still common in desktop models.
- EpochOne full pass through the entire training dataset during ML training.
- epollLinux's mechanism for watching thousands of connections from one thread — the foundation under nginx, Node and every modern…
- EPRMLExtended PRML — a read channel that stretches PRML with a longer target polynomial to cope with tighter packing.
- EpsonThe printer maker that began as a watch factory — the name literally means "son of EP", the printer that started it all.
- Epson MX-80Epson's 9-pin dot-matrix printer from 1980 that became one of the best-selling printers in the world and made Epson a…
- EPYCAMD's server CPU — up to 192 cores per socket, has eaten Intel's data center market.
- Epyx Fast LoadThe cartridge that made the C64's painfully slow disk drive bearable to live with.
- Equal temperamentThe tuning that splits the octave into twelve exactly equal semitones — and that MIDI, nearly every synth and every DAW take…
- Equal-loudness contourCurves showing how loud a tone must be at each frequency to sound equally loud — the ear is nowhere near linear.
- Equalizer (EQ)A bank of filters that boosts or cuts chosen frequency ranges — the most used tool in mixing, and the most overused.
- EqualLogicThe iSCSI storage whose scale-out peer architecture became Dell's first big storage acquisition in 2008.
- EquatoriumAn instrument that found the planets' positions from the Ptolemaic model by being turned to the right setting — no…
- Equifax breach 2017Massive data breach: 143-147 million Americans' SSN, credit cards, driver's license numbers stolen May-July 2017. Discovered…
- EquinixThe landlord of the internet's engine rooms: carrier-neutral data centres where networks meet to plug into each other.
- Equivalent keysDifferent keys that produce exactly the same cipher — quietly shrinking the key space, and ruinous when the cipher is used…
- Eran TromerIsraeli cryptographer who has listened RSA keys out of a laptop's noise and helped discover Spectre.
- Erase headA separate head first in the tape path that wipes the old content before the record head lays down the new.
- ERC-20The standard interface for fungible tokens on Ethereum — six functions that suddenly let every wallet handle any token.
- Eric ButlerThe developer behind Firesheep, the add-on that shamed the web into no longer sending login cookies in cleartext.
- Eric ChienTechnical director at Symantec Security Response who led the analysis of Stuxnet and its relative Duqu.
- Eric CorleyBetter known as Emmanuel Goldstein — founder of 2600: The Hacker Quarterly and the hacker scene's most persistent spokesman…
- Eric HughesThe mathematician who wrote the cypherpunk manifesto and boiled it down to three words: cypherpunks write code.
- Eric RescorlaThe man whose name stands alone on RFC 8446 — the specification for TLS 1.3.
- Eric YoungThe Australian whose side project SSLeay became OpenSSL — and with it the encryption under a large share of the web.
- EricssonThe Swedish telecom firm most people remember for old mobile phones, though its real business is the network: the switches…
- Erik TewsGerman researcher who took WEP cracking from hours to under a minute, then went after its replacement.
- ErlangFunctional language for fault-tolerant distributed systems — Joe Armstrong et al. at Ericsson, 1986, to run telephone…
- Ernest BrickellCryptographer who helped bury knapsack cryptosystems in the 1980s, then two decades later gave the TPM a way to vouch for…
- Error boundaryReact pattern: a class component that catches JavaScript errors in its subtree and shows fallback UI instead of crashing the…
- Error budgetThe gap between your SLO (say 99.9%) and 100% — how much downtime you "get" without breaking the promise.
- Error propagationHow much damage one flipped bit does to the ciphertext depends entirely on the mode of operation.
- ES modules in the browserThe browser's built-in support for JavaScript modules via <script type="module"> and import/export. It lets you write…
- eSATAExternal SATA — SATA interface designed for external disks. 6 Gb/s (same as internal SATA3). Launched 2004, peak adoption…
- esbuildJavaScript/TypeScript bundler written in Go. 10–100× faster than Webpack. Evan Wallace (Figma CTO), 2020. Base for Vite…
- ESC/PEpson's control-code language for dot-matrix printers, every command led by the ESC character — an industry standard for two…
- ESC/POSEpson's command dialect for receipt printers — the de facto standard every point-of-sale system speaks to a thermal printer.
- EscomThe German PC chain that bought what was left of Commodore in 1995 and went bankrupt itself the following year.
- ESD (Enlightened Sound Daemon)The 1998 sound server that let several programs make noise at once on a Linux whose sound card tolerated one opener at a…
- ESDI (Enhanced Small Disk Interface)A faster successor to ST-506 that moved the encoding onto the drive and added a proper command set.
- ESETSlovak antivirus company from Bratislava, best known for NOD32 and for researchers who keep finding state-built attack tools…
- eSIMEmbedded SIM — a programmable SIM chip soldered directly on the motherboard. Carrier profile is downloaded remotely, no…
- ESLintThe standard linter for JavaScript and TypeScript — catches bugs and style violations before the code runs.
- ESM (ES Modules)The official module system in JavaScript — import and export.
- ESM (ES Modules)Native JS module system. import / export syntax. Standardized ES2015 (ES6). Browser support 2018, Node.js stable support…
- ESP32Cheap MCU with built-in Wi-Fi and Bluetooth — IoT hobbyists' favourite, ~$3 per chip.
- Esperanto TechnologiesThe RISC-V shop's bid to run AI inference on over a thousand tiny cores instead of one big GPU.
- EsportsOrganised competitive gaming with teams, leagues, coaches and prize pools that occasionally exceed those of major sports…
- EspressifThe Shanghai company whose ESP8266 and ESP32 turned wireless IoT into a cheap hobby.
- EsriThe company behind ArcGIS and the shapefile, and therefore behind a good share of the world's map data.
- Essays on AutomaticsLeonardo Torres Quevedo's 1914 paper, which sketched an electromechanical analytical engine with floating-point arithmetic…
- ESSIVA way of deriving unpredictable initialization vectors for disk encryption from the sector number and a hash of the key.
- ETagAn HTTP header with a "fingerprint" of the response. The client sends it back in If-None-Match next time — the server…
- ETAOIN SHRDLUThe twelve most common letters in English, in the order they sat on a Linotype keyboard.
- etcdDistributed key-value store via Raft consensus. CoreOS, 2013. Go. Powers Kubernetes's control plane (all cluster state…
- EtchedBets the entire company on a single chip that burns the transformer architecture straight into silicon.
- Eternal SeptemberSeptember 1993, when AOL opened Usenet to its subscribers and the influx of new users never stopped. The term was coined by…
- EtherChannelBundling several physical switch links into one logical link ("port channel") for more bandwidth and redundancy. Cisco's…
- EthereumBlockchain with a built-in "world computer" — smart contracts via the Ethereum Virtual Machine. Vitalik Buterin, white paper…
- EthernetThe dominant standard for wired networks — the RJ45 sockets in your router.
- ETL (Extract, Transform, Load)The process that pulls data out of source systems, reshapes it and loads it into a data warehouse.
- ÉtoiléA desktop project on GNUstep, started in 2004, that wanted to replace applications and files with documents and components…
- EtsyBrooklyn startup that became the global handmade marketplace — has drifted toward "more Amazon-like" and lost some of its…
- ETW patchingOverwriting the function in your own process that ships trace events to Windows, so the process stops reporting on itself…
- EuConEuphonix's Ethernet-based control-surface protocol, inherited by Avid and made the backbone of its consoles.
- EudoraThe email client that let ordinary Mac and PC users pull their mail down to their own machine instead of logging in to a…
- Eugene KasperskyRussian virus hunter whose antivirus company exposed some of the most sophisticated state spyware ever found — and ended up…
- Euler anglesAn orientation described as three successive rotations about three axes — often yaw, pitch and roll.
- Euler integrationThe simplest way to step a simulation forward: add velocity times the timestep to position, one step at a time.
- EUnetThe European Unix network that carried email and Usenet across the continent long before commercial internet arrived there.
- EuphoriaNaturalMotion's animation engine, which makes game characters try to keep their balance instead of just collapsing like…
- EURion constellationThe pattern of five small rings on banknotes that makes copiers and image editors refuse to cooperate.
- EurorackThe dominant form factor for modular synthesizers: 3U-high modules, measured in HP, wired together with patch cables.
- EUV lithographyPrinting circuit patterns with light at a wavelength of 13.5 nanometres. The Dutch company ASML is the only maker of the…
- Eva GalperinEFF's director of cybersecurity, who got the antivirus industry to start treating stalkerware as the malware it is.
- Eval harnessA standardized framework for running a language model against a set of benchmarks and measuring its performance…
- Evals (LLM evaluations)Tests for LLM systems — automated quality metrics on prompts, models and agentic flows.
- Evans & SutherlandThe first proper computer graphics company, founded by two Utah professors who were building flight simulators while most of…
- Even–Mansour constructionThe smallest block cipher anyone could take seriously: a public permutation sandwiched between two XORs with key material.
- EventSomething that "happens" the code wants to react to — click, keypress, network response, timer tick, message arrives…
- Event busCentralised mediator where components publish events and others subscribe — without knowing about each other. Pub-sub inside…
- Event loopThe mechanism that makes JavaScript single-threaded yet async — runs one thing at a time, checks the queue between…
- Event mask (X11)The bitmask each X client sets per window to say which events the server should send — keys, mouse buttons, exposure…
- Event queueA queue where parts of a game leave messages for each other, so the sender never has to wait for the receiver to get round…
- Event sourcingA pattern where you store all changes as an immutable sequence of events instead of just saving the current state. The…
- Event-driven architectureArchitecture where components react to "events" instead of calling each other directly.
- EventideAmerican company that built some of the first digital audio effects and gave the industry the word "harmonizer".
- EventStoreDBDatabase purpose-built for Event Sourcing + CQRS — immutable, append-only event streams. Greg Young created it 2012.
- Eventual consistency"If no new writes are made, all replicas will eventually see the same value." Fast under partition, but can return stale…
- Eventual consistency (DB)The weakest common consistency guarantee: if no new writes happen, all replicas will eventually converge to the same value…
- EvernoteThe note-taking service with the elephant logo that taught a generation to save everything in the cloud — and then taught…
- Everything2Collaborative encyclopedia from 1999 that took the opposite path to Wikipedia: several personal pieces about the same thing…
- EVGAThe graphics card brand that built its whole reputation on Nvidia, then walked away from Nvidia on its own.
- Evgeniy BogachevRussian national the FBI says ran the GameOver Zeus banking botnet, and who for years carried the largest bounty ever…
- Evil bitA 2003 April Fools' RFC proposing that malicious IP packets should kindly label themselves as malicious.
- Evil Maid attackAn attacker with physical access to your laptop while you're away (in a hotel room, an office), modifies firmware or…
- evilwmA window manager with no title bars, buttons or menus: a one-pixel border, the keyboard for everything, and nothing that…
- EvokeOne of Europe's largest annual demoparties, held in Berlin since 2000, where demoscene artists compete and premiere…
- EVP_BytesToKeyOpenSSL's legacy function for turning a password into a key and IV — fast, simple, and unsuitable for exactly those reasons.
- EVPNEthernet VPN (RFC 7432) — a BGP-based control plane for distributing MAC addresses and L2/L3 information in overlay…
- EVPN multihomingThe way to attach a server or switch to two leaf switches at once with no proprietary link between them. The replacement for…
- EWMHThe extra rules that let taskbars, pagers and window managers from different projects understand each other under X11.
- EXAThe acceleration layer that replaced XAA in X.Org in 2005, built around XRender compositing instead of blitter operations…
- ExabyteThe backup tape that dragged a camcorder's 8 mm technology into the server room and held 2.5 GB when hard disks were…
- Exactly-once semanticsGuarantee in distributed messaging systems: each message is processed exactly once — never duplicated, never dropped…
- ExasolA German analytics database that topped the benchmarks by keeping everything in memory and in columns.
- ExcalidrawWhiteboard tool with a distinctive hand-drawn aesthetic. Created 2020 by Christopher Chedeau (Facebook). Open source MIT…
- ExceptionAn error that's "thrown" and bubbles up the call stack until something catches it with try/catch.
- Excess-3The BCD variant that adds three to every digit and gets subtraction almost for free in return.
- ExciteThe Stanford-born portal that passed on buying Google for less than a million dollars.
- Exclusion constraintThe generalisation of uniqueness: instead of requiring that two rows not hold the same value, you can require that they not…
- execThe system call that swaps a process's contents for another program — same process, new code.
- ExecutableA file the OS can load and run directly — contains machine code, metadata, and info on which libraries it needs.
- Executable graphicsA compo category in which the entry is a still image, but the image must be generated by an executable under a hard size…
- Exfiltration (Data exfiltration)Smuggle stolen data out of a compromised network — the last step in most breaches.
- Exhaustive matchCompiler feature: when you match on a union type, every variant must be handled explicitly. Rust match, Haskell case…
- Exif (Exchangeable image file format)Metadata standard that cameras embed in JPEG and TIFF files. Specified by JEIDA/JEITA, first version 1995. Contains…
- Existential forgeryProducing a valid signature or MAC for any message at all, even a meaningless one, already counts as a security failure.
- Exodus CommunicationsThe dot-com era's biggest data-centre operator, where half of Silicon Valley rented rack space — and which went bust when…
- ExomizerA cross-platform cruncher that squeezes data and executables for the whole 6502 family and unpacks them on the target…
- ExoticaAn archive that preserves the Amiga's game and demo music in its original formats — the C64 scene's HVSC, but for the Amiga.
- Expanded memory (EMS)The trick that got DOS past 640 kilobytes by swapping pieces of a larger memory through a small window.
- Expander (audio)The compressor's mirror image: it turns down what is already quiet, so the gap between soft and loud grows instead of…
- Expansion CardA plug-in hardware module that extended a computer's capabilities by adding sound, graphics, networking, or memory through a…
- Expedia GroupUS OTA conglomerate — Expedia, Hotels.com, Vrbo (Airbnb competitor), Trivago, Hotwire, Travelocity. Microsoft spinoff 1999.
- Expert parallelismDistributing an MoE model's experts across different GPUs so each card holds only a few. The form of parallelism that makes…
- Expert routerSmall neural network that decides which expert to send each token to in MoE. Usually a linear layer + softmax with top-k…
- Expert routingMechanism in MoE models: gating function that selects which 1-2 of N experts are activated per token. Critical for sparse…
- Expert system1980s AI: thousands of hand-written if-then rules that worked splendidly right up to the edge of their domain.
- EXPLAIN ANALYZESQL command that shows the database's execution plan + actual runtimes per step. The standard tool for SQL performance…
- EXPLAIN planThe EXPLAIN command shows how the database plans to execute your query — which indexes, joins, scans.
- ExploitCode or technique that takes advantage of a vulnerability to do something it shouldn't.
- Explore page / FYPThe algorithmically curated page of content from accounts you don't follow — Instagram's "Explore", TikTok's "For You Page"…
- ExpoA tooling layer on top of React Native that removes the need for Xcode and Android Studio in most cases.
- EXPO profileEXtended Profiles for Overclocking — AMD's equivalent of Intel's XMP for DDR5 memory. Enables a RAM module's…
- Exponential backoffRetry strategy where wait time doubles between attempts: 1 s, 2, 4, 8, 16… — protects against all clients hammering back…
- Exponential sine sweepA sine tone gliding logarithmically through the whole frequency range, used to measure the impulse response of a room or…
- Export-grade cryptographyDeliberately weakened ciphers and key lengths that US export rules allowed in the 1990s.
- Exposé (macOS)Panther's window overview from 2003: one press of F9 and every open window shrinks into a tidy mosaic — the effect that…
- Expose eventThe X server telling a program that part of its window has just become visible and needs painting — now.
- Express.jsMinimalist Node.js web server framework. TJ Holowaychuk, 2010. De-facto standard for a decade. Middleware-based architecture.
- ExpressionA code construct that evaluates to a value — 2 + 3, foo(), x ? a : b. Opposite: statement.
- Expression indexAn index on the result of an expression or function rather than on a column directly. CREATE INDEX ON users (lower(email))…
- ext4Default Linux filesystem for most distros (Ubuntu, Debian, Arch). Successor to ext3 (2008). Extent-based allocation…
- Extended Color Mode (ECM)A text mode in the C64's VIC-II that lets every character pick its background from four registers — at the cost of shrinking…
- External Secrets OperatorKubernetes operator that fetches secrets from an external store (Vault, AWS Secrets Manager, GCP Secret Manager, Azure Key…
- ExternalDNSKubernetes controller that auto-creates DNS records based on Service/Ingress objects. Annotate Ingress with…
- Extra Half-BriteAn Amiga display mode that turns 32 palette colours into 64 by adding the same colours at half brightness.
- Extreme NetworksA Gigabit switching pioneer that became the industry's collector of other people's networking divisions.
- ExynosSamsung's in-house system-on-chip — the engine in half the Galaxy world, while the other half got Qualcomm's Snapdragon.
- Eyal KushilevitzThe theorist who asked how to fetch a record from a database without the database learning which one, and then showed it…
- Eyal RonenIsraeli cryptographer who showed that smart light bulbs could carry a worm across an entire city.
- Eye adaptationAutomatically adjusting a scene's exposure over a second or two to mimic how a real eye adjusts when you step from daylight…
- Eye diagramThe picture you get when thousands of unit intervals of a serial link are drawn on top of each other. The single most…
- LLM evaluationMeasuring how "good" an LLM is. Multi-dimensional: knowledge (MMLU), reasoning (GPQA), code (HumanEval, SWE-bench)…
- On-die ECCError correction built into the DDR5 chip itself, fixing bit errors internally before data leaves the memory module…
F
- .forwardA text file in your home directory telling the mail server to send your mail somewhere else instead.
- 5GFifth generation mobile networks — faster, but the real difference lies in latency and in how many devices fit.
- Adobe FlashMultimedia platform for the web 1996–2020. SWF files in a browser plugin delivered animation, video, games, interactive…
- Apache FlinkStream-first compute engine — low latency, stateful processing, exactly-once semantics, event-time watermarks as a…
- AWS FargateServerless backend for ECS and EKS — AWS manages the VMs for you and you pay per vCPU-second your containers consume.
- Browser fingerprintIdentifying a user uniquely based on browser properties — without cookies.
- CrowdStrike FalconCloud-native EDR (Endpoint Detection & Response). CrowdStrike, founded 2011 by Dmitri Alperovitch + George Kurtz…
- Digital forensicsEvidence collection and analysis after a security incident — what happened, when, how far did the attacker get.
- F-SecureFinnish antivirus company from Helsinki that spent thirty years as the Nordic region's most visible voice in security.
- F#A functional-first language on .NET, built by the same person who got generics into C#.
- F1 scoreHarmonic mean of precision and recall — a balanced metric for classification models.
- F5 NetworksThe Seattle company behind BIG-IP, the box sitting in front of a remarkable share of the world's banking and government web…
- fa.*The Usenet groups that mirrored ARPANET mailing lists, so people without an ARPANET account could at least read what was…
- FAANGAcronym for five dominant US tech companies: Facebook (Meta), Apple, Amazon, Netflix, Google. Coined by CNBC's Jim Cramer in…
- Fabian GiesenGerman coder, known on the scene as ryg, who built Farbrausch's packer and capture tool and later took his compression…
- FABRIKAn iterative inverse-kinematics solver that drags a bone chain toward its target back and forth along the joints instead of…
- Face IDApple's face unlock, introduced with the iPhone X in 2017 — it projects 30,000 infrared dots and measures shape, not…
- FacebookThe world's largest social network — launched by Mark Zuckerberg from a Harvard dorm (February 2004), today ~3 billion…
- Facebook MarketplaceMeta's built-in peer-to-peer marketplace — launched 2016. Quickly the world's largest C2C service thanks to 3 billion…
- FacitThe Swedish firm that turned the pinwheel calculator into an export industry — and then became the textbook case of what…
- Factory patternGang-of-Four creational pattern — move object creation out of the client into a "factory" so the client doesn't need to know…
- FaderThe slider that sets a channel's level in a mix, and which DAWs still draw on screen out of sheer habit.
- Fail-fastCrash at the first sign something is wrong, rather than continuing in a state nobody understands any more.
- Fail2banReads log files, looks for patterns that resemble failed logins and blocks the source IP in the firewall for a while…
- FailoverAutomatic switchover to a backup when the primary component fails. Default in high-availability systems. Requires…
- Fair queueingPacket scheduling that gives each flow (TCP connection) equal share of bandwidth — instead of FIFO which gives advantage to…
- Fairchild F8Fairchild's 8-bit microprocessor from 1975 — the brain of the Channel F, the first games console with swappable cartridges.
- Fairchild SemiconductorThe chip company that made the integrated circuit practical, and then seeded half of Silicon Valley with its own staff.
- FairlightOne of the scene's oldest and longest-lived groups — it started cracking on the C64 in 1987 and still makes demos today.
- Fairlight CMIThe first commercial sampling workstation, an Australian computer costing around $25,000 that gave 80s pop its orchestra…
- FairphoneA Dutch phone maker that sells handsets you can take apart yourself, which in this industry counts as a radical idea.
- FAISS (Facebook AI Similarity Search)A library for fast similarity search across large collections of vectors, released by Meta in 2017. The engine under the…
- FalcoOpen source runtime security for Linux + Kubernetes. Sysdig 2016, CNCF Graduated 2024. eBPF-based. Detect anomalous…
- Falco rulesYAML config for Falco runtime security. Rules define conditions (syscall pattern, process name, file path), output message…
- Falcon LogScaleIndex-free log management that ingests and searches enormous log volumes in real time; built by Humio, bought by CrowdStrike.
- False sharingTwo threads write to different variables that happen to sit in the same cache line. The coherence protocol invalidates the…
- FamiTrackerThe Windows tracker for writing authentic NES music — the sound chip in a 1983 Nintendo, driven from a grid.
- FanRotating cooling for CPU, GPU and chassis — pushes hot air away.
- Fan-out packagingPackaging technique where dies are moulded into an artificial wafer with gaps between them, so the connections can be routed…
- Fan-out-on-writeA strategy for feeds where, on publishing, a post is copied out to all followers' precomputed "inbox" — so reading becomes…
- Fanfold paperPrinter paper as one long web, zigzag-folded along perforations — the data centre's standard medium for four decades.
- Fantasy consoleAn imaginary computer that exists only in software, with limits chosen on purpose to feel like an 8-bit machine.
- FAQA list of answers to questions nobody could face answering one more time, born on Usenet and mailing lists long before…
- FAR formatThe module format of Farandole Composer, a 16-channel DOS tracker from the mid-90s.
- FarbrauschA German demogroup that pushed procedural generation to its limit — a whole first-person shooter in 96 kilobytes.
- FarkNews aggregator from 1999 where every link gets a sarcastic rewritten headline and a tag telling you what to think. "Not…
- Fast correlation attackA refinement of the correlation attack that treats the keystream as a noisy codeword and decodes a register's state instead…
- Fast inverse square rootThe bit hack that approximates 1/√x by reading a float as an integer, subtracting it from a magic constant and polishing the…
- Fast retransmitResending a lost segment as soon as three duplicate acknowledgements arrive, instead of waiting out the retransmission…
- FastifyFast, low-overhead Node.js framework — JSON Schema–driven validation, ~30k req/s on a single core.
- FastloaderThe fast loader that made the C64's painfully slow disk drive bearable — by rewriting the loading protocol itself.
- FastlyThe CDN developers pick because they can program it, and the one the rest of the world learned about the day it went down.
- FastmailAustralian independent email provider — paid only ($3+/mo), fast web client, IMAP/JMAP standards crowd. Default choice among…
- FastTracker IIThe PC scene's dominant tracker of the 1990s — thirty-two channels, the XM format and an interface that set the standard.
- FAT (File Allocation Table)The 1977 filesystem still sitting in every USB stick, SD card and EFI partition.
- Father Christmas wormA DECnet worm that crawled across SPAN and HEPnet in December 1988, with the sole purpose of delivering a Christmas greeting…
- Fault attackA fault attack makes the hardware miscompute and reads the key out of the wrong answers.
- Fault injection attackAn attack that deliberately disturbs a cryptographic computation, for example with a voltage glitch or laser pulse, and…
- Faust (audio language)A functional language for signal processing in which programs are block diagrams, compiled down to efficient C++ or…
- FaviconThe little icon in the browser tab and in bookmarks.
- FaxThe machine that scanned a page, sent it as sound down a phone line, and printed a copy at the other end.
- FBXAutodesk's closed interchange format for 3D scenes – used by the entire games industry, owned by nobody but Autodesk.
- FCMGoogle's push service — Firebase Cloud Messaging, successor to GCM and Android's counterpart to APNs.
- FDE (Full Disk Encryption)All data on the disk is encrypted automatically. Key unlocks at boot (passphrase, TPM, smart card). Protects against…
- FDN (feedback delay network)A set of delay lines whose outputs are mixed through a matrix and fed back into their inputs – the skeleton of most modern…
- FDWForeign Data Wrapper — a PostgreSQL feature that lets SQL queries read from external sources (MySQL server, CSV file, REST…
- FEALNTT's fast DES alternative from 1987, remembered mainly as the punching bag on which nearly every new cryptanalytic…
- Featherstone's algorithmAn algorithm that computes the dynamics of a chain of jointed bodies in linear time — and is the reason some ragdolls' arms…
- Feature engineeringConstructing better inputs (features) for ML models — historically 80% of the work in classic ML.
- Feature flagRuntime switch that enables or disables features without a new deploy — enables trunk-based development, canary, A/B tests…
- Feature flag (ops)A switch in the code that lets you turn a feature on or off at runtime — without deploying new code. It decouples "deploy…
- FederationServer-to-server protocol where different instances talk to each other without a central authority. Email is the archetype…
- FediBlockA hashtag and informal practice in the Fediverse where instance administrators share information about problematic servers…
- FediPactA collective pledge (2023) among Mastodon instance administrators to preemptively block Meta's Threads when it federates via…
- FediverseUmbrella name for federated social platforms that speak ActivityPub — Mastodon, Pleroma, PeerTube (video), Pixelfed…
- Fediverse discovery problemFundamental problem in federated networks: how to find relevant accounts/posts without central index? Mastodon + Pleroma…
- Fediverse softwareDifferent servers that speak the ActivityPub protocol and can therefore federate. Mastodon dominates microblogging; variants…
- FedNowThe US central bank's instant payment service, arriving roughly a decade after Swedes had started settling restaurant bills…
- FedoraRed Hat's community distro — bleeding edge for later RHEL versions. Fedora Workstation, Server, CoreOS, Silverblue…
- Feed generator (Bluesky)A third-party service in Bluesky that produces a custom feed of posts according to any logic. Anyone can build and publish a…
- FeedlyAn RSS reader launched in 2008, best known for what happened in the summer of 2013: Google shut down Google Reader, and…
- Feistel networkThe construction that lets you build a reversible cipher out of a function that cannot be reversed.
- Félix DelastelleFrench cryptographer who invented the Bifid and Trifid ciphers at the turn of the twentieth century.
- Felix DomkeGerman hardware hacker who has broken into game consoles and, less predictably, a diesel car's engine controller.
- Felix LindnerBerlin hacker, better known as FX, who spent the 2000s demonstrating that routers are computers too.
- Felix von LeitnerGerman security consultant and programmer, known as "Fefe", whose blog has been one of Germany's most widely read since 2005.
- Fenced framesAn embedded frame deliberately stripped of all communication with the page around it. Built so it can display something…
- FeRAM (Ferroelectric RAM)Non-volatile memory based on ferroelectric polarisation of thin PZT film. Faster than flash, lower energy, but expensive per…
- Fermi Paradox (demo)Mercury's space demo that won the PC demo competition at Revision 2016 and showed that a demo can say something, not just…
- Fernando CorbatóThe MIT researcher behind the CTSS time-sharing system, and therefore the man who introduced the computer password, which he…
- Ferranti Mark 1The first computer an ordinary customer could buy off the shelf — the Manchester prototype turned into a product.
- Ferric oxideThe brown gamma iron oxide that was the first practical magnetic layer on tape and floppy disk — the original "normal" tape.
- Ferrite headThe early read/write head — a tiny ferrite core with a wire winding — that carried hard disks and floppies before thin-film…
- FET compressorA compressor that uses a field-effect transistor as a voltage-controlled resistor, letting it clamp down faster than almost…
- Fetch APIModern web API for HTTP requests. Promise-based, replaces XMLHttpRequest. WHATWG standard, broad browser support since 2017…
- Fetch streamingThe ability to read a fetch response piece by piece as it comes in, instead of waiting until the whole response has loaded…
- fetch()Modern JS API for HTTP calls — the replacement for old XMLHttpRequest.
- fetchpriorityHTML attribute (fetchpriority="high|low|auto") that hints to the browser which resources matter most — useful for jumping…
- Few-shot promptingGiving an LLM a few examples in the prompt before asking — the model mimics the pattern.
- FF1NIST's standard method for encrypting a number or string so the result has the same length and alphabet as the input.
- FF3FF1's faster sibling in NIST's format-preserving encryption standard — broken, patched, and broken again.
- FFmpegSwiss army knife for video/audio processing. Fabrice Bellard started in 2000. Convert, cut, encode, decode 1000+ formats…
- FFT (fast Fourier transform)The algorithm that splits a signal into its frequencies in n·log n steps instead of n² — which is what made digital audio…
- FialkaThe Soviet M-125 rotor machine that carried Warsaw Pact traffic for most of the Cold War.
- Fiber optics (Fibre optic)Data transmission via light in thin glass fibers. Single-mode (long range, narrow core) or multi-mode (short, wide)…
- FIDO2The pair WebAuthn (browser API) + CTAP (client → authenticator protocol) that enables passwordless, phishing-resistant login…
- FIDO2 / passkeyThe open standard behind passwordless, phishing-resistant login. On registration a cryptographic key pair is created: the…
- FidoGateA Unix package that translated between FidoNet and the internet: netmail to email, echomail to Usenet groups, and back again.
- FidoNetWorldwide message network between BBSes, built in 1984 by Tom Jennings on the observation that long-distance calls are…
- FidoNewsFidoNet's weekly newsletter: a text file passed from node to node, in which sysops argued about the network's future.
- field-sizingCSS property letting a form control size itself to its content instead of having a fixed default size.
- FIGletA program that turns ordinary text into big letters built out of ASCII characters.
- FigmaBrowser-based design tool that killed Sketch — multiplayer "Google Docs for designers". Adobe tried to buy it for $20B…
- File descriptorA small integer identifying something the process has open — a file, a socket, a pipe, a device.
- File echoFidoNet's way of distributing files — echomail, essentially, but carrying programs and archives instead of messages.
- File Manager (Windows)Windows 3.0's file manager with a directory tree on the left and a file list on the right, outclassed by Explorer in 1995…
- FILE_ID.DIZA ten-line text file inside an archive that let a BBS show a standardised description of the contents automatically.
- Fileless malwareMalicious code that runs entirely in memory without writing an executable file to disk — which makes it invisible to…
- filemgrThe OpenWindows File Manager in DeskSet: icon view, wastebasket and drag-and-drop to the other DeskSet tools, with file…
- FilesystemThe layer that turns a pile of numbered blocks into files with names, directories and permissions.
- Filippo ValsordaThe Italian cryptographer who writes boring, hard-to-misuse crypto code — and thinks that ought to be the norm rather than…
- Fill rateHow many pixels or texels a GPU can write per second — for a long time the hardest bottleneck in real-time graphics.
- Filled vectorsThe scene's name for rotating 3D objects with solid-coloured faces — the first real 3D in home computer demos.
- FillfactorA setting that controls how full an index/data page is packed at build, leaving the rest as free space for future…
- Film scannerA scanner that shines light through film rather than onto paper — built for slides and negatives, not documents.
- Filter bubbleThe idea that personalized algorithms show you more of what you already like and thereby invisibly shrink your picture of…
- Final Cartridge IIIAn all-in-one cartridge for the Commodore 64 with a fastloader, a freezer and a desktop interface.
- FinderThe Macintosh desktop program of 1984, which turned the file system into icons in windows and has outlived three operating…
- Fine-tuningTaking an already-trained AI model and training it further on your own data.
- Fine-tuning (LLM)Further training an already pre-trained language model on your own, more specific data to adapt it to a task, domain, or…
- FinFETThe transistor type that has dominated chip manufacturing since ~2011, where the channel stands up as a "fin" and the gate…
- FingerThe protocol that let anyone ask a machine who was logged in and how long since they last touched the keyboard.
- Finn.noNorway's Blocket — Schibsted sibling, same codebase history. Dominates Norwegian classifieds: cars, housing, jobs, "torget"…
- Finsta"Fake Instagram" — secondary account (usually private) where users post more authentically: unedited selfies, ranting, drunk…
- Finstagram (finsta)A second, private, anonymous Instagram account ("fake Insta") followed by only a small circle of close friends, where you…
- FIPS 140FIPS 140 is NIST's standard for validating cryptographic modules, and anyone buying an HSM asks for the certificate first.
- FIR filterA digital filter that only looks at incoming samples, never at its own output — so it is always stable and can be made…
- Fire effectThe flame that creeps up the screen — a cellular automaton in a couple of lines of code and a well-chosen fire palette.
- FirebaseGoogle's BaaS (Backend-as-a-Service) platform — authentication, database (Realtime DB + Firestore), hosting, push…
- FireboltCloud data warehouse positioned as "Snowflake but faster for analytics dashboards". Israeli startup, launched 2020.
- FirecrackerMinimalist VMM from AWS, written in Rust — boots a KVM-based micro-VM in under 125 ms with a memory footprint under 5 MiB.
- FireEyeA network-security firm that detonated suspicious code in virtual machines to catch zero-day threats — and in 2020 exposed…
- FirefishThe Misskey fork formerly called Calckey, renamed in 2023. For a while it was the most popular Western Misskey variant, but…
- Firestore (Cloud Firestore)Google's managed NoSQL document database — successor to Firebase Realtime Database, ships with realtime listeners.
- FirewallA guard that inspects network traffic and lets through what matches the rules.
- Firewalls and Internet SecurityBill Cheswick and Steve Bellovin's 1994 book, the first to teach a broad audience how to build a firewall.
- Firing tableThe booklet telling a gun crew how high to point the barrel — and the arithmetic backlog that became the reason to build…
- FirmwareSoftware embedded in hardware — lives in routers, printers, SSDs, IoT devices.
- First DataOmaha payment processor that for decades handled a large share of all card purchases in the United States.
- First Draft of a Report on the EDVACAn unfinished 101-page manuscript from June 1945 that defined the modern computer — and in the same stroke made it…
- First-hop redundancy (FHRP)The umbrella name for protocols that provide redundancy for the default gateway: several routers share a virtual IP/MAC, so…
- FiservAmerican supplier of core banking and payment processing, invisible to customers but wired into thousands of banks.
- Fish shell"Friendly Interactive SHell" — fish syntax-highlights, suggests from history, has tab-complete out of the box. Diverges from…
- FitbitThe company that turned the pedometer into an everyday health-data machine — and whose data ended up at Google.
- FivetranFully managed ELT service — 500+ connectors from SaaS and databases into Snowflake/BigQuery/Redshift with zero maintenance.
- FIX (Federal Internet Exchange)The two meeting points where US government networks swapped traffic around 1990.
- Fixed timestepRunning the simulation at a constant timestep independent of the render rate, carrying leftover time in an accumulator.
- Fixed-pointRepresenting fractional numbers as integers with an implied, fixed decimal point. Store 12345 and know the scale is 100, and…
- fj.*Japan's Usenet hierarchy, "from Japan" — where Japanese text first learned to squeeze through a network built for seven-bit…
- FL StudioBelgian developer Image-Line's DAW, which started life as a simple drum-loop toy called FruityLoops and became the bedroom…
- FLAC (Free Lossless Audio Codec)Lossless audio compression — roughly half the file size of WAV, with bit-for-bit identical playback.
- Flag day (1983)1 January 1983, when ARPANET switched from NCP to TCP/IP in one go.
- FlaggerAn operator that runs canary rollouts automatically: shifts traffic in small steps, checks that error rate and latency hold…
- Flair (Reddit)Small labels/badges on Reddit set either on posts (category, e.g. "Question", "News", "Spoiler") or next to a user's name in…
- Flame warAn online argument that has stopped being about the subject and become an endurance contest between two people who both…
- FlangerThe sound of a jet engine passing through a guitar — a comb filter whose teeth sweep up and down.
- FlannelThe original "simple Kubernetes CNI" — gives each node a subnet and ships pod traffic between nodes over a VXLAN overlay.
- Flash AttentionSmart implementation of the attention mechanism — uses GPU fast memory efficiently, 2-4x faster with the same result.
- Flash memoryNon-volatile memory — retains data without power. The foundation under SSDs, USB sticks, SD cards, and smartphone storage.
- Flash Translation Layer (FTL)The software in an SSD controller that translates the operating system's logical addresses to physical NAND addresses. The…
- FlashAttention-2Memory-efficient attention implementation. Tri Dao 2023 (FA-1 2022). Reformulates self-attention for better GPU memory…
- Flat shadingOne lighting value per polygon — the whole triangle gets a single colour and the surface looks faceted.
- Flatbed plotterA plotter where the paper lies still on a flat bed while a pen arm travels in both X and Y across the surface.
- Flatbed scannerA desktop scanner where the document lies still on a glass platen while a sensor bar sweeps beneath it.
- FlatBuffersGoogle's serialisation format (2014) — like Protobuf but without the parsing step. You read field values directly from the…
- Flatcar Container LinuxA minimal Linux distribution whose only job is running containers. Started in 2018 by Kinvolk as a fork of CoreOS Container…
- FlatpakLinux package system focused on desktop applications — sandboxed via bubblewrap, runtime sharing to avoid duplicating libs.
- FLDA C64 trick that pushes the screen downward line by line by cheating the VIC-II out of its bad lines.
- FlecsAn archetype-based ECS framework written in C with a C++ API, known for treating relationships between entities as…
- Fleißner grilleA rotating grille cipher that reads the plaintext through holes in a template turned four times.
- FlexASIOAn open-source universal ASIO driver that makes any Windows sound device look like an ASIO device, with your choice of audio…
- FlexboxCSS layout model for one-dimensional arrangements — rows or columns. display: flex on the container. Solved the…
- FlexowriterThe paper-tape-driven typewriter that served as input and output for many early computers.
- FlextronicsOne of the world's largest contract electronics makers — it builds other companies' products, rarely its own.
- FLI (graphics mode)A C64 trick that forces the VIC-II to fetch fresh colour data every scanline, giving far more colours than the standard…
- FlickrWeb 2.0 era photo-sharing site — sold to Yahoo, neglected, rescued by SmugMug in 2018.
- Flip-flopThe circuit that remembers a one: two elements holding each other down until something pushes them over.
- FlipbookA sequence of images played in order to create motion — in games usually a grid of sub-images packed into a single texture.
- Flippy diskA single-sided floppy that users flipped over to record on the back — a cheap route to double the capacity.
- Float (Floating-point)Approximation of real numbers via IEEE 754. Different precisions: float16 (16 bits, ML), float32 (single, default), float64…
- Floating IPAn IP address that can be moved between servers — for failover without DNS changes.
- Floating originMoving the entire world so the camera always sits near the coordinate system's zero point, because floats lose precision…
- Floating pointThe computer's way of representing decimal numbers — the IEEE 754 standard. Classic source of the "0.1 + 0.2 ≠ 0.3" bug.
- Floating static routeA static backup route with a deliberately high administrative distance, so it lies "dormant" until the primary route…
- Floating-point unit (FPU)The part of the processor that performs calculations on floating-point numbers (decimal numbers with a movable decimal…
- Flood fillFills a connected region of like-coloured pixels from a seed — the paint-bucket tool.
- FloodgapThe Gopher server that kept the protocol alive after nearly everyone else switched off, and home of the Veronica-2 search…
- Floppy diskLasted thirty years, held 1.44 megabytes, and is still the "save" icon in software written by people who never handled one.
- Floppy disk formatsThe jungle of capacities — 160 KB, 360 KB, 720 KB, 1.2 MB, 1.44 MB — that fell out of density, number of sides and sector…
- Floptical1991 floppy drive that stamped optical servo tracks into the medium to squeeze 21 MB out of a 3.5-inch disk.
- Flow controlMechanism to keep a fast sender from overwhelming a slow receiver. At the network layer (TCP), application layer (HTTP/2…
- Flow diagram (1947)Goldstine and von Neumann's notation for planning a program before coding it — ancestor of the flowchart, minus the proof…
- Flow fieldA vector field over the grid where every cell points to the next step toward the goal, so hundreds of units can share one…
- Flow mapA texture whose pixels store direction, used to make another texture appear to stream along a surface — water, lava, mud.
- Floyd-WarshallAll-pairs shortest-paths algorithm — computes the shortest path between every pair of nodes. Robert Floyd / Stephen Warshall…
- Floyd–Steinberg ditheringA 1976 error-diffusion algorithm that renders grey tones on a one-colour printer or screen by spreading the rounding error…
- FLP impossibility (Fischer–Lynch–Paterson)Proved in 1985 that no deterministic asynchronous consensus algorithm can guarantee both liveness and safety if even a…
- FLTKThe Fast Light Toolkit: a C++ toolkit from 1998 that draws its own widgets, is small enough to link statically into every…
- Fluent BitLightweight (~5 MB) C-written log forwarder — successor to Fluentd (Ruby), the default DaemonSet in many Kubernetes clusters.
- Fluentd / Fluent BitLog collector that accepts logs from all sorts of sources and routes them to different destinations.
- Fluid simulationSolving a fluid's motion in real time — on a grid or as a swarm of particles — and faking it wherever you can get away with…
- FluidSynthOpen-source real-time synthesizer that plays MIDI through SoundFont files, quietly embedded in a long list of programs that…
- FlutterGoogle's cross-platform framework — one codebase (Dart) builds iOS, Android, web, desktop. Own render stack (Skia, then…
- Flux (GitOps) (Flux CD)The GitOps tool that coined the term — continuously reconciles a Kubernetes cluster against a Git repo.
- FLUX (image model) (FLUX.1 / Schnell / Pro)Image-model family from the ex-Stability founders (Robin Rombach et al.) — Schnell (open), Dev (non-commercial), Pro…
- Flux CDGitOps operator for Kubernetes — polls a Git repo, applies the manifests in the cluster, and continuously reconciles drift.
- Flux transitionThe point on the medium where magnetisation reverses direction — the physical event that all magnetic storage fundamentally…
- FluxboxA 2001 Blackbox fork that added tabs, a dock area and key bindings without putting on weight.
- flwmThe Fast Light Window Manager: Bill Spitzak's window manager built on his own FLTK, with wm2's vertical title bar and very…
- Fly.io"Heroku that flies globally" — runs Docker apps in Firecracker microVMs across 35+ regions with automatic anycast routing.
- Flying heightThe nanometre-scale gap between head and platter — the single biggest lever on areal density.
- FlywayDatabase migration tool. SQL files numbered V1__create.sql, V2__add_index.sql. Java/JVM ecosystem standard. Open source…
- Flyweight patternLetting thousands of objects share whatever they have in common, so each carries only what makes it different.
- FM encodingThe first recording code for floppies — simple, robust and wasteful, since every other flux transition was nothing but a…
- FM encoding (single density)The earliest magnetic-disk encoding, where every bit cell opens with a clock pulse — at the cost of half the density.
- FM synthesisBuilding timbres by letting one oscillator wobble another's frequency at audio rate, so two plain sine waves produce a dense…
- fmapHaskell function on the Functor typeclass. Apply a function to value(s) inside a container without unwrapping. fmap (+1)…
- FMODA game audio engine that began as a demoscene library for playing tracker modules and ended up in thousands of commercial…
- FMS attackThe attack on RC4's key schedule that turned breaking WEP from a research problem into a hobby.
- FocusWhich element receives keyboard input — marked by a focus ring.
- Focus follows mouseThe focus policy where keystrokes go to whichever window the pointer is over, no clicking required.
- Focus stealing preventionThe window manager's rules for stopping a newly opened window from grabbing keyboard focus while you are typing in another…
- Focus trapThe technique of keeping keyboard focus confined inside an active element (usually a modal/dialog) so that Tab navigation…
- FocusIn and FocusOutThe pair of events the X server sends when keyboard focus moves from one window to another — technically precise, and for…
- FocusriteBritish company that started out making exclusive console modules and ended up selling the red USB box found on half the…
- Fog Creek SoftwareThe New York software shop whose most important product may have been its founder's blog.
- Fog of warThe strategy-game device that hides the parts of the map no friendly unit currently sees, and shows already-explored but…
- Foliage renderingThe umbrella name for the techniques that draw large amounts of grass, trees and bushes without choking the frame rate.
- FollinaCVE-2022-30190 — RCE via Word document → MSDT (Microsoft Support Diagnostic Tool) ms-msdt: URL handler. Worked even with…
- Follow backSocial norm: if someone follows you, follow back. Abbreviated "FB" or "F4F" (follow for follow). Standard reciprocity…
- Follow baitPosts designed to maximize follower acquisition vs information value. Twitter thread with "follow @x for more" CTA, LinkedIn…
- Follower countNumber of followers/subscribers on a social-media account. Historically the primary status metric. Modern: engagement rate…
- Follower readLetting a replica answer reads without asking the leader, by only reading at a timestamp guaranteed to be fully replicated…
- Followup-ToThe Usenet header that decided where replies to a post would go, regardless of where the post itself appeared.
- Font AwesomeIcons smuggled in as a typeface, so they could be coloured and scaled with ordinary CSS.
- Font cartridgeA ROM module that slotted into the front of a printer and gave it letterforms it did not carry on board.
- Font path (X11)The list of directories and font servers the X server searches when a client asks for a font by name, and the most common…
- Font renderingTurning a letter's mathematical outlines into pixels — harder than it sounds, and why text looks different across systems.
- font-display: swapA CSS descriptor (in @font-face) that controls how text is shown while a web font loads. swap shows the text immediately in…
- FontconfigThe library that answers "which font file should I use for bold sans-serif with Cyrillic?", and which stopped Linux from…
- Foot IKAdjusts the leg bones with inverse kinematics at runtime so feet plant on the ground instead of floating above or sinking…
- For loopMost common loop construct. Classic C syntax: for (init; condition; increment). Modern variant: for-each / for-in that…
- Forbidden attackAn attack on AES-GCM that exploits reuse of a nonce, which exposes the authentication key.
- ForcepointAmerican security vendor rooted in Websense, focused on data loss prevention (DLP) and secure web and cloud gateways.
- Forecast factoryLewis Fry Richardson's 1922 thought experiment: 64,000 people in a circular hall, each responsible for one square of the…
- Foreign keyA column that references a primary key in another table — builds the relationship between tables.
- Foreign tablesPostgreSQL concept: a table definition that maps to external data via FDW. Read-only typically; some FDWs support write. A…
- ForgeRockIdentity company built by former Sun staff on the remains of OpenSSO after Oracle lost interest in it.
- ForkA copy of a project that goes its own way — either as a friendly contribution flow or as a divorce.
- Fork bombA process that spawns copies of itself exponentially — fills the process table in seconds and crashes the system.
- Form bursterThe machine in the old computer room that tore the endless strip of listing paper into separate sheets along the…
- Form factorThe agreed physical shape of a component — dimensions, screw holes and connector positions that let parts from different…
- Form feedThe FF control character (0x0C) that tells a printer to eject the current page and move to the top of the next.
- Formal verificationA mathematical proof that a program meets its specification — testing shows that bugs are present, formal verification shows…
- FormantA resonant peak in the voice's spectrum, shaped by throat and mouth — what makes an "ah" an "ah" at any pitch.
- Format overheadThe space eaten by gaps, sync fields, sector headers and ECC — which is why a "1.44 MB" floppy never holds 1.44 MB of…
- Format-preserving encryption (FPE)Encryption whose output has the same format as its input, such as a 16-digit card number that stays 16 digits.
- Formation movementMakes a group of units move together in a set pattern — line, wedge, box — while still avoiding obstacles and each other.
- FormatterTool that automatically formats your code to a style standard — no more debating tabs vs spaces in every review.
- FormspringA service where you publicly answered questions from others, often anonymous. It took off among teenagers in 2010 and became…
- FortifyStatic analysis that hunts for vulnerabilities straight in the source code, before the program has even run.
- FortinetThe firewall vendor that bet on custom silicon and sold one all-in-one box to offices that couldn't afford five separate…
- FortniteEpic Games battle-royale game — Fortnite Battle Royale launched 2017, killed PUBG momentum. Free-to-play, monetised via…
- FortnoxThe Växjö company that got Swedish small businesses to stop mailing binders to their accountants.
- FortranThe first high-level language to see wide adoption, released by IBM in 1957 with John Backus leading the project. The name…
- Fortuna (PRNG)A 2003 cryptographic random number generator designed so that nobody has to guess how much entropy it has collected.
- Forward kinematicsComputing where the end of a joint chain lands given all its joint angles — the easy direction, the opposite of inverse…
- Forward renderingThe classic pipeline: each object is rasterized and shaded in one pass, looping over the lights that reach it.
- Forward secrecy (PFS)Security property: even if the server key later leaks, previously eavesdropped traffic can't be decrypted.
- Forward+Tiled forward rendering: split the screen into tiles, cull the light list per tile, then shade in a single forward pass that…
- Forwarding / bypassA technique that sends a computed result directly from the execution unit that produced it to the instruction that needs it…
- FOSSIL driverA serial driver for DOS that let BBS software and door games talk to the modem without caring about the hardware underneath.
- Foundation modelA large "base model" trained on enormous data, then adapted to different tasks via fine-tuning or prompting.
- FoundationDBDistributed ordered key-value database with strictly serializable ACID transactions across the whole cluster — Apple's…
- Foundry NetworksThe switch maker whose fast Ethernet boxes wired the dot-com era's server rooms — and whose IPO was one of the period's most…
- Four-square cipherEncrypts pairs of letters using four 5×5 grids, two of them scrambled by keywords.
- FoursquareThe app where people once competed to be "mayor" of their local café, and which quietly turned into a location-data supplier.
- Foveated renderingRenders the centre of the image at full resolution and the periphery progressively coarser, since the eye only sees sharply…
- FoverosIntel's technique for stacking pieces of silicon on top of each other, with an active base die that both carries the upper…
- Fox EngineKonami's engine for Metal Gear Solid V: lavish, impressive, and effectively abandoned once its makers walked out.
- FoxconnThe factory behind other people's logos — the company that actually assembles your phone.
- FP88-bit floating-point format for deep learning — half the size of FP16, double the tensor throughput on Nvidia Hopper/Ada and…
- FP8 trainingTraining in eight-bit floating point. Roughly twice as fast as BF16, and requires tracking scaling factors so the numbers…
- FPGA (Field-Programmable Gate Array)Chip whose logic can be reprogrammed after manufacturing — sits between a CPU (flexible, slow) and an ASIC (fast, fixed).
- FPPA C64 technique where code decides, raster line by raster line, which line of graphics the VIC-II shows — so an image can be…
- FPS (Frames Per Second)Number of images displayed per second. Film standard: 24 fps. TV: 25–30 fps. Gaming PC mainstream: 60 fps, gamers: 144–240…
- fq_codelLinux qdisc: Fair Queueing + Controlled Delay. Default in Linux 3.6+ (2012). Combines per-flow fair queueing (mice protected…
- fr-041: debrisFarbrausch's 2007 demo in which a city tears itself apart on screen — from a file of under 180 kilobytes.
- fr-08: .the .productFarbrausch's breakthrough: a 64-kilobyte intro from 2000 that looked like a demo a hundred times its size.
- fr.*The French-language Usenet hierarchy, which succeeded FNET's groups and was run by its own committee.
- Fractal Brownian motion (fBm)Stack several layers of noise — each at double the frequency and half the amplitude — until the result has detail at every…
- Fractal DesignGothenburg-based maker of PC cases with a pared-back Nordic aesthetic — founded in 2007.
- Fractal tree indexA B-tree that collects writes in buffers on the way down instead of walking all the way to the leaf every time.
- Fractal zoomerA real-time dive into the Mandelbrot or Julia set — an effect that was long impossible, and therefore as much a technical…
- Fractional Brownian motion (fBm)Summing several octaves of a base noise — each at higher frequency and lower amplitude — into self-similar fractal detail…
- Fractional delayDelaying a digital signal by a non-integer number of samples — which means guessing what lay between the samples.
- Fractionated MorseMorse code is split into groups of three symbols, and each group is swapped for a letter through a keyed alphabet.
- FractionationA technique that splits each plaintext letter into several smaller symbols before rearranging them.
- Fragment shaderThe program run once per candidate pixel that decides what colour it gets.
- Fragmentation (IP fragmentation)Splitting an IP packet that's too large for the next link's MTU. The pieces travel separately and are reassembled only at…
- FRAM (Ferroelectric RAM, TI branding)TI's marketing term for FeRAM (same tech) — popular in their MSP430 FRAM MCUs for ultra-low-power battery IoT.
- Frame allocatorA linear memory allocator that hands out scratch memory during a frame and resets in one sweep when the frame is done.
- Frame budgetHow much time each frame is allowed to cost — 16.7 milliseconds at 60 fps — split up like a budget between the game's…
- Frame dataHow many frames a move takes to start up, hit and recover from — fighting games' exact currency for what is safe and what…
- Frame generationWeaving entirely synthetic frames in between the rendered ones — more frames per second with no extra rendering work, at the…
- Frame pacingDelivering frames at even time intervals — uneven frame times bother the eye more than a lower but steady frame rate.
- Frame skipSkipping the drawing of some frames when the machine can't keep up, so the game runs at the right speed even when it looks…
- FramebufferA region of memory holding the pixel values for one complete frame; the display reads it out while the GPU draws the next…
- FramerDutch design tool that pivoted from being a Figma competitor (prototyping) to being a website builder in 2022 — a Webflow…
- Framer MotionAnimation library for React — declarative syntax via <motion.div animate={{ x: 100 }} />. Spring physics, layout animations…
- FrameworkA pre-built structure that handles common tasks so you can focus on your specific business logic.
- Framework ComputerLaptops where every part can be swapped with the screwdriver in the box, which in this industry counts as a radical business…
- Francis WalsinghamElizabeth I's principal secretary and spymaster, who built a network of agents and mail interceptors across Europe.
- Frank McSherryCo-inventor of differential privacy who later changed lanes and started building streaming databases.
- Frank PiessensKU Leuven professor whose DistriNet group has become one of Europe's most prolific sources of hardware and protocol attacks.
- Frank RiegerGerman security engineer and Chaos Computer Club spokesperson with one foot in encrypted telephony and the other in the…
- Frank RowlettAmerican cryptanalyst who led the team that reconstructed the Japanese PURPLE machine in 1940.
- Frank StajanoCambridge researcher who explained wireless device pairing with ducklings, then studied con artists to understand why people…
- Franklin Computer CorporationThe Apple II cloner whose copied ROM handed the US the precedent that firmware and object code are copyrightable.
- FraviaThe Italian whose website served as the 1990s university of reverse engineering.
- Freax (book)The first serious attempt to write the history of the demoscene as a book — which stopped after volume one.
- Fred CohenThe grad student who wrote a self-spreading program on a VAX in 1983 and got his advisor to call it a virus.
- Fred Fish disksThe numbered series of free Amiga software that Fred Fish gathered and spread on floppy from 1986.
- Fred GramppBell Labs researcher who in 1984 co-wrote one of the first clear-eyed accounts of how Unix systems actually get broken into.
- Freddie WilliamsThe radar engineer who stumbled into the first random-access digital memory, then handed the whole computer business to his…
- Frederic WilliamsThe engineer whose cathode-ray tube became the first random-access memory, and whose test rig for it became the world's…
- Frederik VercauterenBelgian cryptographer whose surname is the V in BFV, one of the two homomorphic schemes nearly every library implements.
- Free space mapPostgreSQL's approximate register of how much room is left on each page of a table. The answer to "where do I put this row".
- Free-NetFree local dial-up networks that gave ordinary residents email, Usenet and forums before commercial internet providers…
- FreeBSDThe largest BSD descendant — a complete operating system rather than a kernel plus a distribution.
- freedesktop.orgThe meeting place that in 2000 set out to make GNOME and KDE work on the same screen, and became the home of X.Org, Wayland…
- FreenodeThe IRC network that served as free software's living room for a quarter of a century, until a change of ownership sent all…
- FreeSyncAMD's variable-refresh-rate technology — the monitor syncs its refresh rate to the GPU. Royalty-free, built on VESA…
- FreeverbA small reverb algorithm given away in 2000 that has since ended up in nearly every piece of open-source audio software.
- freeWAISThe free continuation of the WAIS code, which kept full-text search running on university servers after its authors went off…
- Freezer cartridgeA plug-in module with a button that freezes the running machine, dumps memory and backs up almost anything — copy protection…
- Frequency analysisE is the most common letter in English — and that alone is enough to break any cipher that fails to hide the statistics.
- Frequency Modulation SynthesisA synthesis method in which one oscillator's frequency is modulated by another, yielding rich, complex tones from simple…
- Frequency responseHow much a device boosts or cuts each frequency — the curve that shows whether it reproduces what it is given or adds…
- FrescoThe X Consortium's 1990s attempt to replace Xt and Motif with an object-oriented toolkit built on CORBA, which shipped with…
- FreshworksAn Indian SaaS company that owes its existence to a competitor's price hike.
- Fresnel effectEvery surface turns more mirror-like the more edge-on you view it — which is why a lake glitters near the horizon but is…
- Friction feedPaper advance in which a rubber-covered roller grips the sheet by friction — the same trick a typewriter uses — instead of…
- FridenCalculators from a Swedish emigrant who walked out of Marchant in a temper and built the rival that was first to take a…
- Friðrik SkúlasonIcelandic programmer behind the F-Prot antivirus and co-author of the industry's first shared naming scheme for viruses.
- Friedman testA method for estimating the key length of a polyalphabetic cipher from the index of coincidence.
- Friedrich KasiskiPrussian army officer whose 1863 method exposed the weakness of the Vigenère cipher.
- FriendicaOldest active Fediverse software — started 2010 (before ActivityPub existed). Facebook-like UI: news feed, friends, events…
- FriendsterThe first social network to break through, launched in 2002. It died not of a competitor's brilliance but of pages that took…
- FromSoftwareThe Tokyo studio that invented the "soulslike" by refusing to explain itself — from King's Field to Elden Ring.
- Front Panel (CDE)The wide bar across the bottom of a CDE screen, holding the clock, launchers, trash can and the four workspace buttons: a…
- FrontDoorA Swedish-developed FidoNet mailer for DOS that became the default choice for thousands of BBSes around 1990.
- FrontendThe part of a system that runs in the user's browser or app — what they actually see and click.
- FrostbiteEA's in-house game engine from DICE — built for Battlefield's destructible environments, later forced onto EA's entire…
- FroxelA voxel in a grid aligned to the camera's view frustum rather than to the world's axes.
- Frustum cullingDiscarding everything outside the camera's field of view before it is ever handed to the GPU.
- FSDP (Fully Sharded Data Parallel)PyTorch's built-in way of training models that do not fit on one card. It corresponds to ZeRO stage three: weights…
- FSM (Finite State Machine)Model where the system is in one of N states and only certain transitions are allowed.
- FSP (File Service Protocol)A lightweight UDP file transfer protocol from 1991, designed to load a server so little that nobody would notice it was…
- FSRAMD's open upscaling technology: render the game at a lower resolution and reconstruct a sharper image — hardware-agnostic…
- fsxNetA present-day "othernet" running FidoNet's protocols between BBSes over the internet, started in 2015 by New Zealander Paul…
- fsyncThe system call that forces writes out of the kernel's page cache onto durable storage. Without it your "saved" file merely…
- FTN (FidoNet Technology Network)The umbrella term for every network that runs on FidoNet technology without being FidoNet — same software, own nodelist, own…
- FTP (File Transfer Protocol)Classic protocol for moving files between computers — invented in 1971, still in use.
- FTPmailServices that fetched files from FTP archives for people who only had email, and mailed them back in pieces.
- FTSCThe FidoNet Technical Standards Committee — the network's answer to the IETF, with numbered documents instead of meetings in…
- FTTxThe collective label for how far the fibre actually runs before copper takes over — x stands for the endpoint.
- FujifilmThe film company that, unlike Kodak, survived digitization — partly by making the tape inside nearly every LTO cartridge.
- FujitsuJapan's answer to IBM, with two world-beating supercomputers and a British miscarriage of justice on its record.
- full_page_writesPostgreSQL writes the whole eight-kilobyte page to the transaction log the first time it changes after each checkpoint. The…
- Full-stackA developer who handles both frontend and backend.
- Full-text searchSearch through free text with ranking, stemming, fuzzy matching — not just LIKE '%foo%'.
- FuncomA Norwegian studio that made online role-playing games before they were an industry and troubled launches before they were a…
- FunctionReusable block of code with a name, parameters and (usually) a return value.
- Function callingThe ability of an LLM to, given a set of predefined functions with schemas, choose which one to call and produce the…
- Function tables (ENIAC)Three cabinets of hand-set switches held the numbers the machine could not work out for itself — and in 1948 turned ENIAC…
- Functional programmingParadigm where computation is expressed as composition of pure functions — no mutable state, no side effects, values flow…
- FunctorA data structure you can map over — implements map/fmap that applies a function to the "contents" without changing the…
- FUNETFinland's university network, whose FTP server is where Linux was first published.
- FunkwhaleSelf-hosted music streaming and sharing in the Fediverse. ActivityPub-based — instances can federate so you can follow music…
- Funnel algorithmExtracts the true shortest path through a corridor of navmesh triangles once pathfinding has worked out which triangles the…
- FuriosaAISouth Korean challenger whose inference chips aim to take on Nvidia on large language models — and reportedly turned down…
- FurnaceA modern open-source chiptune tracker that emulates an unusually large number of sound chips in a single interface.
- FuserThe hot roller in a laser printer that melts toner permanently into the paper — which is why the page comes out warm.
- Fusion-ioThe company that put flash straight on the PCIe bus years before NVMe, and hired Steve Wozniak as chief scientist.
- FutexThe lock that is free when nobody is fighting over it — fast userspace mutex, the building block under Linux thread…
- Future ComposerAmiga music editor and format that built notes from synthetic waveforms instead of samples, yielding tiny game music.
- Future CrewThe Finnish demogroup behind Second Reality — arguably the most influential force of the PC scene's golden years.
- Fuzz (guitar effect)The guitar effect that clips the signal so hard the waveform turns almost square — a technical fault that became a genre.
- FuzzballDavid Mills's little LSI-11 routers, which formed the very first NSFNET backbone in 1986 and were where NTP grew up.
- FuzzingA testing technique that feeds a program enormous amounts of random, malformed, or unexpected input to find crashes, memory…
- FVWMThe frugal, endlessly configurable window manager that was the default desktop on early Linux.
- FVWM modulesFVWM's way of growing without bloating: the pager, button bar, taskbar and icon manager are separate processes that talk to…
- fvwm95FVWM repainted as Windows 95 — taskbar, Start button and three buttons in the top-right corner of the title bar — so Linux…
- FXAAAnti-aliasing that runs as a post-process pass on the finished frame — it hunts for edges in the brightness and blurs them…
- FXPThe trick of making two FTP servers shovel a file directly between themselves while the client only conducts — the highway…
- fzfA general-purpose fuzzy finder for the terminal, written in Go by Junegunn Choi (2013). It takes anything on standard input…
- Postgres FDWForeign Data Wrapper for PostgreSQL — query data from external sources as if they were local tables. postgres_fdw…
- VPC Flow LogsAWS feature that logs metadata about every network packet in a VPC — who, where, how much, accepted or rejected. For…
G
- G-bufferThe set of render targets deferred shading fills in its first pass — a per-pixel description of the surface before any light…
- G-SyncNvidia's variable-refresh-rate technology — historically required a hardware module in the monitor; today mostly a…
- G.711 (μ-law and A-law)The phone network's audio encoding: 8 bits per sample on a logarithmic scale, giving quiet sounds finer steps than loud ones.
- G64A disk image that stores the 1541's raw GCR bitstream instead of finished sectors — so it can reproduce copy protection a…
- Gabe NewellThe Microsoft defector who founded Valve and grew Steam into PC gaming's default storefront — then declined to make…
- Gabriella ColemanAnthropologist who studies hackers the way her colleagues study villages: by living among them for years.
- Gadget (Motif)A Motif component with no X window of its own: the parent draws it and hands it its events, and in return the server is…
- Gaëtan LeurentFrench cryptanalyst who makes theoretical weaknesses cheap enough that nobody can keep calling them theoretical.
- GAFAMThe European variant of FAANG: Google, Apple, Facebook, Amazon, Microsoft. Includes Microsoft, excludes Netflix.
- Gain stagingKeeping the right level at every point in the signal chain, so nothing sits near the noise floor and nothing hits the…
- Gal BeniaminiIsraeli security researcher who showed that the most trusted parts of a phone are often the least examined.
- Galaxy FoldSamsung's first mass-market foldable phone, from 2019 — and a cautionary tale about shipping review units that break.
- Galera ClusterA synchronous multi-master cluster solution for MySQL/MariaDB (Codership). All nodes can take writes, and a transaction is…
- GalileoThe EU's satellite navigation system. First test satellites in 2011, initial services live since December 2016. Around 30…
- Gallium Nitride (GaN)Wide-bandgap semiconductor material (3.4 eV vs silicon's 1.1 eV) — enables faster switching, higher voltages, less cooling…
- Galois fieldA finite field with 2n elements; GF(28), with 256 elements, is the arithmetic AES is built on.
- Game BoyThe worst technology won: a grey screen with no backlight, but thirty hours on four batteries.
- Game engineSoftware framework for building video games — rendering, physics, audio, animation, scripting, editor. Saves time vs…
- Game feelThe tactile, moment-to-moment sensation of controlling something in a game — the sum of response, animation and feedback…
- Game juiceThe extra layer of feedback — shakes, particles, bounce and sound — that makes an action feel satisfying without changing…
- Game loopThe loop that drives everything in a game: read input, update the world, draw a frame, repeat.
- Game moddingWhen players rebuild the game — and occasionally build something bigger than the original.
- Game state stackA way of organising a game's modes — menu, gameplay, pause, inventory — as a stack where the top mode is in charge and the…
- GamebryoA licensable 3D engine, originally called NetImmerse, that sat underneath a surprising share of the 2000s' Western RPGs.
- GameMakerA 2D-focused game engine with a low barrier to entry — from Mark Overmars' hobby project in 1999 to the platform behind…
- GameObjectUnity's basic building block: an empty container with a position that only becomes something once components are attached.
- Gameplay Ability System (GAS)Unreal Engine's framework for abilities, attributes and effects — built for Paragon, then Fortnite, with network prediction…
- Gameplay tagsHierarchical name tags (e.g. State.Debuff.Stunned) that label game objects and states without hard-coded enum types or a…
- Gamma correctionThe non-linear curve between stored pixel value and actual brightness — a legacy of cathode ray tubes that turned out to be…
- Gamma GroupAnglo-German group that sold the FinFisher spyware to governments, and whose customer list went public when it was hacked…
- GAN (Generative Adversarial Network)Two neural networks compete: Generator creates fake data, Discriminator tries to spot the fake. Both get better until the…
- GaN-FETGallium-Nitride transistor. Wide-bandgap semiconductor (3.4 eV vs silicon 1.1) → higher switching frequencies, lower losses…
- GandiA French domain registrar with the motto "No Bullshit", which eventually got an owner who saw things differently.
- Gang of Four (GoF)Nickname for the authors of "Design Patterns: Elements of Reusable Object-Oriented Software" (1994) — Gamma, Helm, Johnson…
- Gang punchPunching the same data into an entire deck in one pass — the punched-card era's version of a column default.
- Gap lockA locking mechanism in MySQL/InnoDB that locks the "gap" between index values — not just existing rows, but the range where…
- Gapless playbackPlaying tracks back to back without a single sample of silence between them — taken for granted on CD, surprisingly hard…
- GarageBandApple's simplified music app for Mac, iPhone and iPad — for a lot of people the first DAW they ever opened.
- Garbage Collection (GC)Automatic memory management: the runtime finds and frees memory no longer in use.
- GarboThe University of Vaasa's FTP archive, which supplied the world with DOS software from the Finnish west coast throughout the…
- GarminThe GPS maker that survived the phone eating its car-navigation business by moving to the wrist, the cockpit and the boat.
- GarnetCarnegie Mellon's research toolkit for graphical interfaces in Common Lisp, where layout was built from formulas that…
- GartnerThe analyst firm whose charts decide which vendors even get to bid.
- Gary McGrawAmerican researcher who argued that security has to be built into code, not bolted onto the network afterwards.
- Gary McKinnonThe Scottish sysadmin who went looking for UFO evidence on US military computers and then spent a decade fighting…
- Gary StarkweatherThe optical engineer who suggested in 1969 that a laser be pointed at a copier drum, and was told by management it was a bad…
- GasAnonymous compliments app targeted at teens in the USA. Launched August 2022, top app store within months. Bought by Meta…
- Gas feeWhat it costs to have Ethereum's network perform a computation — the price is set by congestion, not by the transaction's…
- Gaspard de PronyThe engineer who read Adam Smith and concluded that mathematics could be mass-produced the same way pins were.
- Gate-all-around (GAA)A new transistor structure succeeding FinFET, where the gate surrounds the channel on all four sides instead of three. It…
- Gated reverbA big, loud reverb chopped off abruptly by a noise gate, making a drum hit sound enormous yet stop dead.
- GatekeeperOPA-based admission controller for Kubernetes — blocks or mutates resources that violate policies written in Rego.
- GatewayThe device a packet is sent to when its destination is outside the local network — usually the router.
- Gateway 2000Mail-order PCs from an Iowa farm, famous for shipping in black-and-white spotted boxes that looked like cows.
- Gateway APINew K8s standard for traffic routing — successor to Ingress, designed for modern needs.
- Gateway load balancing (GLBP)A first-hop redundancy variant (Cisco GLBP) where several gateways are active at once and share the traffic load — unlike…
- GatsbyA React-based site generator from 2015 by Kyle Mathews. For a few years it was the way to build a fast website with React…
- Gaussian splatting (3DGS)A technique for building a photorealistic 3D scene from ordinary photographs and rendering it in real time. Presented at…
- Gavin LoweComputer scientist who in 1995 found a man-in-the-middle attack in an authentication protocol that had gone unchallenged for…
- GBS formatA file format that captures the Game Boy's sound chip so a game's music can play standalone, without the whole ROM.
- GCC (GNU Compiler Collection)GNU's reference compiler suite — Richard Stallman, 1987. Supports C, C++, Objective-C, Fortran, Ada, D, Go. Compiles the…
- GCM-SIVGCM-SIV is an AEAD mode that survives someone reusing a nonce, a property you hope never to need and are glad to have.
- GConfGNOME 2's settings database, a hierarchy of typed keys behind a daemon, which made programs react to changes instantly and…
- GcoreA CDN born to stream tanks that later discovered the GPU cloud.
- GCR (group coded recording)An encoding that packs data bits into longer code groups so the tape or floppy never loses its clock — the home computer's…
- GDB (GNU Debugger)The Unix world's standard debugger, originally written by Richard Stallman in 1986. Steps through programs, sets…
- GDDR6 (Graphics DDR 6)High-speed RAM for consumer GPUs — wider bus and higher clock than ordinary DDR.
- GDDR6XA high-speed graphics memory (Micron + Nvidia) that uses PAM4 signaling to pack more data per cycle than regular GDDR6. It…
- GDDR7Graphics DDR generation 7. 28-32 Gb/s per pin (vs GDDR6's 18). PAM3 signaling (3 levels instead of NRZ's 2). Standard on…
- GDI (Graphics Device Interface)Windows' drawing layer since 1985: the same calls for lines, text and bitmaps whether the target is the screen, a printer or…
- GDI printerA cheap printer with no page description language or processor of its own — the computer's Windows driver does all the work…
- GDKThe layer of GTK that talks to the window system, so the widgets above it need not know whether they sit on X11, Wayland…
- GDMGNOME's display manager since 1998, rewritten in 2007 to loud protest and, since GNOME 3.6, a GNOME Shell in disguise.
- GDPR (General Data Protection Regulation)The EU's data protection regulation from 2018 — strong, with steep penalties (4% of global revenue).
- GDScriptGodot's in-house scripting language: Python's indentation, with semantics built around the engine's nodes and signals.
- Gearbox SoftwareThe Texas studio that started as a Valve subcontractor and became known for Borderlands – and for finally shipping Duke…
- Geffe generatorThree LFSRs combined through a multiplexer-like switch, which still leaks information about two of them.
- GeheimschreiberGermany's "secret teleprinter" — an inline cipher telex that the Swedes read for years and the British called Sturgeon.
- GEMDigital Research's 1985 graphical desktop, which looked too much like the Macintosh for Apple's liking.
- GEM AESThe half of GEM that handled windows, menus, dialogs and events — sitting on top of the drawing layer VDI, and in ROM on…
- GEM VDIThe drawing layer beneath GEM: a device-independent graphics API built around "workstations" for screen, printer and…
- GemaltoThe world's largest SIM card maker, and for exactly that reason an obvious target for spy agencies.
- Gemini (Google)Google's frontier LLM family — Google DeepMind, launched December 2023. Natively multimodal (text + image + audio + video).
- Gemini FlashGoogle's fast + cheap tier Gemini model. Launched May 2024 (1.5 Flash), 2.0 Flash Dec 2024, 2.5 Flash 2025. 1M token…
- Gemini ProGoogle's flagship LLM family — successor to PaLM/Bard. Multimodal from the ground up, million-token context windows.
- GemmaGoogle's family of open-weights models — "little siblings" of Gemini sharing the same research lineage but with trade-offs…
- GemStone IIISimutronics' text role-playing game on GEnie — a commercial MUD billed by the hour that is still running today.
- Gen DigitalThe holding pen of consumer security, where Norton, Avast and AVG now share an owner.
- Genaille–Lucas rulersNumbered rods where printed arrows led the eye straight to the product — Napier's bones without the mental carry.
- Gene KimWrote the Tripwire file integrity checker as a student, then became the DevOps movement's storyteller.
- Gene SpaffordAmerican computer scientist, universally "Spaf", who kept Usenet's group lists in order before becoming one of the leading…
- General MagicThe Apple spin-off that built the smartphone fifteen years too early, and failed so thoroughly that its alumni went on to…
- General MIDIThe addendum to MIDI that fixed which instrument each program number should be, so a song sounds roughly the same on any…
- Generated columnA column whose value the database computes from other columns in the same row. Cannot be written to, cannot drift out of…
- Generational indexA reference that packs an array index together with a generation counter, so an old handle pointing at a reused slot can be…
- Generic Event Extension (XGE)The X11 extension that made events longer than 32 bytes possible, so XInput 2 could report pressure, tilt and fingers…
- Generic programmingWriting code that works for many types without losing type checking. List<T>, Vec<T>, HashMap<K, V>.
- GenericsParametric polymorphism — functions/types parameterized over types. Vec<T> works for T = String, T = i32, T = whatever…
- GeneveGeneric Network Virtualization Encapsulation — a flexible overlay tunneling protocol (RFC 8926) meant to succeed VXLAN. It…
- Genevieve GrotjanAmerican mathematician whose discovery on 20 September 1940 broke the Japanese PURPLE machine.
- GEnieGeneral Electric's online service, built on mainframe time that would otherwise have sat idle every evening.
- GenlockThe technique of locking a computer's video signal to an external source so graphics can be laid over moving footage.
- GeoCitiesFree web hosting that gave millions of people their first homepage, organised into themed "neighborhoods" with street…
- GeoclipmapRenders vast terrain as a set of nested grids around the camera, each outer ring half as dense — level of detail that falls…
- GeocodingTurning an address into coordinates — and reverse geocoding is the same trip in the other direction.
- Geoffrey HintonStuck with neural networks through the decades when the field regarded them as a dead end — and turned out to be right.
- GeoJSONA JSON format for geographic data, standardized in RFC 7946 (2016). The obvious way to move map data between a server and a…
- Geometry (X11)The string of the form 80x24+10+10 that every X program since the 1980s has understood as "this big, and there", with a…
- Geometry management (Xt)The X Toolkit's rules for who decides a widget's size and position: the child asks, the parent decides, and the shell at the…
- Geometry shaderAn optional pipeline stage that operates on whole primitives and can create or discard geometry on its way through the…
- GeomipmappingTreats a terrain's height field like a mipmapped texture: fixed tiles, each with several precomputed levels of detail chosen…
- GeomorphingA smooth transition between two terrain LOD levels by gradually interpolating vertex heights, so the detail swap does not…
- Georg ScheutzThe Stockholm lawyer who built the difference engine Babbage never finished, and sold it to an observatory in New York.
- George BlakleyThe mathematician who invented secret sharing the same year as Adi Shamir — and watched the other version become the one…
- George BooleWrote an algebra of human reasoning and died without the faintest idea that it would become the design method for electrical…
- George DanezisThe anonymity researcher who has spent two decades asking how much metadata gives away when the content is encrypted.
- George HotzHacker who unlocked the first iPhone as a teenager and was later sued by Sony over a signing key.
- George KurtzSecurity veteran who founded CrowdStrike in 2011 to replace heavy antivirus with a lightweight cloud agent — and in 2024 led…
- George StibitzThe mathematician who built a binary adder on his kitchen table out of scrapped telephone relays and a tobacco tin, and…
- Georgi GuninskiBulgarian researcher who, around the turn of the millennium, found browser holes at a pace that made the vendors look…
- GEOSA 1986 graphical operating system for the Commodore 64 that gave the 8-bit machine windows, a mouse pointer and WYSIWYG.
- Gerald CombsThe network engineer who wrote Ethereal in 1998 because he couldn't afford a commercial protocol analyzer, and who still…
- Gerber formatThe file format every board house on earth expects, named after the machine it was originally invented to drive.
- Gerolamo CardanoGerolamo Cardano was an Italian physician and mathematician who described the Cardan grille, one of the earliest…
- Gerstner wavesA wave model in which each water particle moves in a circle, giving sharp crests and broad troughs instead of a smooth sine…
- Gertrude BlanchTook a doctorate in mathematics at 38 after fourteen years as a clerk, then ran the human computing operation that…
- GetStreamAPI service that delivers ready-made activity feeds and chat so developers don't rebuild the same social features from…
- GGI (General Graphics Interface)The 1990s attempt to give Linux a graphics layer in the kernel and one library on top, so X, the console and games would…
- GGPORollback netcode middleware that made online play of 2D fighting games feel like playing on the same couch.
- GGUFA file format (successor to GGML) for packaging quantized language models in a single file, designed for llama.cpp and local…
- GHASHThe universal hash inside GCM, which turns ciphertext into a polynomial and evaluates it at a secret point.
- GhostOpen-source blogging platform + newsletter — "WordPress for people who hate WordPress". Run by a non-profit, focused on…
- Ghost in the WiresKevin Mitnick's 2011 memoir — the story of his years on the run, told from his side.
- Ghost replayA translucent copy of an earlier lap that races alongside the player in time trials, unable to collide with anything.
- GhostscriptA free interpreter for PostScript and PDF that renders pages to screen, image or printer — the invisible engine behind most…
- Giambattista della PortaNeapolitan natural philosopher whose 1563 treatise described a polyalphabetic cipher where the key letter selects one of…
- GibsThe torn-off body parts and bloody debris flung out when a game object is destroyed — short for "giblets".
- GIF (Graphics Interchange Format)CompuServe, 1987. 8-bit (256 colors), lossless, supports animation. Patent on LZW compression led to PNG's creation in 1996…
- GIF shareEmbedded animated GIFs as reaction or comment. Tenor and Giphy are the dominant GIF libraries. Tenor was acquired by Google…
- Gigabyte TechnologyThe motherboard maker whose name always needs a footnote: the company, not the unit.
- GiganewsOne of the big commercial Usenet providers — the kind of company that took over once ISPs stopped running their own news…
- GigaSamplerThe 1998 software sampler that streamed audio straight from the hard disk, making instrument libraries larger than the…
- GigascreenA Spectrum trick that swaps two images every frame so the eye blends them into more perceived colours.
- GIGO (Garbage In, Garbage Out)Computer science fundamental: bad input → bad output, no matter how smart the algorithm is.
- Gil ShwedIsraeli entrepreneur who founded Check Point in 1993 and turned the firewall into something you could buy off the shelf.
- Gilbert VernamThe AT&T engineer who in 1917 patented the XOR encryption that would become the only provably unbreakable cipher.
- Gilles BrassardThe Montréal cryptographer who took Stephen Wiesner's quantum money and, with Charles Bennett, turned it into a usable key…
- Gilles Van AsscheBelgian cryptographer and one quarter of the Keccak team, whose sponge construction won NIST's hash competition and became…
- Gimbal lockThe loss of one rotational degree of freedom when two of three rotation axes line up, so the object can no longer be turned…
- GIMP (GNU Image Manipulation Program)The famous open-source alternative to Photoshop — frustrating UI, powerful under the hood. 2.10 since 2018, 3.0 finally…
- GIN indexGeneralized Inverted Index in PostgreSQL — an inverted index optimized for values that contain multiple components: arrays…
- Giovan Battista BellasoItalian cryptographer who described the keyword-driven polyalphabetic cipher in 1553, a method that later took Vigenère's…
- Giovanni PoleniThe Padua professor who built the first pinwheel machine in 1709, drove it with a falling weight — and then smashed it in a…
- Giovanni VignaItalian professor who turned a CTF team into a research institution.
- GIS (Geographic Information System)Systems for storing, analysing and visualising data that has a location.
- GiST indexGeneralized Search Tree — an extensible index type in PostgreSQL. Powers the geometric indexes (PostGIS), full-text search…
- GitThe dominant version control system — tracks every change in code over time.
- git bisectBinary search through commit history to find the commit that introduced a bug. git bisect start, mark good/bad, repeat — git…
- git cherry-pickCopies a single commit from one branch to another. Classic use: backport a bugfix from main into a release branch.
- git fsmonitorBuilt-in filesystem monitor (git 2.37+, 2022) — speeds up git status on huge repos by listening for FS changes instead of…
- Git LFSLarge File Storage — stores big files (videos, ML models, PSDs) outside git, with text pointer-file in git. Maintained by…
- git rebaseRewrite Git history — move commits, combine them, change order.
- git reflogLocal log of every change to HEAD (and other refs) — your safety net when you've done something stupid like git reset --hard.
- git sparse-checkoutCheck out only part of a huge repo into your worktree — handy in monorepos where you only work on one team's directory.
- git stashTemporarily save half-finished work without committing — for quickly switching branches.
- git submoduleA repo inside a repo — points to a specific commit in another git repo. Widely hated but no one's come up with a cleanly…
- git worktreeMultiple checkouts of the same repo in different directories — without cloning twice. git worktree add ../hotfix release-1.2.
- GiteaA lightweight self-hosted Git forge in a single binary — GitHub's whole workflow in a can you run yourself.
- GitHubWorld's largest code hosting platform — 100M+ developers. Tom Preston-Werner, Chris Wanstrath, PJ Hyett, 2008. Microsoft…
- GitHub ActionsGitHub's built-in CI/CD — YAML workflows in .github/workflows/. Launched November 2019, became the dominant CI for open…
- GitHub CopilotGitHub's AI completion tool — suggests code in your IDE based on file context and comments. Originally trained on OpenAI…
- GitHub DiscussionsA forum feature inside GitHub repositories, launched in 2020. It exists to separate conversation from work — issues should…
- GitLabGit-based DevOps platform — repo, CI/CD, code review, issue tracking, container registry, all in one. Self-hosted (free…
- GitleaksCLI that scans git history and pre-commit staging for leaked secrets — API keys, JWTs, SSH private keys, plaintext passwords.
- GitOpsOperations philosophy where the entire infrastructure is described in Git and an operator keeps reality in sync.
- GitOps reconcileThe core loop of GitOps: an agent continuously compares the cluster's ACTUAL state with the DESIRED state (defined…
- GitpodOne of the first services to move the whole development environment into the cloud — click a link, get a ready-made editor…
- GJK algorithmA method that decides whether two convex bodies collide by hunting for the origin inside their Minkowski difference.
- GladeGTK's graphical interface builder from 1998, where you drag buttons and boxes into a window and get the description back as…
- GlamorThe X.Org module that draws 2D through OpenGL, so a graphics driver needs no acceleration code of its own at all.
- Glass substrateThe disc a hard drive's magnetic film is deposited on — glass instead of aluminium gives flatter, stiffer platters that…
- GLBPGateway Load Balancing Protocol — Cisco proprietary. Distinct from HSRP/VRRP: GLBP load-balances traffic across multiple…
- Glenn DurfeeCryptanalyst whose name is welded to Dan Boneh's in the attack that recovers a too-small private RSA exponent from the…
- Glenn GreenwaldThe journalist who broke the first Snowden stories in 2013, after initially ignoring the source because he couldn't be…
- Glenz vectorA filled 3D vector object whose faces are drawn transparent, so the back of the shape shines through like glass.
- glibc (GNU C Library)GNU's libc implementation — de-facto standard in nearly all Linux distros. Big, complex, backward-compatible far into the…
- Glide heightThe certification fly height at which a test head is flown to catch asperities before a real head does.
- glitch-socA community-driven Mastodon fork (officially "glitch-soc") that adds features the main project is cautious about — an…
- GlobPattern matching for filenames: *.txt, photo_?.jpg, src/**/*.js.
- Global CrossingA company that laid fibre under the oceans for a traffic boom that did arrive – just a decade too late for its shareholders.
- Global illuminationSimulating indirect light — light that bounces between surfaces and bleeds colour onto them — and not just the direct light…
- Global secondary index (GSI)A secondary index in a distributed database that is partitioned independently of the main data — on its own index value. A…
- Global variableVariable visible throughout the program. Classic anti-pattern in modern programming — breaks encapsulation, makes testing +…
- GlobalFoundries (GF)Third largest foundry — spun out from AMD 2009 with Abu Dhabi's Mubadala as owner. Abandoned the advanced node race in 2018…
- GlobalSignA Belgian certificate authority from the web's early days, now Japanese-owned and one of the roots browsers trust without…
- glTFKhronos's open delivery format for 3D models, built to load fast rather than to be edited.
- GlusterFSScale-out distributed filesystem — aggregate a server's local disks into a shared POSIX namespace. Maintenance in recent…
- GLXThe glue between OpenGL and X11 — the reason a 3D program gets a window to draw into at all.
- GMACGCM used purely for authentication, with no encryption of the data itself.
- GmailGoogle's email service — when it launched on 1 April 2004 with 1 GB of storage everyone assumed it was an April Fools' joke…
- gmc (GNOME Midnight Commander)GNOME 1's file manager and desktop icons: the text-mode Midnight Commander with a GTK window bolted on, built in a hurry and…
- GMCPGeneric MUD Communication Protocol — an invisible side channel next to the text where the server ships game state as JSON.
- GMR headA read head built on giant magnetoresistance — the 1988 discovery that let disk capacity explode through the late 1990s and…
- gMSA (Group Managed Service Account)A service account whose password is generated and rotated by the domain controllers themselves, and retrieved automatically…
- GN (Generate Ninja)Meta-build for Chromium — generates Ninja files. Replaced GYP 2014. Faster + cleaner build configs.
- GNOMEThe free desktop environment launched in 1997 because KDE was built on a toolkit whose licence wasn't free.
- GNOME PanelThe panel of GNOME 1 and 2: the strip of menus, window list and applets that GNOME 3 abolished and two forks kept alive.
- GNOME ShellGNOME 3's desktop shell from 2011, written in JavaScript on top of Mutter, which traded the panel and window list for an…
- GNUThe project that set out to build a free Unix-like system — and succeeded at everything except the kernel.
- GNU RocketA sync tool for demos that drives cameras, colours and effects in time with the music through a tracker-style interface.
- GNU SocialAn early federated microblogging platform (rooted in StatusNet, 2008) that was the Fediverse before Mastodon existed. It…
- gnu.*The Usenet hierarchy for the GNU Project, in which every group was gatewayed both ways to a Free Software Foundation mailing…
- GnusThe newsreader that lives inside Emacs and gradually became a reader for almost anything that can be read.
- GNUstepA free reimplementation of OpenStep, begun in the mid-1990s and still going, meant to bring NeXT's frameworks to Unix.
- Go (Golang)Google's systems language — Rob Pike, Ken Thompson, Robert Griesemer (2009). Designed for low-ceremony concurrency, fast…
- GOAPA planner that assembles a chain of actions at runtime to reach a goal, instead of following a pre-authored behavior.
- GoatTrackerThe cross-platform tracker that lets you write genuine C64 music on a modern machine — SID sound with no real Commodore in…
- God raysVisible shafts of light streaming through clouds, windows or foliage as light scatters off particles in the air — almost…
- GoDaddyThe world's biggest domain registrar, better known for its ads than for anything it built.
- Gödel's incompleteness theoremsThe 1931 proof that any sufficiently powerful formal system holds truths it cannot prove — and cannot even certify its own…
- GodotOpen-source game engine — explosive growth after the 2023 Unity pricing scandal. Own scripting language GDScript…
- Godwin's law"As an online discussion grows longer, the probability of a comparison involving Hitler or Nazis approaches one." Formulated…
- Goertzel algorithmA way to compute one frequency component of a signal, cheaper than a full FFT when you only care about a handful of tones.
- GOG.comCD Projekt's store, which sells games entirely without copy protection and rescues old titles from vanishing.
- GojekIndonesian superapp — started as a motorcycle-taxi (ojek) call centre, pivoted to app in 2015. Today food, money, massage…
- GoldEDThe sysop's own FidoNet mail reader — a text-mode editor that read the message base straight off the disk rather than…
- Golden imageA pre-built, pre-configured, and hardened template image (for a VM or container) that all instances are started from…
- Golden TicketForge any Kerberos TGT in a Windows domain — total domain compromise if the attacker has the krbtgt hash.
- GoldSrcValve's first game engine — a heavily rebuilt Quake engine that powered Half-Life in 1998 and laid the groundwork for…
- Goldwasser–Micali cryptosystemThe first probabilistic public-key encryption scheme, and the first proven semantically secure.
- GongRecords and transcribes sales calls, then lets language models read out which deals are actually moving and why.
- GoniometerA stereo meter that plots the left channel against the right as a shape, so width, balance and phase problems can be seen…
- GoodreadsThe social network for readers — log books, rate, review, "reading challenge" counter. Bought by Amazon in 2013 and has…
- GoogleWon the search market by ranking pages according to who links to them — and built an advertising machine on top.
- Google Apps ScriptJavaScript running inside Google Workspace — the macro language holding together half the world's internal office processes.
- Google ChromeGoogle's browser, released 2008. Built on Chromium (open source) + Blink (rendering, forked from WebKit 2013) + V8 (JS)…
- Google Cloud (GCP, Google Cloud Platform)Google's cloud — ~12 % market share. Strong in data (BigQuery), AI/ML (Vertex AI), and containers (Kubernetes was invented…
- Google Cloud DataflowGoogle's managed runner for Apache Beam pipelines — the same code for batch and streaming, with no cluster to babysit.
- Google Cloud PrintGoogle's 2010–2020 cloud service that let any device print to any printer by routing the job through Google's servers.
- Google DocsReal-time collaborative word processing in the browser — built on Writely (acquired 2006). Defined the whole "multiplayer…
- Google DriveGoogle's cloud storage + file collaboration. Launched April 2012 (after Google Docs existed since 2006). Drives Google…
- Google FontsGoogle's free open-source font library. Launched 2010. ~1500 font families. SIL OFL license (Open Font License). Default…
- Google MeetGoogle's video conferencing service — successor to Hangouts Meet and Duo, made free during COVID 2020 to siphon Zoom's…
- Google PlayAndroid's principal store — more open than the App Store, but in practice just as hard to avoid.
- GopherThe web's forgotten competitor — a menu-based document system from 1991 that lost on licensing terms.
- Gopher+The extension meant to give Gopher metadata, formats and forms — arriving just as users were leaving for the web.
- GophermapThe file that describes a Gopher menu: one line per item, with a type character, display text, selector, host and port…
- GoProThe action camera that turned first-person footage of extreme sports into a genre of its own — and a company that never…
- Gordon LyonThe author of Nmap, the tool that has made port scanning step one of almost every security assessment since 1997.
- Gordon MooreWrote a 1965 article containing an observation about transistor density that became the industry's timetable for half a…
- Gordon WelchmanThe man whose addition made the Bombe usable in practice — and who lost his security clearance forty years later for saying…
- GORMThe most popular Go ORM — chained API (db.Where("age > ?", 18).Find(&users)), auto-migration, hooks, transactions.
- GOSIPGovernment OSI Profile — governments' attempt to mandate the OSI protocols into existence and retire TCP/IP through…
- Gossip protocolEpidemic-style information spreading: each node randomly picks a few peers and shares its state — after O(log N) rounds…
- Gossip protocol (DB)A decentralized way for nodes in a cluster to spread information (which nodes exist, their status, ring topology) by…
- GOST 28147-89The Soviet answer to DES: a block cipher with a 64-bit block, a 256-bit key and secret S-boxes.
- GotekA small unit that replaces a floppy drive with a USB stick full of disk images.
- GoToSocialLightweight Fediverse server software written in Go, designed to run on minimal hardware (a Raspberry Pi is enough). It…
- Gottfried LeibnizThe philosopher who wanted disagreements settled by the words "let us calculate", and who happened to leave behind both the…
- Gouraud shadingA way to smooth out faceted 3D surfaces by interpolating light values across the vertices instead of shading each polygon…
- Government Code and Cypher SchoolThe British government's codebreaking agency, founded in 1919, moved to Bletchley Park and renamed GCHQ in 1946.
- GPG (GNU Privacy Guard)Open source implementation of PGP — for encrypting files, signing commits, verifying packages.
- GPIBHewlett-Packard's 1960s parallel instrument bus, standardised as IEEE-488, which among other things connected plotters and…
- GPIO (General Purpose Input/Output)General-purpose pins on microcontrollers and small computers (Raspberry Pi, Arduino).
- GPL (GNU General Public License)The Free Software Foundation's copyleft license. Richard Stallman, 1989. Requires derivative works to be distributed under…
- GPONGigabit Passive Optical Network — the dominant technology for fiber broadband to the home (FTTH). One fiber from the…
- GPP passwords (cpassword)Microsoft let administrators set local passwords via group policy, encrypted with AES-256 — and published the key in its own…
- GPQAGraduate-Level Google-Proof Q&A — benchmark of 448 PhD-level questions in biology/physics/chemistry. Created in 2023 by…
- GPS (Global Positioning System)US satellite navigation. 31 satellites in medium Earth orbit. Receiver computes position via time signals from ≥4 satellites…
- GPT (Generative Pre-trained Transformer)OpenAI's LLM family — GPT-1 (2018) → GPT-2 (2019) → GPT-3 (2020) → GPT-4 (2023) → GPT-4o (2024) → o1/o3 (reasoning…
- GPT-4OpenAI's flagship model March 2023 → 2024. Dramatically smarter than GPT-3.5. Laid the foundation for the "AI replacing…
- GPT-4oOpenAI's first "omni-modal" model — text, audio, image in the same network. Real-time voice conversation with ~320 ms…
- GPTQPost-training quantisation for LLMs down to 3–4 bits via approximated Hessian-based error compensation per layer.
- GPU (Graphics Processing Unit)A processor specialised in doing many small mathematical operations in parallel.
- GPU clusterHundreds to tens of thousands of GPUs interconnected for large-scale AI training. Hyperscaler scale: Meta 24k H100, xAI 100k…
- GPU coolingThermal management for datacenter GPU. H100 (700W per GPU) + 8-GPU server = 5.6 kW in 4U chassis → traditional air cooling…
- GPU driverDrivers for graphics cards — translate API calls (OpenGL, Vulkan, DirectX, Metal) into GPU commands. Notoriously complex…
- GPU instancingDrawing many copies of the same mesh in a single call by handing the GPU a small table of per-instance data instead of…
- GPU particlesParticle simulation that runs entirely on the graphics card, so millions of particles can update without burdening the CPU…
- GPU readbackCopying data from the GPU back to the CPU — trivial to write, notorious for stalling the pipeline.
- GPU-driven renderingA rendering architecture where the GPU culls the scene and builds its own draw lists with compute passes and indirect calls…
- GQA (Grouped-Query Attention)A compromise between multi-head attention (MHA, one KV per head) and multi-query attention (MQA, one KV total) — multiple…
- GraalVMOracle Labs's JVM alternative. Launched 2018. Two main features: Native Image (AOT-compile Java to native binary) + polyglot…
- GrabSoutheast Asia's superapp — taxis + food + bank + delivery. Bought Uber's SEA business 2018. Public via SPAC 2021 (largest…
- Grab (X11)An X client claiming all pointer or keyboard input for itself, regardless of which window has focus.
- Grace Hopper (person)The rear admiral who pushed through the idea that programs could be written in something resembling English — and built the…
- Graceful restartA mechanism that lets a router restart its routing process without traffic stopping, by getting the neighbours to agree to…
- Graceful shutdownEnd a process cleanly: stop accepting new requests, wait for in-flight ones, release locks, flush buffers, close…
- Gradient accumulationRunning several small batches and summing their gradients before the optimizer takes a step, to simulate a batch size that…
- Gradient checkpointingSave memory during training by recomputing parts of the forward pass instead of storing all intermediates.
- Gradient clippingPutting a ceiling on how large a training step may be, so a single anomalous batch doesn't destroy a model that took weeks…
- Gradient descentThe optimisation algorithm that trains almost every ML model — take small steps in the direction that reduces error most.
- GradleThe JVM build system that replaced Ant/Maven — Hans Dockter, 2007. Default build for Android (since 2013). DSL in Groovy or…
- GrafanaThe dashboard tool for visualising metrics and logs — talks to Prometheus, Loki, InfluxDB, etc.
- GrafX2A 256-colour pixel art editor written for DOS in 1996, essentially an answer to "why is there no Deluxe Paint on the PC?".
- Graham CluleyThe antivirus veteran who became the security industry's most effective explainer.
- Grain (cipher)A stream cipher from the eSTREAM project that combines a linear and a nonlinear shift register.
- GrammarlyBrowser extension that checks grammar, tone and style in real time — 30M+ daily users. A Ukrainian startup that survived the…
- Granny 3DRAD Game Tools' middleware for exporting, storing and playing back animated 3D models — its .gr2 format turns up in more…
- Granular mediaThe recording layer of a hard disk, built from thousands of microscopic magnetic grains each walled off from its neighbours…
- Granular synthesisSound chopped into thousands of millisecond-long grains, then scattered back out in a new order, density and pitch.
- GraphNodes + edges. The most versatile data structure — model social networks, road networks, dependencies, neural networks…
- Graph databaseDatabase optimized for graph data — nodes with relationships. Queries via path traversal instead of joins. Strong where…
- Graph of Thoughts (GoT)Generalises Tree of Thoughts to a DAG — thoughts can merge, aggregate, refine each other. ETH Zürich paper August 2023.
- Graph theoryMathematical study of graphs (nodes + edges). Leonhard Euler founded it in 1736 with the Königsberg seven bridges problem…
- GraphcoreBritish AI chip startup that designed its own processor architecture, the IPU, and became Europe's great hope against Nvidia…
- Graphics context (X11)A bundle of drawing settings kept on the server, so that every line doesn't have to ship its own colour across the network.
- GraphicsExpose and NoExposeThe events that tell a client whether a copy inside the X server worked, or left holes it has to paint itself.
- GraphQLAn API style where the client sends a query describing exactly which fields it wants back.
- GraphQL SubscriptionsGraphQL's third operation type — push of real-time data from server to client via WebSocket or SSE. Alongside queries and…
- GraphvizThe tool that draws graphs for you. You describe nodes and edges in the DOT language and a layout engine works out where…
- Gratuitous ARPAn ARP packet a host sends unprompted to update neighbors' ARP caches. Format: an ARP request where source and target IP are…
- Gravis UltraSoundThe sound card the demoscene adored — wavetable with its own sample RAM that mixed 32 channels in hardware.
- Gravity (X11)X11's rules for what stays where when a window changes size.
- GravityNotifyThe X11 event for subwindows the server moved on its own because their parent changed size.
- Gray codeA binary sequence in which only one bit changes between successive values — so a reading can never get stuck mid-jump…
- GrayshiftThe Atlanta company behind GrayKey, a small grey box that police plug iPhones into to crack the passcode.
- GRE (Generic Routing Encapsulation)A tunnelling protocol from Cisco, standardized in RFC 2784. It wraps an arbitrary protocol inside an IP packet and forwards…
- GRE tunnelGeneric Routing Encapsulation — Cisco-developed point-to-point tunneling. RFC 2784. Encapsulates arbitrary network traffic…
- GreaseweazleA cheap, open USB board that reads and writes floppies at the flux level – a KryoFlux for people who'd rather not pay for a…
- Great CipherLouis XIV's diplomatic cipher, designed by the father-and-son team of Rossignols, which went unread for roughly two…
- Great RenamingThe 1987 reorganisation of Usenet, which sorted the flat net.* groups into topic hierarchies like comp, sci and rec — and…
- Greedy algorithmStrategy: make the locally best choice at every step and hope the result is globally optimal. Not always — but often enough…
- Greedy decodingLLM sampling strategy: always pick the token with the highest probability. Equivalent to temperature=0 + top_k=1…
- Greedy meshingAn algorithm that collapses a voxel chunk's exposed faces into as few large rectangles as possible, slashing the triangle…
- Green bar paperThe green-and-white striped continuous-form paper that computer output came on for decades.
- Green Card spamThe ad two lawyers posted to thousands of newsgroups in 1994, turning commercial spam into a business model.
- Green Hills SoftwareUS firm behind INTEGRITY — a safety-critical real-time operating system for avionics and defence.
- Green screen (TikTok)A TikTok effect that puts an image, screenshot, or video behind you while you talk — like a weather presenter's green…
- Greenfield projectA new project without existing code to deal with. Free to choose tech, architecture, patterns. Opposite: brownfield (adding…
- GreenplumMPP (Massively Parallel Processing) data warehouse built as PostgreSQL fork. EMC-acquired 2010, Pivotal spinoff, VMware…
- GreetingsThe shout-outs demos and cracktros wove into their scrolltexts — the scene's social currency, aimed at friends and rivals…
- GreetzLeet-spelled greetings in cracktros, intros, and NFO files — name-drops to friendly groups and individuals, the scene's…
- Greg HoglundAmerican researcher who turned Windows rootkits into a public field of study, and whose company later became Anonymous's…
- GremlinThe graph query language of Apache TinkerPop — describing a walk through nodes and edges, one step at a time.
- grepUnix tool for regex-based searching in text. Ken Thompson, 1973. Name from the ed command g/re/p = "Globally find Regular…
- GrexA member-run public-access Unix machine in Ann Arbor, where anyone could get a free shell account and join the conferences.
- Griffin–Lim algorithmAn iterative method for turning a magnitude-only spectrogram back into audio by guessing the phase until it hangs together.
- Grit wheelHP's paper drive for plotters, where small sandpaper-coated wheels grip the sheet at the edge and rock it back and forth…
- GrokxAI's LLM. Elon Musk's AI company, founded 2023 after the split with OpenAI. Integrated into X (formerly Twitter) for…
- Gromark cipherA running-key cipher whose key stream grows out of a short five-digit primer by addition modulo 10.
- Gronsfeld cipherVigenère with a string of digits as the key – and therefore only ten possible shifts per position.
- GroovyA dynamic language for the JVM, started in 2003 by James Strachan. Almost all valid Java is also valid Groovy, but with…
- GroqHardware startup with an "LPU" (Language Processing Unit) — chip designed specifically for LLM inference, 5–10× faster than…
- Ground loopTwo devices grounded through different paths, with the signal cable between them completing a current loop — and a stubborn…
- Grounding (LLM)LLM feature: connect responses to external data sources (web search, internal docs, knowledge base) with citations. Reduces…
- GROUP BYThe SQL clause that collapses rows sharing a value into one row per group, so aggregate functions like COUNT, SUM and AVG…
- Group call protocolThree topologies for multiple participants: mesh (peer-to-peer between all, max 3-4), MCU (server transcodes and mixes, high…
- Group chat namingThe social (usually jokey) custom of naming and constantly renaming a group chat. A small but culturally loaded phenomenon…
- Group commitOptimization where several simultaneous commits are batched and fsync'd together. An fsync is expensive (5-10 ms on SSD)…
- Group delayHow long a filter holds back each frequency — measured as how quickly the phase turns as frequency changes.
- Group DMA private group chat within a social platform (Instagram, Twitter/X, Discord) — a direct message with several participants…
- Group ReplicationMySQL's built-in solution for synchronous, consensus-based replication — the foundation of InnoDB Cluster. A group of…
- Grouped-query attention (GQA)An attention variant where several query heads share the same set of key/value heads, instead of each having its own. It…
- GROUPING SETSA SQL extension of GROUP BY that lets you compute several different groupings in a single query. Instead of running several…
- Grover's algorithmSearches an unsorted set in the square root of the number of steps rather than half of them — a quadratic gain, not an…
- GrøstlA Danish-designed hash function that reached the SHA-3 final and still never became a standard.
- gRPCGoogle's RPC framework over HTTP/2 — compact binary protocol with strong types (Protobuf).
- GRPO (Group Relative Policy Optimization)DeepSeek's RL algorithm for training reasoning models — cheaper than PPO, eliminates the value model by comparing groups of…
- GRUB (GRand Unified Bootloader)The Linux world's standard boot loader. It loads the kernel and initramfs into memory, passes along kernel parameters and…
- GrubhubUS #3 food delivery app — merged with Seamless 2013, bought by Just Eat Takeaway 2021 for $7.3B, sold to Wonder 2024 for…
- GrundstellungThe Grundstellung was the starting position of the Enigma rotors, part of the daily key and the first step in every…
- GS1The non-profit that governs the barcode standards — EAN, UPC and the GTIN numbers behind almost every item on a shop shelf.
- GSAP (GreenSock Animation Platform)The old, fast animation library for the web. It came out of the Flash era and outlived it. Animates anything with a numeric…
- GSMThe European 2G standard that made mobile telephony global — and gave us the SIM card and SMS.
- GSO / TSOGeneric Segmentation Offload + TCP Segmentation Offload — Linux + NIC features where a large send buffer (64KB) is split…
- GsonGoogle's Java library for turning objects into JSON and back, in two method calls and zero annotations.
- GTAOA screen-space ambient occlusion that was fitted to a path-traced reference so it stops over-darkening creases.
- GTFOBinsThe catalogue of ordinary Unix programs that can be made to spawn a shell. The conclusion is that "you may run find as root"…
- GTID replicationGlobal Transaction Identifier — a system in MySQL where every transaction gets a globally unique ID. It makes replication…
- GTK (GIMP Toolkit)A widget library for graphical interfaces, originally written for the GIMP image editor in 1998 and then split out as its…
- GTSM (Generalized TTL Security Mechanism)A defence exploiting the fact that TTL can only be decremented: send with 255 and require at least 254 back, so only…
- Guard bandThe unused magnetic space between two tracks, there for one reason only: to stop neighbouring tracks from leaking into each…
- Guard patternThe extra bar pairs at the start, middle and end of a UPC or EAN code that tell the scanner where the code begins, splits…
- GuardicoreAn Israeli microsegmentation tool, now Akamai's, that draws firewall rules between individual workloads rather than around…
- GuardrailsProtective layers that prevent the LLM from producing inappropriate output — or accepting inappropriate input.
- Guardrails (AI)Protective layers around an LLM that check and constrain what goes in and comes out — block harmful queries, filter…
- GucciferA Romanian amateur who broke into politicians' email without a single exploit — just by guessing the answers to their…
- Guerilla Open Access ManifestoA short 2008 text signed by Aaron Swartz urging anyone with access to paywalled research to share it.
- Guess-and-determine attackAn attack that guesses part of a cipher's internal state and works out the rest from linear or simple relations.
- GUI (graphical user interface)The interface where you point at things on a screen instead of typing what they are called.
- Guided decodingForcing a language model to produce output that follows a schema by masking out, at every step, every token that would…
- Guido BertoniItalian cryptographer and one of the four designers of Keccak, the hash function that won the SHA-3 competition.
- Guido van RossumStarted writing Python over a Christmas break in 1989 as a hobby project — and then steered the language for three decades…
- Guitar ProA French tablature editor whose file format became the guitar world's de facto standard for sharing parts.
- GumroadPlatform for selling digital products (e-books, Notion templates, Lightroom presets, courses) — minimal setup.
- GumtreeBritish classifieds site — eBay bought it in 2005, sold to Adevinta in 2020 (Blocket's parent). Australia + South Africa…
- Gunter's scaleA logarithmic scale on a ruler that turned multiplication into adding two lengths with a pair of dividers — the slide rule…
- Guru MeditationThe Amiga's crash screen — a flashing red box with two hex numbers, named after an in-house yoga joke.
- Gus SimmonsSandia mathematician who discovered that a digital signature can smuggle out hidden messages nobody notices.
- GutenprintAn open driver suite that makes hundreds of inkjet and laser printers work on Linux, macOS and other Unix systems.
- Guy RothblumTheorist whose name sits on two of the most-cited results to come out of both Goldwasser's and Dwork's circles.
- gVisorGoogle's user-space kernel — intercepts syscalls from the container and reimplements them in a sandboxed Go process instead…
- GWMThe Generic Window Manager, Bull's programmable window manager from 1989, in which frames, menus and behaviour were written…
- Gynvael ColdwindPolish security researcher and CTF veteran, co-founder of Dragon Sector and one of the people who showed just how broken a…
- gzipThe compression algorithm that's been the web's standard for 25 years — shrinks HTML/CSS/JS by ~70%.
- Nvidia Grace Hopper (GH200)Nvidia superchip — Grace ARM CPU (72 Neoverse V2 cores) + Hopper H100 GPU on the same board, connected via 900 GB/s…
H
- :has() selectorCSS selector that matches an element's parent based on its children — the long-awaited "parent selector".
- .htaccessApache's per-directory configuration file — where redirects, password protection and rewrite rules go when you don't own the…
- Apache HadoopOpen source framework for distributed storage + compute on commodity hardware. Doug Cutting, Yahoo, 2006. Based on Google's…
- Apache HiveSQL layer on top of Hadoop/HDFS — Facebook, 2008. Helped thousands of analysts leave MapReduce and write SQL instead.
- Apache HudiLakehouse table format from Uber (2017) — first to ship upserts, incremental queries and "time travel" on Parquet data…
- Claude HaikuAnthropic's small + fast tier. Haiku 4.5 (October 2025). $1/M input, $5/M output. Sub-second latency. Use cases: real-time…
- Consistent hash ringDistribute keys across N nodes so that adding/removing a node only moves 1/N of the keys — instead of all of them with a…
- H. D. MooreCreator of Metasploit, the framework that turned exploits into interchangeable modules rather than loose scripts on obscure…
- H.264The video codec that became universal — twenty years old, worse compression than anything newer, and still what you pick…
- H.265 (HEVC)The successor to H.264 that halved the bitrate — and then tripped over its own licensing.
- H2O.aiOpen-source ML platform known for AutoML — and for a co-founder who wrote the JVM's JIT compiler.
- Haas effectHearing lets whichever sound arrives first decide the direction, even when a copy arriving a few milliseconds later is…
- Habana LabsIsraeli AI-chip firm behind the Gaudi accelerators, bought by Intel in 2019 as its answer to Nvidia's grip on training.
- HabitatLucasfilm's graphical online world for the Commodore 64, where the players taught the designers that a virtual world can't…
- Hacker News (HN, news.ycombinator.com)Orange tech forum run by Y Combinator — one of the few remaining "old internet" places where tech people actually discuss.
- HackerOneThe middleman that turned finding other people's security holes into a job — and got the Pentagon to pay for it.
- Hacking TeamMilan-based vendor of intrusion tools for police and intelligence agencies, until it got hacked itself and had its entire…
- Hadamard gateThe gate that takes a qubit from a definite value into even superposition — the opening move of nearly every quantum…
- HafniumMicrosoft's name for a state-sponsored APT, attributed to China — discovered as the actor behind the ProxyLogon mass…
- Hagelin M-209The US Army's tactical cipher of the Second World War, designed in Stockholm and manufactured by a typewriter company.
- HailoIsraeli fabless company making power-thrifty AI accelerators for devices in the field rather than the data center.
- Hal AbelsonThe MIT professor who co-wrote SICP and was later asked to examine his own university's role in the Aaron Swartz case.
- Hal FinneyThe cypherpunk who helped build PGP, invented reusable proofs of work and received the very first bitcoin transaction.
- Half-band filterA FIR low-pass filter with its cutoff at exactly a quarter of the sample rate, which makes nearly every other coefficient…
- Half-blockUsing the ▀ and ▄ characters to split each text cell into two coloured pixels, doubling the vertical resolution.
- Half-edgeA data structure that captures a mesh's topology by splitting every edge into two directed half-edges, one for each adjacent…
- Half-LambertA shading trick that bends Lambert's diffuse model so surfaces never go fully black on the shadowed side.
- Half-LifeThe game that told its story without ever taking control away from the player — and became the seedbed for the industry's…
- Half-trackingA Commodore 1541 copy-protection trick that hid data between the drive's normal tracks.
- HalftoneReproducing greyscale with dots of varying size — how a printer or press renders a photo using a single colour of ink.
- Hallucination (AI)When an AI confidently makes up facts that aren't true.
- Hallucination mitigationThe collection of techniques for reducing an LLM making up things that sound plausible but are wrong. No method eliminates…
- Halting problemIs there an algorithm that, given any code, can determine whether the code will terminate or run forever? Alan Turing…
- HalvingBitcoin's built-in rule that the reward per block halves every 210,000 blocks — roughly every four years.
- HamlHTML without closing tags: indentation determines nesting, and %div.card is a complete element declaration.
- Hammer (level editor)Valve's level editor for Source and GoldSrc games, which began life as the standalone Quake editor Worldcraft before Valve…
- Hammond organAn electromechanical organ in which spinning tonewheels in front of magnetic pickups make the notes and drawbars mix the…
- Hampster DanceA GeoCities page of dancing hamster GIFs and a sped-up audio loop. One of the very first things to go viral on the web.
- HAMR (heat-assisted magnetic recording)Heat-assisted magnetic recording, which briefly heats a spot with a laser so a hard magnetic grain can be written — pushing…
- Hamza BendelladjAlgerian programmer who, with Aleksandr Panin, ran the SpyEye banking trojan and got fifteen years in a US prison for it.
- Hand scannerThe handheld scanner you dragged down the page by hand — cheap, fiddly, and only as steady as your wrist.
- HandleA unique user ID within a platform, often prefixed with @. Twitter @username, Mastodon @user@instance, Bluesky…
- HandlebarsA template engine built on double curly braces, extending Mustache with helpers and block expressions.
- HandoverMoving an active connection from one cell to the next as the user moves — the entire point of mobile telephony.
- HandspringThe handheld company Palm's founders started after leaving Palm, and the maker of the Treo smartphone.
- Hanno BöckGerman journalist who writes about security holes and, when the supply runs short, finds new ones himself.
- Hans DobbertinGerman cryptographer who broke MD4 and was first to warn about MD5, nearly a decade before everyone else listened.
- Hans Hübner ("Pengo")West Berlin hacker known as "Pengo", the technical engine of the ring that sold break-ins into Western systems to the KGB.
- Hans-Thilo SchmidtGerman cipher office clerk who sold Enigma documentation to French intelligence in 1931.
- Happy EyeballsThe algorithm that makes a dual-stack client try IPv6 and IPv4 in parallel instead of hanging for a minute when the IPv6…
- Haptic feedbackThe interface answering through touch — small, precise vibrations confirming a press on a flat surface with no moving parts.
- Harald NiederreiterAustrian mathematician whose 1986 code-based cryptosystem turned McEliece inside out – and forty years later lives on as…
- Harald WelteGerman developer who first took the GPL to court and then built an open-source mobile network to see what the carriers had…
- Harassment (Trakasserier)Repeated unwanted contact or attacks directed at a person online. Distinguished from one-off rudeness by its persistence…
- Hard restart (SID)A small trick in C64 player routines that resets the SID's envelope generator a few frames before a note, so the attack…
- Hard sync (oscillator sync)One oscillator resets another's phase every time it starts a new cycle, producing a tone that sounds like it is tearing at…
- Hard-sectored diskEarly floppies that marked the start of every sector with a physical hole in the media instead of letting the controller…
- Hardcoded credentialsLogin credentials baked permanently into an application, firmware, or device — often the same across all units and…
- HardwarePhysical components of a computer — CPU, RAM, storage, GPU, motherboard, peripherals. Opposite: software (instructions…
- Hardware keyloggerA small physical device that sits between the keyboard and the computer and logs every keystroke — invisible to the OS and…
- Hardware RAIDDedicated RAID controller card (LSI MegaRAID, Dell PERC, HPE Smart Array) handles RAID operations offloading from CPU. BBU…
- Hardware root of trustA key or code fragment in silicon that the rest of the boot chain has to trust, because it cannot be changed in the field.
- Hardware scrollingScrolling the background by changing a scroll register in the graphics chip instead of redrawing the whole screen in…
- Hardware spriteA video chip's ability to hold a few small movable images with their own coordinates and composite them over the background…
- Hardware tokenPhysical device required to log in — USB/NFC key, smart card, RSA token.
- HardwiredA 1991 Amiga demo by Crionics and The Silents, and one of the most talked-about productions of the Amiga's heyday.
- Harlan CarveyAmerican Windows forensics specialist who taught a generation of investigators that the registry is a diary users don't know…
- Harlem ShakeThe 2013 video format where one person dances alone among people ignoring them, until the bass drops and everyone is…
- HarmanThe audio group behind JBL, AKG and Harman Kardon — and, since 2017, Samsung's route into connected cars, bought for eight…
- Harmonic analyserThe machine that ran the tide predictor backwards: feed it a measured curve and the amplitudes of its component waves fall…
- Harmonic exciterAn effect that generates new harmonics in the top end, giving a dull recording a sheen that was never there in the first…
- HarmonizerAn effects unit that shifts a signal's pitch in real time and lays it alongside the original as a harmony.
- Harmony (Qt clone)The attempt to rewrite Qt from scratch under a free licence so KDE could be built without Trolltech's terms, a project whose…
- Haroon MeerThe South African who turned honeypots into something an ordinary IT team can actually be bothered to deploy.
- Harri HurstiFinnish programmer who in 2005 changed the outcome of an election on a real American voting machine by doing nothing more…
- Harvard architectureInstructions in one memory, data in another — a split Aiken did not choose on principle but because punched tape was all he…
- Harvard Mark IFifty feet of gears, relays and one continuous drive shaft — the machine that named the Harvard architecture and set Harvard…
- Harvard Mark IIAiken's second machine did floating point and could split itself in two — but is remembered for a moth caught in a relay.
- Harvard Mark IIIAiken's third machine, also called ADEC: vacuum tubes in the arithmetic unit, magnetic drums for storage — and instructions…
- Harvest now, decrypt laterRecording encrypted traffic today in order to break it in ten years — the reason migrating to quantum-safe cryptography is…
- HarvesterSUSE's open hyperconverged infrastructure — virtual machines and containers on the same bare metal, built on Kubernetes.
- Hash collisionWhen two different inputs produce the same hash output — provably inevitable (pigeonhole), practically catastrophic for…
- Hash crackingRecovering an input from its hash by guessing candidates and comparing hashes.
- Hash functionDeterministic function mapping arbitrary input to a fixed-length output. Two main categories: fast hashing (for data…
- Hash joinJoin algorithm: build a hash table of the smaller relation (build phase), iterate the larger relation and look up (probe…
- Hash partitionPartitioning strategy: apply a hash function to the partition key, modulo N → pick partition. Even distribution guarantee if…
- Hash table (hash map)Data structure that maps keys to values in O(1) amortised time — the building block behind dict/HashMap/object in nearly…
- HashiCorpThe company behind Terraform, Vault, Consul and Vagrant — the toolkit that made "infrastructure as code" standard practice.
- HashingA one-way function that gives the same input the same output every time — but you can't go backwards.
- HashtagA word prefixed with a hash that makes a post findable by topic — invented by a user, not by the platform.
- Hashtag followFollowing a hashtag (not just an account) so that posts tagged with it appear in your feed. Turns the hashtag from a pure…
- HaskellLazy, pure, statically typed functional programming language. Named after Haskell Curry. First standard 1990, still at the…
- Håstad's broadcast attackAn attack on RSA where the same message is encrypted with a small public exponent for several recipients, and can be…
- Hasura"PostgREST for GraphQL" — point it at Postgres → complete GraphQL API + real-time subscriptions auto-generated.
- HatariAn open-source emulator for Atari's 16- and 32-bit machines — ST, STE, TT and Falcon — and the Atari scene's closest…
- HaujobbDemogroup with German roots in the early 90s, active on both Amiga and PC for more than three decades.
- HAVALA 1992 hash function that could produce 128- to 256-bit fingerprints, with the user choosing how much computation to spend…
- Havoc PenningtonThe Red Hat developer behind Metacity, GConf and D-Bus, and one of the people who started freedesktop.org so GNOME and KDE…
- HavokPhysics middleware that became the de facto standard for rigid-body dynamics in console games — best remembered for the…
- HaxeFlixelThe Flash framework Flixel moved to the Haxe language, so its 2D games could outlive Flash and ship to web, desktop and…
- Hayes command set (AT)The AT-prefixed text commands that have been telling modems to dial, hang up and report on themselves for forty years.
- Hazard pointersA way to know when it is safe to free memory in a lock-free data structure: every thread openly publishes which pointers it…
- HBAHost Bus Adapter — expansion card that connects host to storage devices. Common: SAS HBA (12 Gb/s), Fibre Channel HBA, NVMe…
- HBAOA screen-space ambient occlusion method that measures how much sky each point can see by reading the horizon in the depth…
- HBaseDistributed wide-column NoSQL DB. Inspired by Google Bigtable (2006). Apache project, runs on top of HDFS. Java. Used by…
- HBM (High Bandwidth Memory)Vertically stacked RAM mounted right next to the GPU / AI accelerator — bandwidth in the terabytes-per-second range.
- HBM3eEnhanced HBM3. 1.2 TB/s per stack (vs HBM3's 819 GB/s). 24-36 GB per stack. Standard on Nvidia H200, B100, B200 and AMD…
- HBM4Fourth generation HBM — JEDEC spec 2024, first product deliveries 2026. Double interface width (2048-bit vs HBM3's 1024-bit)…
- HC-128A 2004 stream cipher with a 128-bit key, written for software and driven by large tables in memory rather than shift…
- HCL (HashiCorp Configuration Language)HashiCorp's declarative configuration language — like JSON but for humans. Powers Terraform, Packer, Nomad, Consul, Vault…
- HCTRA wide-block mode with a hash on each side of a counter-mode core, designed for whole disk sectors.
- HDCDA scheme for hiding control data in the audio CD's least significant bit, letting a compatible player recover more than 16…
- HDCP (High-bandwidth Digital Content Protection)DRM system in HDMI/DisplayPort — encrypts video from source to screen, preventing recording.
- HDD (Hard Disk Drive)Mechanical storage with spinning platters and read heads — old tech, still used for cheap mass storage.
- HDFS (Hadoop Distributed File System)Hadoop's distributed filesystem — large blocks, threefold replication, built for throughput rather than latency.
- HDMAThe Super Nintendo's way of writing fresh values into the video registers between every scanline, without the CPU lifting a…
- HDMI (High-Definition Multimedia Interface)The standard digital connector for video + audio — TV, monitor, projector.
- HDMI 2.1The HDMI version that enables 4K @ 120 Hz, 8K @ 60 Hz, VRR, and eARC. Required for full PS5/Xbox Series X output.
- HDMI-CECConsumer Electronics Control — extra signal wire in HDMI cable that lets devices control each other. TV + soundbar + Apple…
- HDR (High Dynamic Range)Images and video with a wider span between darkest and brightest point than traditional SDR, plus more colours. Requires 10…
- HDR10Open standard for HDR video — 10-bit colour, Rec.2020 colour space, PQ (Perceptual Quantizer) transfer function, static…
- Head crashWhen the read/write head touches the spinning platter and scrapes away magnetic coating and data in a fraction of a…
- Head gapThe tiny non-magnetic slit in the ring-shaped head where the field leaks out to magnetise the medium.
- Head parkingMoving the read/write heads to a safe place before the disk stops, so they don't land on and scratch the data-bearing…
- Head skewAn offset in the sector numbering between tracks under different heads in the same cylinder, so a head switch doesn't miss…
- Header-PeopleThe ARPANET list where the email header format was argued into existence — usually in very long messages.
- HeadlampOpen source Kubernetes UI. CNCF Sandbox 2022. Web + desktop (Electron). Modern alternative to stale Kubernetes Dashboard…
- Headless browserA browser without a graphical window — controlled programmatically for testing, scraping, screenshot generation, PDF…
- Headless CMSContent management system without a built-in presentation layer. Delivers content via REST or GraphQL → frontend fetches +…
- Headless UIUnstyled but fully accessible components for React and Vue, built by Tailwind Labs (2020). You get the behaviour — focus…
- Headphone amplifierThe amplifier stage that drives headphones, where output impedance matters more than the power figures on the box.
- HeadroomThe gap between the level you normally work at and the level where the signal clips.
- Health-check endpointA special URL (often /healthz or /readyz) that a service exposes solely to report its own health. Load balancers, Kubernetes…
- HeapThe area for dynamic memory — where "new" or "malloc" allocates.
- Heap tableA table without a clustered index — rows are stored unordered wherever there's room, not sorted on any key. PostgreSQL…
- HeapsA Haxe game engine from the man who wrote Haxe, best known as the machinery under Dead Cells.
- HeartbleedCVE-2014-0160 in OpenSSL TLS heartbeat extension. Memory disclosure bug: ask server for 64KB "heartbeat data" + false length…
- Heat pipeSealed copper tube with a working fluid (water typical) + wicking structure. Phase-change cooling: hot-end vaporizes fluid…
- Heat spreader (IHS)The metal lid on top of a processor that the cooler actually touches. Spreads heat from a small hot area to a larger one…
- Heath RobinsonBletchley Park's first machine aimed at the Lorenz cipher, named after a cartoonist famous for ludicrously overcomplicated…
- HeatsinkA chunk of aluminium or copper that pulls heat away from a hot component into the surrounding air.
- heaven7A 64k intro by Exceed (2000) that ray-traced reflective spheres in real time — long before graphics cards did.
- Hebbian learning"Cells that fire together wire together" — the rule that explained how neurons learn.
- Hebern machineOne of the first rotor machines, and a reminder that Enigma was not the only one to have the idea.
- Hector MartinSpanish console hacker in fail0verflow who showed that Sony signed PS3 code with a constant nonce, and who later founded…
- Hector MonsegurLulzSec leader "Sabu", arrested in 2011, who then spent months running the group on behalf of the FBI.
- Heightfield colliderA collision shape for terrain that stores only one height per grid point and leaves the triangles implied.
- HeightmapA grayscale image whose pixel values encode terrain elevation, turning a 2D texture into a 3D landscape.
- HeimdallFree software that reverse-engineered Samsung's Odin protocol so Galaxy devices can be flashed from Linux and macOS, not…
- Helen NissenbaumPhilosopher who replaced "is it public or private?" with the far more useful "does this information flow match the norms of…
- Helical scanSpinning heads on a tilted drum write diagonal tracks — high relative speed without racing the tape back and forth.
- HeliconeLLM observability via proxy — change your OPENAI_BASE_URL to Helicone and everything is logged automatically. Or use the…
- Helium driveA hard drive hermetically sealed and filled with helium instead of air, to squeeze in more and thinner platters.
- HelixA modal editor written in Rust, first released in 2021. It inverts Vim's grammar: you select first and act second, a model…
- HellthreadMastodon/Fediverse phenomenon: a thread that grows uncontrollably as more people are @-mentioned and everyone gets a…
- HelmPackage manager for Kubernetes — a "Helm chart" is a template for installing an application.
- Helm chartPackaged template for a Kubernetes application — YAML with variables you fill in.
- HelmfileDeclarative wrapper for Helm — define all releases in one YAML file, apply atomically. Roboll, 2017. Pitch: what…
- Helmut SchreyerWanted to build Zuse's machine out of vacuum tubes instead of relays, was turned down by the German authorities, and watched…
- Henry SpencerThe Toronto programmer behind C News, one of the most widely copied regex libraries, and the oldest surviving Usenet archive.
- Henryk ZygalskiOne of the three Polish mathematicians who broke Enigma; inventor of the perforated sheets that bear his name.
- HEPnetThe particle physicists' own computer network in the 1980s, built on DECnet and linking laboratories on both sides of the…
- Herbert BosProfessor at Vrije Universiteit Amsterdam whose group, VUSec, has made a habit of proving that hardware faults are software…
- Herbert SimonThe only person holding both the Turing Award and the Nobel Prize in Economics — for fundamentally the same idea, that…
- Herbert YardleyFounder of America's first peacetime codebreaking bureau, who responded to its closure by writing a bestseller about…
- herbstluftwmA manual tiling window manager that divides the screen into frames the user splits by hand, with all configuration applied…
- Hercules Computer TechnologyThe company behind the Hercules Graphics Card, which taught the IBM PC's crisp monochrome monitor to draw graphics.
- Herding attackAn attack in which you publish a hash value first and later manufacture a message with any prefix you like that matches it.
- Herman GoldstineThe Army's mathematician at the Moore School, and the man who happened to meet von Neumann on a railway platform.
- Herman HollerithThe engineer who turned statistics into machine work — and who invented a business model good enough to outlive him by a…
- HerokuThe original "git push heroku" PaaS — defined the Twelve-Factor App. Salesforce bought in 2010, free tier killed in 2022.
- Hershey fontsTypefaces defined as straight lines between coordinates, drawn for machines that hold a pen rather than lay down dots.
- HesiodProject Athena's trick for getting DNS to answer questions that had nothing to do with hostnames — users, groups and where…
- Heterogeneous coresA CPU design where different core types with different strengths exist on the same chip — typically a few large performance…
- HetznerGerman hosting company known for dramatically cheaper pricing than AWS/Azure — €4/mo for a cloud VPS, €40/mo for a dedicated…
- Hewlett Packard Enterprise (HPE)The half of the old Hewlett-Packard that got the servers, storage and networking — and then went shopping for supercomputers…
- Hewlett-PackardThe Palo Alto garage company often called Silicon Valley's starting point, which ended up as two separate businesses.
- Hex (Hexadecimal)Number system with base 16 — digits 0–9 + letters A–F. Each hex character represents 4 bits (nibble), two hex characters =…
- Hexagonal Architecture (Ports & Adapters)Domain logic in the centre, surrounded by rings of "ports" (interfaces) and "adapters" that translate to database, HTTP…
- Hexagonal gridA game map divided into hexagons instead of squares, so all six neighbours sit at exactly the same distance from the centre.
- HexChatA graphical IRC client for Linux and Windows, started in 2011 as a fork of X-Chat when the original stopped getting updates…
- HFP (Hands-Free Profile)The Bluetooth profile for two-way phone calls, designed for car kits and the reason headphones start sounding like a tin can…
- Hi-MDSony's final MiniDisc upgrade, from 2004 — 1 GB per disc, drag-and-drop files over USB and uncompressed audio.
- Hi-res audioDigital audio with a higher sample rate or bit depth than CD's 44.1 kHz and 16 bits — and a never-ending argument about…
- HibernateJava's dominant ORM — Gavin King, 2001. Standardized into JPA (Java Persistence API). Default in Spring Boot, JEE.
- Hidden partA concealed section of a demo that only appears if you press the right key combination or do something unexpected.
- hidden="until-found"HTML value that hides content but still lets the browser's find-in-page locate it — and reveals it automatically when the…
- Hierarchical pathfindingSplitting the map into coarse regions and searching a rough route between them first, then refining it within each region.
- Hierarchical state machineA state machine whose states can contain their own substates, so shared behaviour is written once in the parent.
- Hierarchical task network (HTN)A game-AI planning method that breaks high-level goals into subtasks until only directly executable actions remain.
- Hierarchical Z (Hi-Z)A downscaled pyramid of the depth buffer where each tile remembers its coarsest depth, so whole surfaces can be rejected…
- HiFDSony and Fujifilm's 200 MB floppy meant to succeed the diskette — killed by a head crash and the USB stick.
- High availability (HA)System architecture designed to survive single component failures without downtime.
- High density (HD)The floppy class that doubled capacity to 1.44 MB with a harder magnetic coating and twice the sectors per track.
- High-NA EUVThe next generation of EUV lithography with a higher numerical aperture (NA 0.55 vs today's 0.33), which draws even finer…
- High-pass filterA filter that lets the treble through and attenuates everything below a cutoff frequency — the low-pass filter's mirror…
- HighchartsCommercial JavaScript charting library. Torstein Hønsi (Norway), 2009. Free for personal/non-commercial use, paid for…
- Higher-order differential attackA differential attack that looks at higher-order differences of ciphertext across a set of plaintexts.
- Higher-order functionA function that takes function(s) as arguments or returns a function. map, filter, reduce are classics. Requires first-class…
- HikvisionThe world's largest maker of surveillance cameras, partly state-owned and therefore as much a geopolitical issue as a…
- Hilarie OrmanThe cryptographer behind Oakley, the key exchange protocol that became one half of IKE and so sits inside every IPsec tunnel.
- Hill cipherEncrypts blocks of letters by matrix multiplication modulo 26. Elegant algebra, and for exactly that reason transparent to…
- Hill climbing (cryptanalysis)A search method that swaps two letters in a guessed key and keeps the swap if the resulting plaintext looks more like…
- Hinge jointA physics constraint that allows rotation about a single axis only, like a door hinge, a knee or a wheel axle.
- Hinted handoffWhen a replica is down, the write is stored at a neighbour node as a "hint" — on reconnection the hints are replayed so the…
- HipCrimeThe pseudonym behind one of the most sweeping attacks on Usenet in the late 1990s, with floods of posts and forged cancel…
- Hires (C64)The Commodore 64's high-resolution bitmap mode: 320×200 pixels, but only two colours per 8×8 cell.
- Hiroaki EtohJapanese IBM researcher behind ProPolice, the compiler defence that became GCC's -fstack-protector.
- Hirose constructionA double-block-length compression function in which two encryptions share one key and are told apart by a constant.
- HisenseA Chinese electronics group from Qingdao that grew from a radio factory into one of the world's largest TV makers — partly…
- Hit stopThe game freezes animation and motion for a few frames at the moment of impact so a hit feels like it connects.
- HitachiJapanese industrial giant that built everything from electric motors to IBM-compatible mainframes, and for a while owned the…
- HitboxAn invisible shape attached to a game object that decides what counts as a hit — rarely the same thing as the image you see.
- HitscanA weapon whose shot lands instantly along a straight line the same frame the trigger is pulled, with no projectile…
- HitstunThe brief window in which a struck character can do nothing at all — the grammar fighting games use for what is allowed to…
- Hive MetastoreCentral catalog for data lake tables: which tables exist, their schema, partition structure, file format, S3 paths. Launched…
- HivelyTrackerAn open-source tracker from 2006 that builds on the Amiga's AHX format to make tiny, synthetic-sounding chiptunes on modern…
- HKDFHMAC-based Key Derivation Function (RFC 5869) — takes input keying material and produces an arbitrary number of…
- HKDF-Expand-LabelThe thin wrapper around HKDF-Expand that TLS 1.3 uses to derive every individual key, IV and secret.
- HKT (Higher-Kinded Types)Type-system feature: abstract over type constructors (types that take types as parameters). Enables generic-over-generics…
- HLODHierarchical LOD — distant objects are merged into a single simplified proxy mesh to slash draw-call counts at long range.
- HMAC (Hash-based Message Authentication Code)A way to sign messages with a shared secret — the recipient can verify the message wasn't tampered with and comes from the…
- HNSW (Hierarchical Navigable Small World)Hierarchical Navigable Small World — the dominant graph-based algorithm for approximate nearest-neighbor search among…
- HOCON"Human-Optimized Config Object Notation". Typesafe (later Lightbend), 2011. JSON superset with comments, includes, variable…
- Hofstadter's law"It always takes longer than you expect, even when you take into account Hofstadter's law."
- HoistingJS phenomenon: variable and function declarations are "hoisted" to the top of their scope at compile time.
- Hold-and-Modify (HAM)The Amiga's cheat mode that showed all 4096 colours at once by letting each pixel tweak just one colour component of its…
- Hollerith codeThe character encoding on a punched card: twelve positions per column, where one hole is a digit and two holes are a letter…
- Hollerith machineThe tabulator that counted the 1890 US census — and that became IBM by way of a company name.
- Homebrew (brew)The "de facto" package manager for macOS — brew install postgresql. Own formulas (Ruby) per package, installed in an…
- Homestar RunnerFlash cartoon comedy site run by two brothers from Georgia, entirely without advertising, which in the early 2000s was one…
- HometownA Mastodon fork (Darius Kazemi) whose signature feature is "local-only posting" — the ability to write posts that stay on…
- Homogeneous CoordinatesA four-component representation of 3D points that unifies rotation, translation, and perspective projection into single…
- Homophonic substitution cipherA substitution cipher that gives common letters several cipher symbols to choose from, so frequency analysis finds no peaks…
- HoneycombObservability platform focused on distributed tracing and high-cardinality events — Charity Majors and Christine Yen, 2016…
- HoneypotA fake server or resource set up to attract and track attackers.
- HoneywellThe thermostat maker that spent thirty years as one of IBM's competitors, and whose minicomputers routed the first packets…
- HonoUltrafast web framework. Yusuke Wada, 2022. Runs on Cloudflare Workers, Bun, Deno, Node.js, AWS Lambda. Modern Express.js…
- Hopper (H100)Nvidia's datacenter GPU generation from 2022. H100 (80 GB HBM3) drove the entire AI boom 2023-2024. TSMC 4N process. 814 mm²…
- Horizontal blank (HBlank)The short pause as the beam jumps from the end of one line to the start of the next — the window for per-line tricks.
- Horizontal Pod Autoscaler (HPA)A Kubernetes mechanism that automatically adjusts the NUMBER of pod replicas based on load — e.g. CPU, memory, or custom…
- Horizontal ScrollingGraphics technique where content slides left or right, revealing a larger world than the screen can display at once.
- Hornet ArchiveThe PC demoscene's main file archive in the 1990s, at hornet.org — where you fetched demos, music and diskmags before…
- Horst FeistelThe German-American at IBM who gave the block cipher its structure — and thereby DES, and thereby twenty years of banking…
- Horton principleAuthenticate what is meant, not just what is said — a MAC should cover the whole interpretation of a message, not merely its…
- HortonworksThe Hadoop company Yahoo spun out with its own engineers, which ended up merging with its fiercest rival eight years later.
- Host migrationThe mechanism that lets another player take over as server when the host of a player-hosted match disconnects.
- HostGatorThe shared-hosting era personified — started in a dorm room, sold for a quarter of a billion dollars.
- HostingerLithuanian web host that built an empire on being the cheapest name in the room.
- HostmaskIRC's way of identifying a user: nickname, username and host in the form nick!user@host, wildcards welcome.
- HOSTS.TXTThe whole of ARPANET's name resolution in a single text file, which every machine periodically downloaded from the same…
- HOT (Heap-Only Tuple)The PostgreSQL optimisation that lets an update avoid writing new entries into every index. The difference between a table…
- Hot cornerA screen corner that triggers something when the pointer is driven into it — an overview, a screensaver, a window switcher…
- Hot partitionUneven load distribution where one (or a few) partitions get disproportionate traffic. Classic sources: timestamp-based…
- Hot reload (HMR)When you save a code file and the app updates instantly in the browser — without losing state.
- Hot standbyA replica database that is ready to take over (failover) and available for reads at the same time.
- hot_standby_feedbackThe setting that lets a read replica tell the primary what it still needs, so long queries don't get cancelled mid-flight…
- Hotels.comExpedia-owned hotel booking site — known for "Captain Obvious" as mascot, "stay 10 nights, get 1 free" rewards (changed…
- HotlinkDirect-link to a resource (often an image) on someone else's server from your own page. <img…
- Hotwire"HTML Over The Wire" — the Rails stack that powers Hey and Basecamp without an SPA framework.
- HousemarqueA Finnish studio that stubbornly made particle-heavy arcade games for a quarter of a century before landing a big hit.
- Hovav ShachamThe researcher who showed you don't need to inject any code to hijack a program — the code already there will do.
- Howard AikenThe physicist who got IBM to build his calculating machine and then forgot to mention them at the unveiling.
- Howard RheingoldThe writer who gave "virtual community" its meaning, in a book built on his years on The WELL.
- Howard SchmidtAmerican security veteran who advised two presidents and was dubbed "cyber czar" by the press, though the job carried far…
- HP 3PARThe storage array whose thin provisioning set off a 2010 bidding war between HP and Dell.
- HP DeskJetHP's 1988 inkjet that brought thermal inkjet printing to the home and small office.
- HP IncThe half of Hewlett-Packard that got to keep the name, the PCs and — above all — the ink cartridges.
- HP LabsHewlett-Packard's central research lab in Palo Alto — birthplace of PA-RISC, the idea behind Itanium, and the most…
- HP LaserJetHP's 1984 laser printer that moved the technology from the machine room onto the desktop.
- HP NewWaveHewlett-Packard's object-oriented desktop layered over Windows 2 in 1988, remembered mostly because Apple sued it.
- HP OpenViewHP's network monitor that, for decades, drew the map of the enterprise network over SNMP.
- HP ThinkJetThe first mass-market thermal inkjet printer — the name is the technology, abbreviated.
- HP VUEHewlett-Packard's Motif-based desktop for HP-UX, which became the blueprint for CDE.
- HP-35Hewlett-Packard's first scientific pocket calculator, 1972, which made the slide rule obsolete almost overnight.
- HP-GLHewlett-Packard's vector language for plotters, where the image is described as pen movements rather than dots.
- HP-UXHewlett-Packard's Unix from 1984 — a System V descendant still keeping Itanium mainframes alive.
- HPAHorizontal Pod Autoscaler — Kubernetes controller that scales the number of pod replicas based on metrics. Standard target…
- HPE GreenLakeHPE's answer to the cloud — pay-per-use for hardware that sits in your own datacenter instead of Amazon's.
- hpwmHewlett-Packard's late-1980s window manager for X, whose bevelled frames OSF picked as the public face of Motif — mwm is…
- hqxA family of pixel-art scaling filters that compare each pixel with its eight neighbours and blend in smooth edges.
- hreflangHTML attribute that tells Google: "this page is also available in these languages".
- HRTFHead-Related Transfer Function — the filter that your head, torso and outer ear impose on a sound, and that the brain reads…
- HSMA box whose entire business model is that the key never leaves it, not even for you.
- HSM API attackExtracting keys from a security module purely by chaining calls that are each perfectly legitimate on their own.
- HSRPHot Standby Router Protocol — Cisco's proprietary gateway failover protocol. Two routers share virtual IP + MAC. Predecessor…
- HSTS (HTTP Strict Transport Security)HTTP header that tells the browser "this site must never be reached unencrypted".
- HSTS preloadList of domains that all major browsers (Chrome, Firefox, Safari, Edge) hardcode as "always HTTPS — never allow HTTP"…
- HTAPHybrid Transactional/Analytical Processing — a database architecture that runs both transactions (OLTP) and analytics (OLAP)…
- HTB (Hierarchical Token Bucket)Linux tc qdisc for hierarchical bandwidth allocation. Define root + children classes with rate + ceil. Classic use: share…
- HTCThe Taiwanese phone maker that built the first Android handset, briefly led the US market, and then sold its engineers to…
- HTML (HyperText Markup Language)The structure of a web page — what's a heading, a paragraph, a link or an image.
- HTML Templates (<template>)Native HTML element to declare inert DOM snippets — parsed but not rendered until cloned via…
- HTML5Fifth major version of HTML. W3C recommendation 2014. Added semantic elements, canvas, video/audio, web storage, web…
- HTMXLibrary that lets you build dynamic UI with just HTML attributes — no React, no JS state.
- htmx 2.0Big 2.0 release (June 2024) — dropped IE support, made WebSocket + SSE into "extensions". Carson Gross continues to drive…
- htmx triggershtmx attribute hx-trigger controls when AJAX request should be sent. Default: form-submit, button-click, link-navigation…
- htopAn interactive process viewer for the terminal, written by Hisham Muhammad in 2004 as a usable alternative to top. Colours…
- HTTP (HyperText Transfer Protocol)The protocol web browsers and web servers use to talk to each other.
- HTTP Request SmugglingAttacker exploits disagreement between front-end proxy and back-end server about HTTP message boundaries. CL.TE, TE.CL…
- HTTP/2Second major version of HTTP. RFC 7540 (2015). Based on Google's SPDY experiment. Binary (not text), multiplexed over a…
- HTTP/3HTTP-over-QUIC — RFC 9114 (2022). QUIC is encrypted transport over UDP port 443. Eliminates TCP head-of-line blocking…
- HTTPS (HTTP Secure)HTTP, but encrypted with TLS so nobody can eavesdrop or tamper with the traffic.
- HuaweiThe Shenzhen telecom vendor that became the world's largest, and then a foreign-policy file.
- HubbleThe observability layer on top of Cilium, showing which traffic actually flows in the cluster — and which rule stopped the…
- HubSpotThe marketing company out of MIT that coined "inbound marketing" and made a free CRM the door into everything that costs…
- HubzillaA federated platform (Mike Macgirvin) known for "nomadic identity" — your identity isn't locked to a single server. Via the…
- Huddle (Slack)A lightweight, spontaneous audio call in Slack started with one click in a channel or DM — meant to recreate the low barrier…
- Hudson message baseThe QuickBBS-era message format, in which every conference on the board was crammed into the same five files.
- Huge pageMemory page larger than the standard 4 KB: 2 MB or 1 GB. Reduces TLB pressure dramatically for applications with large…
- Huge page (TLB)The use of large memory pages (2 MB or 1 GB instead of the standard 4 kB) to reduce pressure on the TLB. Since each TLB…
- Huge pagesMemory pages that are much larger than the standard 4 KB size — typically 2 MB or 1 GB. Fewer, larger pages reduce pressure…
- Hugging Face"GitHub for AI" — model hub with 1M+ open-weight models, the transformers library, datasets, Spaces (host AI demos). The…
- Hugh ThompsonA software tester who ended up as the public face of the world's biggest security conference.
- HugiLong-running disk magazine for the PC demoscene, driven by its editor Adok.
- HugoA static site generator written in Go, started in 2013 by Steve Francia. It markets itself on speed and delivers: thousands…
- Hugo KrawczykThe cryptographer behind HMAC and HKDF — two constructions that run every time a browser speaks TLS.
- HUI (Human User Interface)Mackie and Digidesign's 1997 control surface for Pro Tools, whose MIDI protocol outlived the hardware by more than two…
- Human computerFor three hundred years a computer was a person with paper, a pencil and one operation to perform over and over.
- Human-NetsA late-1970s ARPANET list about how computer networks affect people, conducted over a computer network by people who were…
- humanities.*The eighth and last official Usenet hierarchy, added in 1995 for literature, art, philosophy and the rest of the humanities.
- HumanizeA sequencer function that adds small random deviations in timing and velocity, so programmed parts sound less like a machine.
- Humble BundleIt began as "pay what you want" bundles with a slice to charity and became a store and a subscription.
- Hummingbird ExceedThe commercial X server for Windows that, through the 1990s, turned the office PC into an X terminal for the company's Unix…
- Hunk formatThe Amiga's format for programs and object files — a chain of "hunks" the loader relocated in memory at launch.
- HuntressSecurity for small businesses that can't afford a SOC, sold through the IT provider they already have.
- Hurricane ElectricFremont-based ISP that built one of the best-connected backbones on the internet by peering with almost anyone who asks.
- HurtboxThe hitbox's counterpart: the zone on a character that receives damage, as opposed to the one that deals it.
- Hut 6Bletchley Park's hut for Enigma traffic from the German army and air force.
- Hut 8The section at Bletchley Park that worked on the German naval Enigma, initially led by Alan Turing.
- HVSC (High Voltage SID Collection)The near-complete archive of Commodore 64 music — tens of thousands of SID tunes collected since 1996.
- Hybrid appAn app that is really a web page in a native shell — one codebase for every platform, at the cost of feeling like a web page.
- Hybrid bondingJoining two pieces of silicon by pressing their surfaces together so the copper contacts fuse directly, with no solder balls…
- Hybrid encryptionEncrypt the data with a fast symmetric key, then encrypt that key with an asymmetric system, so no single algorithm has to…
- Hybrid Logical Clock (HLC)A clock that combines physical time (wall clock) with a logical counter, so you get timestamps that are both close to real…
- Hybrid searchSearch strategy that combines dense (vector) and sparse (BM25/lexical) — captures both semantic similarity and exact term…
- Hybrid search (RAG)Combining vector search (semantic similarity) with classic keyword search (BM25/lexical) in a RAG pipeline, and merging the…
- HyDEHypothetical Document Embeddings — a retrieval technique where you first have an LLM generate a made-up "ideal answer" to…
- Hydra (file transfer)A bidirectional file transfer protocol for FidoNet mailers that sent and received at the same time over a single modem line.
- HydrationThe process where client-side JS "wakes up" server-rendered HTML — attaching event listeners and recreating reactive state…
- Hydraulic erosionA terrain technique that simulates water flowing, tearing loose sediment, carrying it along and depositing it lower down…
- Hydrogen (drum machine)A pattern-based open-source software drum machine, long the default beat in the Linux studio.
- Hyper-GAn Austrian hypertext system from the early 1990s that solved broken links before the web had really got round to having any.
- Hyper-VMicrosoft's hypervisor, shipped in 2008 with Windows Server 2008. Type 1, despite appearing to run inside Windows — enable…
- HyperlinkClickable reference from one document to another. The basis of the web. Implementation: HTML <a href="...">. Vannevar Bush…
- HyperLogLogProbabilistic data structure that counts distinct elements in a stream using constant memory — Flajolet et al. (2007). 12 KB…
- HyperLookA HyperCard-style environment for NeWS, where both the interface and its logic were PostScript running inside the window…
- HyperscriptDSL for client-side scripting, built by htmx creator Carson Gross. English-readable syntax: on click toggle .open on me…
- HyperTerminalThe terminal program bundled with Windows from 95 to XP — for many people the first and only way onto a BBS.
- Hyperthreading (SMT)Intel's name for Simultaneous Multithreading (SMT). One physical CPU core exposes two logical cores by sharing execution…
- HypervisorSoftware that runs virtual machines — lets one physical computer host multiple OSes at once.
- HyperXA gaming-peripherals brand — originally Kingston's memory line, owned by HP since 2021.
- HyprlandThe Wayland compositor that made animations, rounded corners and blur the main event rather than an afterthought — started…
- Hysteresis loopThe curve showing how a ferromagnet's magnetisation lags the applied field — and why a written bit stays put.
- HYTELNETA hypertext directory of everything reachable by telnet, written before there was a web to put it on.
- NVIDIA H100The datacenter GPU that became the AI boom's bottleneck and NVIDIA's ticket to a trillion dollars.
- TCP handshakeThe three-step process that opens a TCP connection: SYN → SYN-ACK → ACK.
- Turbo (Hotwire)Hotwire's main component — replacement for full-page navigation. Turbo Drive (fast page loads), Turbo Frames (partial…
I
- #includeC/C++ preprocessor directive for including another code file. #include <stdio.h> (system) or #include "myheader.h" (local)…
- i18n (Internationalization)Building software so that it can be adapted to other languages and regions — the abbreviation is i, 18 letters, n.
- I²C busInter-Integrated Circuit — a serial bus (Philips, 1982) connecting several chips with just two wires: data (SDA) and clock…
- I²SInter-IC Sound — Philips' 1986 serial bus for moving digital audio between chips on the same board.
- i3The tiling window manager most X11 users tried first, with a readable config file and windows arranged in a tree.
- i3lockThe screen locker from the i3 project: a solid colour or an image across the screen, a password checked through PAM, and as…
- IaaS (Infrastructure as a Service)Cloud services at the lowest level of abstraction — virtual machines, storage, networking. You manage OS + above yourself…
- IaC (Infrastructure as Code)Define servers, databases, firewalls in code instead of clicking around the cloud console.
- IAM (Identity and Access Management)Managing who's allowed to do what in a system — users, roles, policies, tokens.
- IAM roleAWS concept: an identity you assume temporarily — not permanent credentials.
- Ian BeerThe Project Zero researcher who showed an iPhone could be taken over by radio while sitting untouched in its owner's pocket.
- Ian GoldbergCanadian cryptographer who broke Netscape's SSL as a student and later invented OTR, the protocol that taught chat to forget.
- Ian GriggFinancial cryptographer who in 1996 came up with the Ricardian contract: an agreement that both people and programs can read.
- Ian MiersAmerican researcher who, as a PhD student, wrote Zerocoin and Zerocash — the papers that became the Zcash cryptocurrency.
- Ian Murphy (Captain Zap)American hacker who reset the clocks on AT&T's billing computers in 1981 and became the first person convicted of a computer…
- IAPMIntegrity-Aware Parallelizable Mode – one of the first modes of operation to deliver both confidentiality and integrity in a…
- IAR SystemsThe Uppsala company whose C compilers sit behind the firmware in a remarkable share of the world's gadgets.
- IAS machineThe computer nobody patented, and which was therefore rebuilt in a dozen variants across half the world.
- IBANAn international account number format with a country code and two check digits, so that typos are caught before the money…
- iBGP vs eBGPThe two ways to run BGP: eBGP between different autonomous systems (e.g. your network toward your ISP), and iBGP between…
- IBMThe industry's oldest giant — punch cards, mainframes, the personal computer, and a capacity to survive every technology…
- IBM 029The beige item of furniture an entire generation of programmers wrote their code on, one card and eighty columns at a time.
- IBM 1403The 1959 chain printer that set the industry's benchmark for print quality and stayed in machine rooms for twenty years.
- IBM 3480IBM's 1984 half-inch cartridge that retired the open 9-track reel in the mainframe room and made tape robots practical.
- IBM 3800The first laser printer actually delivered to paying customers, a year ahead of Xerox — and roughly the size of two…
- IBM 405The tabulator that could print letters and not just digits — the machine IBM lived off for fifteen years.
- IBM 4758IBM's late-1990s PCI crypto card, the first product certified at the top level of FIPS 140-1.
- IBM 601The punched-card machine that could multiply — a small-sounding step that separated bookkeeping from computation.
- IBM 604IBM's first mass-produced electronic product: a calculating punched-card machine with fourteen hundred tubes, programmed by…
- IBM PCIBM built a computer out of other people's parts in a year — and thereby lost control of the industry it created.
- IBM ProprinterIBM's dot matrix printer for the PC, best remembered for going together without a single screw.
- IBM SelectricIBM's 1961 typewriter in which a rotating type ball replaced the traditional type bars.
- IBM SSECIBM's answer to losing the credit for the Harvard Mark I — 12,500 vacuum tubes and 21,400 relays, installed behind plate…
- IBM WheelwriterIBM's electronic daisy-wheel typewriter from 1984, the successor to the golf-ball Selectric.
- ICB (Internet Citizen's Band)A late-1980s chat system that competed with IRC for the same idea, lost, and somehow never quite shut down.
- ICCCMThe rulebook for how X applications and window managers talk to each other — famously both indispensable and nearly…
- ICE (Interactive Connectivity Establishment)The protocol that finds a path between two peers behind separate NATs by testing every plausible route at once.
- iCE (ANSI group)The ANSI art group that was ACiD's main rival during the BBS era's heyday, with monthly artpacks of its own.
- ICE (Inter-Client Exchange)X11R6's general-purpose transport for X programs that need to talk to each other without going through the X server — best…
- iCE colorsAn ANSI-art technique that turns off text blinking to free all 16 colours for use as backgrounds too.
- Ice CubesA modern, open source Mastodon client for iOS built in SwiftUI (Thomas Ricouard). Free and rapidly developed, often used as…
- iceauthXauth's twin for ICE connections: edits the file of cookies that session managers and their clients show each other — best…
- iCEDrawDOS ANSI editor from the art group iCE, built for artists who had outgrown TheDraw.
- IceshrimpA Fediverse server software that began as a fork of Misskey/Firefish but was then rewritten to be more maintainable and…
- IceWMA lightweight window manager with a taskbar and start menu, for anyone who wanted Windows 95 ergonomics on a Linux box with…
- ICL (International Computers Limited)Britain's national computer champion, welded together by the government in 1968 to hold off IBM and eventually bought by…
- ICMP (Internet Control Message Protocol)The protocol behind ping and network error messages.
- ICMP floodDDoS via massive ICMP Echo Request packets (ping). Classic but outdated — modern infrastructure rate-limits ICMP…
- ICMP RedirectICMP type 5 — router tells the host "don't send to me, send directly to this router instead". Optimisation mechanism from…
- Icon box (mwm)mwm's optional window that gathers the icons of all iconified windows into one scrollable box instead of scattering them…
- Icon manager (twm)twm's list of every window on screen, where one click iconifies a program or brings it back — a taskbar eight years before…
- Icon themeFreedesktop's directory layout and lookup rules that let a program ask for the icon document-open and get it in the right…
- IconifyX11's word for minimising: the window leaves the screen and is replaced by an icon, or a line in a list, until someone wants…
- ICQThe first mass-popular instant messenger — released in 1996 by the Israeli company Mirabilis, name from "I Seek You", famous…
- id SoftwareHalf a dozen programmers in Texas who invented both the first-person shooter and the business model for spreading it.
- id TechThe umbrella name for id Software's engine lineage — nearly all of it architected by John Carmack, and nearly all of it…
- IDE (Integrated Development Environment)Text editor + compiler + debugger + autocomplete + 100 other things — all in one program.
- IDE vs EditorIDE = "heavy", batteries included (debugger, refactor, test runner). Editor = "lightweight", customisable via plugins.
- IDEAInternational Data Encryption Algorithm — the block cipher PGP picked when DES looked too flimsy.
- Ideal cipher modelA proof model in which the block cipher is treated as an independent random permutation for every key, queryable in both…
- IdempotencyOperation that produces the same result whether run once or many times. Crucial in distributed systems where retries are…
- IdempotentAn operation that produces the same result no matter how many times you run it.
- Idempotent writeOperation that has the same effect regardless of how many times it runs. UPDATE users SET email='x' WHERE id=1 is idempotent…
- Ident (protocol)A protocol that lets a server ask the client machine which user owns a given TCP connection.
- IdentifierA name for something in the program — variable, function, class, module. The rules for valid names vary per language.
- IDFAApple's advertising identifier — a unique string per device that let advertisers follow a user between apps.
- IDORInsecure Direct Object Reference — access-control failure where app exposes object IDs (in URL or body) without verifying…
- iDRACDell's embedded remote-management controller in PowerEdge servers — HP's iLO, but from Dell.
- IDS / IPS (Intrusion Detection/Prevention System)Monitoring system that detects attacks (IDS) or actively blocks them (IPS).
- IEEE 1284The 1994 standard that formalised the PC parallel port and made it bidirectional.
- IEEE 754The floating-point standard — the reason 0.1 + 0.2 does not equal 0.3 in practically every programming language.
- ifcicoThe Unix FidoNet mailer that let a Linux box dial up and swap mail with the DOS world's bulletin boards.
- IFF (Interchange File Format)Electronic Arts' chunk-based container format from 1985 — the ancestor of how modern file formats package their data.
- IFF ANIMThe Amiga's animation format: an opening ILBM frame followed by delta frames that describe only what changed since the last…
- IFLITwo FLI pictures shown on alternate frames and offset by one pixel, so the eye blends colours and resolution the C64 doesn't…
- IFNAThe International FidoNet Association — an attempt to give FidoNet a formal organisation, and proof that the sysops didn't…
- iframeHTML element that embeds an entirely different page inside the current one.
- IFTTT (If This Then That)Consumer-focused precursor to Zapier — coined the "if this then that" phrase. Strong in smart home and social media…
- IGE modeA block cipher mode that chains each block to both the previous plaintext and the previous ciphertext, and where errors…
- IGMPInternet Group Management Protocol — IPv4 multicast membership protocol. Hosts subscribe to multicast groups via IGMP…
- Igor SkochinskyHex-Rays developer, working on the IDA disassembler, who was the first to publicly map out how Intel's Management Engine…
- ihave/sendmeUsenet's ask-before-sending scheme: a neighbour received a list of article IDs and ordered only the articles it was missing.
- ihnp4The AT&T machine in Illinois that was the busiest hub of the 1980s UUCP network, and therefore the first hop in thousands of…
- IIR filterA digital filter that feeds its own output back in — cheap to compute, a close cousin of analogue circuits, and perfectly…
- IKE / IKEv2Internet Key Exchange — protocol for IPsec key-management. Establishes Security Associations (SAs) between peers. IKEv2 (RFC…
- Ikutaro KakehashiJapanese engineer and executive (1930–2017) who founded Roland and was one of the people who made MIDI happen.
- ILBMThe Amiga's standard image format: an IFF-based raster format that stores bitplanes interleaved line by line.
- Ilfak GuilfanovThe man behind IDA, the disassembler that for thirty years was the first thing an analyst opened.
- Illegal opcodesUndocumented instructions in the MOS 6502/6510 that scene coders exploited for tighter, faster code than the maker ever…
- IllumioThe security company that assumes the attacker is already inside and simply wants to stop them getting any further.
- iLOHP's embedded remote-management controller in ProLiant servers — its own CPU and network port that stay alive even when the…
- Ilya MironovThe cryptographer who showed that differential privacy can leak through the least significant bits of a float, then helped…
- IMA (Linux Integrity Measurement)Linux Integrity Measurement Architecture. Kernel feature: hash all executed files + log to TPM. Remote attestation possible…
- Image (Container image)A packaged, immutable snapshot of an application + its dependencies — what you run a container from.
- Image digestA cryptographic hash (SHA-256) that uniquely and immutably identifies an exact container image. Unlike a tag (which can be…
- Image layerA container image is built from stacked, immutable layers — where each layer is the difference (diff) a build step added…
- Image processingManipulation of digital images — low level (pixel, filter, edge detection) or high level (object recognition, segmentation)…
- Image-based lighting (IBL)Lighting a scene with a picture — often a panorama of a real place — instead of a handful of point lights, so objects pick…
- ImageText and PolyTextX11's two ways of drawing text with the server's own fonts: with a background, or without one.
- ImageWriterApple's 1983 nine-pin dot-matrix printer, the default output for the Apple II and early Macintosh before laser took over.
- Imagination TechnologiesThe British PowerVR licensor whose graphics powered the Dreamcast and every early iPhone — until Apple decided to go it…
- Imaging drumThe light-sensitive cylinder in a laser printer where the page is drawn as electric charge before the toner sticks.
- imakeX11's own build system, which had the C preprocessor write Makefiles from an Imakefile: portable across every Unix and…
- IMAP (Internet Message Access Protocol)Protocol for reading email — keeps mail on the server (unlike the older POP3).
- IMEIThe phone's unique hardware number — fifteen digits identifying the handset, not the subscription.
- iMessageApple's encrypted messaging service — blue bubbles between iPhones, green when it falls back to SMS.
- imgixAn image CDN that crops, compresses and reformats images on the fly via URL parameters.
- ImlibRasterman's image library that loaded, scaled and dithered pictures into X pixmaps, carried Enlightenment and all of GNOME…
- Immediate mode GUIA UI approach where every widget is drawn and handled afresh each frame through direct function calls, with no lasting tree…
- Immersion coolingSubmerging whole servers in a non-conductive fluid. Sounds like a joke until rack density passes fifty kilowatts and air…
- ImmutabilityData that can't be changed after creation — to "change" something you create a new version.
- Immutable infrastructurePrinciple: never modify a server after deploy — build a new image, ship it, replace the old.
- IMP (Interface Message Processor)The fridge-sized minicomputer that sat at every ARPANET site and moved packets — effectively the world's first router.
- ImpacketPython library of clean implementations of Windows network protocols. The standard toolbox for everything done against…
- Impact printerUmbrella term for printers that form characters by striking an inked ribbon against paper with mechanical force.
- Imperative programmingParadigm: describe how a program should execute, step by step. Opposite: declarative. C, Java, Python, JavaScript are…
- ImpervaThe company that sold firewalls for web applications and databases before most people knew they needed one.
- ImphobiaBelgian PC diskmag from the early-to-mid 90s and one of the most widely read publications of the young PC scene.
- ImploderOne of the Amiga's early executable packers — it compressed programs so they unpacked themselves at launch.
- Import mapsA browser feature (<script type="importmap">) for mapping "bare name" imports (import x from "lodash") to actual URLs. It…
- Impossible differentialAn attack that exploits an input difference which can, with certainty, never produce a given output difference.
- ImpostorA billboard that replaces distant 3D geometry with a pre-rendered image pasted onto a single quad that turns to face the…
- Impulse responseA system's complete fingerprint: how it reacts to a single, infinitely short click.
- Impulse TrackerThe best-sounding DOS tracker — 64 channels, resonant filters and the IT format that effectively ended the tracker wars.
- IMSAIOne of the first Altair clones, an 8080-based kit that became the face of the home computer in the film WarGames.
- IMSIThe subscriber's unique identity in the mobile network, stored on the SIM — and the datum that makes IMSI catchers possible.
- In-app purchasePayment inside the app through the store's system — and the business model that made free apps the industry's most…
- In-context learning (ICL)When an LLM "learns" from examples in the prompt without changing its weights.
- in-totoOpen framework for supply chain integrity. Defines "links" — signed attestations about every pipeline step (who built, from…
- Incident (Security incident)A confirmed security event that has or could have a negative impact — not just "something weird".
- Incident postmortemA structured analysis after a serious operational incident: what happened, why, how it was resolved, and what should change…
- Incident response (IR)The process of handling an ongoing security incident — detect, contain, eradicate, learn.
- Inclusive cacheA cache policy where a lower level (e.g. L3) is guaranteed to contain everything in the higher levels (L1/L2) above it. It…
- INCR transfer (X11)The ICCCM's way of delivering a selection too big for a single property: in chunks, with a handshake per chunk and just as…
- Incremental plotterA plotter that can only take one step at a time in eight directions — the computer sends movement pulses, not coordinates.
- IND-CCA2Like IND-CPA, but the attacker may also ask a decryption oracle to open any ciphertext of its choice, except the challenge…
- IND-CPAAn encryption scheme is IND-CPA secure if an attacker cannot tell which of two chosen messages was encrypted, even with…
- Index (database)Data structure (usually a B-tree) that lets the database find rows without reading the whole table.
- Index bloatAn index taking three times the space it should, because deleted entries left sparsely filled pages that never get packed…
- Index bufferA buffer of integer indices into a vertex buffer, letting a mesh reuse each shared vertex once instead of duplicating it for…
- Index holeThe small hole near the hub of a floppy that a photocell reads once per revolution to know where the track begins.
- Index of coincidenceThe probability that two characters drawn at random from a text are the same — a single number that tells you whether a…
- Index registerA register whose value is added to an instruction's address, so one piece of code can sweep an entire array just by counting…
- Index-only scanWhen the database can answer the whole query from the index without touching the table. The fastest possible read: one tree…
- Indexed renderingVertices are stored once in a vertex buffer and reused through a separate list of indices, instead of being duplicated per…
- IndexedDBAn actual database built into the browser — can store hundreds of MB of structured data offline.
- Indicator of compromise (IoC)An observable artifact that suggests a breach has occurred — a file hash, an IP address, a domain name, a registry value, a…
- Indigo MagicSilicon Graphics' desktop for IRIX — Unix that looked as though someone had actually thought about how it should look.
- IndilinxThe Korean controller maker whose Barefoot chip made the early consumer SSDs fast enough to care about.
- Indirect drawA draw call whose vertex count, instance count and offsets are read from a GPU buffer instead of being passed by the CPU…
- Indirect syscallsJumping to the system call instruction inside ntdll rather than carrying your own, so the call stack looks normal. One move…
- Inductive headThe read/write head built on Faraday induction — a coil around a magnetic core that both writes and reads with the same…
- inertHTML attribute that makes an entire subtree inoperative: not clickable, not focusable, invisible to screen readers and…
- Inertia tensorThe 3×3 matrix describing how a rigid body's mass is distributed around its centre of mass — the rotational counterpart to…
- inetdThe Unix super-server: one process listening on every port, launching the right program only when someone connects.
- inewsThe program that took a freshly written Usenet post, filled in the mandatory headers and handed it to the local news server.
- InferenceActually running a trained ML model — send in input, get output. Opposite of training.
- Inference costCost to run an LLM on a query (not to train it). Dominated by memory bandwidth (every token requires reading full weights)…
- Inference-time scalingSpend more compute at inference (longer chain-of-thought, beam search, MCTS) instead of training a larger model. Made famous…
- InfineonSiemens's spun-off chipmaker, the world's largest in power semiconductors and a major supplier of security chips.
- InfineraThe optics company that squeezed a rack's worth of lasers and modulators onto a single indium phosphide chip.
- InfiniBandHigh-performance interconnect: 200-800 Gbps per port, ~600 ns latency. Standard in supercomputers + AI training clusters…
- Infinite loopA loop whose condition never turns false — either a serious bug or exactly what you wanted.
- Infinity CacheAMD's large on-chip cache on Radeon graphics cards (RDNA 2+), a kind of enormous L3 for the GPU. By capturing a lot of…
- Infinity EngineBioWare's isometric RPG engine from Baldur's Gate, which carried an entire generation of computer role-playing games.
- Infinity FabricAMD's internal interconnect fabric that ties together CPU core complexes (CCD), the memory controller, and I/O in the Zen…
- Inflection AIThe AI company behind the Pi chatbot, which raised more than a billion dollars and then effectively moved in with Microsoft…
- Influence mapA grid over the game world where each cell accumulates a value for who controls the area, smeared outward so that front…
- InfluencerA person who has built an audience on social media and is paid to recommend things to it. The occupation grew out of…
- InfluxDataThe company behind InfluxDB, which changed query languages and storage engines faster than most users could learn them.
- InfluxDBTime-series database — purpose-built for large volumes of time-stamped data (metrics, sensors, financial ticks).
- Info-MacA Macintosh mailing list and file archive, started at Stanford in 1984, that became the Mac world's main source of shareware.
- InfobipA Croatian company that sends half the world's login codes and delivery alerts from a small town in Istria.
- InfobloxThe company that turned DNS, DHCP and IP address management into a box you buy rather than a pile of scripts on an old Linux…
- InfocomThe pre-eminent publisher of text adventures, founded by MIT people and sunk by a database.
- InformaticaThe plumber behind thousands of data warehouses: software that moves, cleans and merges data between systems never meant to…
- InformixThe runner-up in the 1990s database wars, which beat Sybase, took on Oracle and then tripped over its own books.
- InfoseekEarly American search engine that Disney bought and folded into the Go.com portal.
- InfosysSeven engineers in Pune with borrowed seed money who proved software could be built on the other side of the planet.
- Infrastructure as Code (IaC)Defining and managing infrastructure — servers, networks, databases, cloud resources — with machine-readable configuration…
- IngenicoFrench payment-terminal maker and Verifone's perennial opposite number; in Europe, usually the one on the counter.
- Ingram MicroThe world's largest IT wholesaler — the company between vendor and reseller that most people have never heard of.
- IngressKubernetes resource that controls external HTTP traffic coming into the cluster.
- Ingress controllerThe component that routes incoming HTTP(S) traffic from the outside in to the right service in a Kubernetes cluster, based…
- Ingrid VerbauwhedeBelgian hardware security researcher at KU Leuven who works on building cryptography into silicon without the physics…
- InheritanceA class "inherits" properties and methods from another: class Dog extends Animal.
- INI (configuration format)Plain-text configuration format: bracketed sections, key=value pairs. No official standard — just an MS-DOS-era artifact…
- Iñigo QuílezSpanish graphics programmer, "iq" on the scene, who carried demoscene procedural graphics into the wider industry.
- Init containerA Kubernetes container that runs to completion before the main container starts. Use: wait for dependencies (DB ready), DB…
- Init systemThe first process the kernel starts, and ancestor of everything else — PID 1.
- Initial ordersThirty-one instructions burned into telephone switches — the small piece of start-up code that taught EDSAC to read in its…
- Initialization vectorThe non-secret starting value that makes the same message encrypt to different ciphertext twice running.
- Initiating unit (ENIAC)The panel with the start button: it cleared the machine, brought the supplies up in the right order and fired the first…
- initramfsA small temporary root filesystem the boot loader loads into memory alongside the kernel. It exists to solve a…
- ink (inkle)A markup language for branching text in which the script reads like prose and the logic takes up as few characters as…
- Ink cartridgeA replaceable container of liquid ink for an inkjet printer, often costlier per millilitre than you care to work out.
- Inkjet printerPrinter that forms characters from microscopic ink droplets sprayed at the paper without touching it.
- InkscapeOpen-source vector editor — SVG as the native format (not converted, not abstracted). The Adobe Illustrator alternative.
- InktomiThe search engine behind other people's search boxes, and proof that the web could be indexed on a pile of cheap Unix boxes…
- InmosBritain's state-backed attempt at a homegrown chip industry, which gave the world the transputer and was then sold on twice.
- INNInterNetNews: the news server built for machines that stayed connected, which became Usenet's default once the UUCP era…
- InnoDBMySQL's and MariaDB's default storage engine, and the reason MySQL can be called a real database. Written by Heikki Tuuri…
- InodeThe structure holding everything about a file except its name — owner, permissions, size, timestamps and where the blocks…
- INP (Interaction to Next Paint)Interaction to Next Paint — Web Vitals metric that replaced FID in March 2024. Measures the worst interaction latency…
- Input bufferingStoring a button press for a short while so the action still fires even if it was pressed slightly too early.
- Input delayThe netcode technique that deliberately holds back your own button presses by a few frames so the opponent's arrive in time…
- Input lagThe time between pressing a button and seeing the result on screen, summed across every link in the chain.
- Input remappingLetting players reassign which physical buttons trigger which in-game actions, decoupling the game's logic from fixed…
- InputOnly windowX11's invisible window class: a window with no pixels whose only job is to receive mouse and keyboard events over a region.
- Insecure deserializationVulnerability where an application deserialises untrusted data and ends up executing attacker-controlled object…
- Insert effectAn effect patched directly into a channel's signal path, so the entire signal passes through it.
- Insomniac GamesThe studio behind Spyro, Ratchet & Clank and Sony's Spider-Man — technically driven and prolific to a rare degree.
- InspIRCdAn IRC server written from scratch in C++, without inheriting a single line from Oikarinen's original.
- InspurChina's largest server builder, a state-adjacent colossus that ships racks by the lorry-load — and landed on the US…
- InstagramPhoto-sharing platform launched in 2010 by Kevin Systrom and Mike Krieger, acquired by Facebook in 2012 for USD 1 billion…
- Instagram bio150-character text on Instagram profile. Valuable real estate — the only clickable link on the profile lives there. Drives…
- Instagram Business AccountAccount type for companies/creators. Three tiers: Personal, Creator, Business. Business gets analytics (Insights), ad…
- Instagram ReelsInstagram's TikTok clone — 15-90 sec vertical videos. Launched globally 2020 after TikTok tariff drama. Algorithmically…
- Instagram StoriesInstagram feature launched 2016 — direct copy of Snapchat Stories. 24-hour ephemeral posts. Kevin Systrom openly admitted…
- InstanaApplication Performance Monitoring platform. Pål Erik Sjåtil founded it in 2015 in Germany. IBM acquired in 2020. Strong on…
- InstanceA concrete occurrence of something general — in OOP a runtime-created copy of a class; in cloud a running VM or container…
- Instance blockUser-level feature: block all users from a specific instance with one click. Mastodon "domain block" — all current + future…
- Instruct modelAn LLM fine-tuned to follow instructions (answer questions, do what you tell it) instead of just continuing text.
- Instruction fetchThe first step in the CPU's pipeline, where instructions are fetched from memory (the instruction cache) to be fed into the…
- Instruction tuningFine-tuning a raw language model on a large set of (instruction, answer) pairs so it learns to follow instructions instead…
- IntegerWhole number without decimals — int, int32, int64, BigInt.
- Integer scalingUpscaling a low-resolution image by whole-number factors — 2×, 3×, … — so every source pixel becomes an identical square.
- Integral attackAn attack that exploits sets of inputs whose intermediate sums cancel to zero in a cipher with reduced rounds.
- IntegraphA mechanical instrument that, traced along a curve, draws its integral — the whole antiderivative, not just a single area.
- Integration testA test that exercises multiple components together — often with a real database or mock server.
- IntelCreated the microprocessor, owned the personal computer for thirty years, and then lost the lead in manufacturing technology.
- Intel ArcIntel's discrete GPU line. Launched 2022 (Alchemist), Battlemage gen 2 launched 2024. Despite poor driver reviews at launch…
- Intel Foundry (IFS)Intel's comeback strategy to become a foundry for others (not just for its own chips). Pat Gelsinger launched in 2021; it…
- Intel High Definition AudioThe successor to AC'97, launched by Intel in 2004 under the codename Azalia — the interface behind almost every built-in…
- Intel SGXIntel Software Guard Extensions — hardware-isolated TEE (Trusted Execution Environment). Apps run in an "enclave" where even…
- IntellexaThe consortium behind the Predator spyware — a loosely stitched group of companies across several EU countries, sanctioned…
- IntelliJ IDEAJetBrains' Java IDE, released in 2001. It was first to index the whole project and understand the code semantically, which…
- IntentiaThe Swedish ERP company behind Movex, now called Infor M3 and still running warehouses and production lines across the…
- Inter-App AudioApple's first mechanism for passing audio and MIDI between music apps on iOS, introduced in iOS 7 and superseded by AUv3.
- Inter-block gapThe blank stretch of tape between two data blocks, long enough for a start-stop transport to brake and get back up to speed.
- Inter-record gap (IRG)The blank stretch of tape between two records that gives the drive room to speed up and slow down between reads.
- Interaction to Next Paint (INP)A Core Web Vital that measures how quickly the page visually responds to the user's interactions (clicks, taps, key presses)…
- InterBBSDoor games in which several BBSes shared one game world by mailing game data to each other overnight.
- INTERCALA language whose stated design goal was to resemble no other language then in existence.
- Interchange feeThe fee an acquirer pays the card issuer on every card purchase, ultimately paid by the merchant.
- IntercomThe Irish SaaS that popularised the chat bubble in the bottom-right corner and turned it into the default interface for…
- Interest managementThe practice of sending each player only the parts of the game state relevant to them, so bandwidth doesn't scale with the…
- InterfaceA contract describing which methods a class must implement, without specifying how.
- Interface BuilderNeXT's tool for drawing interfaces and wiring them to code by dragging lines between objects — saved as finished objects…
- Interference effectA demo effect where two moving radial gradients are added together so that moiré patterns of rings drift across the screen.
- IntergraphThe Huntsville company that sold CAD and GIS workstations, then sued Intel – and won.
- Interlace flickerThe visible shimmer that appeared when the Amiga doubled its vertical resolution by drawing every other line each frame…
- InterlacingTransmitting every other scan line at a time to halve the bandwidth — analogue television's clever cheat, and a plague in…
- Interleaved 2 of 5A numeric barcode in which every other digit is carried in the bars and every other one in the spaces — hence "interleaved."
- Interleaved audioA layout for multichannel audio where samples from each channel alternate, left-right-left-right, rather than living in a…
- Interlisp-DXerox PARC's Lisp environment for the D-machines, from around 1981, in which editor, debugger and windows all lived inside…
- IntermecThe company from Everett, Washington that invented Code 39 and then gave it away.
- Intermodulation distortion (IMD)New tones created when two frequencies pass through the same nonlinear circuit and mix into sums and differences that were…
- IntermudProtocols that linked independent MUD servers so players could chat and send messages between worlds.
- InternetGlobal network of networks running the TCP/IP protocols. Roots in ARPANET 1969, commercialized 1995, ~5.5 billion users in…
- Internet exchange (IX)A physical location (usually a pair of large switches in a data center) where many networks — operators, content providers…
- Internet Explorer (IE)Microsoft's browser 1995–2022. Dominated the browser market 1999–2010 (peak 95% market share). IE6 is infamous as the worst…
- Internet HuntA monthly scavenger hunt on the early internet, where the questions were easy and the hard part was working out where the…
- Internet Security SystemsISS, the Atlanta firm that turned vulnerability scanning into a product and X-Force into a brand.
- Internet ToasterA toaster John Romkey controlled over the network with SNMP at Interop 1990, because a dare required it.
- InterNICThe NSF's name for the internet's shared registry from 1993 to 1998 — where you went for a .com domain, and where domains…
- InterplayThe Californian publisher that created Fallout and later had to sell it to pay the bills.
- InterpolationLetting expressions be evaluated inside a string literal — f"Hi {name}" instead of gluing pieces together by hand.
- Interpolation attackAn attack that writes a cipher down as a polynomial, provided its algebraic degree is low enough.
- InterposerThe slab of silicon under the chips whose only job is running wires — denser than a circuit board can manage and cheaper…
- InterpressXerox's 1982 page description language — technically ahead of its time, but it was the frustration around it that spilled…
- InterpreterProgram that runs source code directly without compiling to machine code first.
- InterruptSignal to the CPU to pause current work and handle something urgent — keypress, packet from NIC, timer tick.
- Interrupt (IRQ)A signal from hardware (or software) that interrupts the CPU in the middle of what it's doing to notify it that an event…
- Intersection ObserverA web API that asynchronously notifies when an element enters (or leaves) the viewport or another container. It replaces…
- IntersilA much-traded chipmaker that managed to build both a PDP-8 on a chip and early Wi-Fi.
- InterViewsAn object-oriented C++ toolkit for X from Stanford, remembered less for its applications than for the design patterns it…
- Intro diskAn electronic magazine that began with a short programmed intro sequence before loading the articles.
- IntuitThe company that turned household finance and the American tax return into a subscription.
- Intuition (Amiga)The Amiga's windowing and interface system from 1985 — the layer that drew windows, menus and buttons far beneath the…
- Invalid curve attackAn attack on elliptic-curve key exchange that works when a server accepts points that do not lie on the intended curve.
- InvariantProperty that's always true in a specific part of the code. Loop invariant holds at every iteration. Class invariant holds…
- Invariant subspace attackAn attack that finds a set of plaintexts which the cipher, under certain keys, maps onto itself round after round.
- InventecTaiwanese ODM that has quietly built vast numbers of laptops and servers for other people's brands.
- Inverse kinematicsWorking out which joint angles are needed for a hand or foot to reach a given point — the reverse of ordinary kinematics.
- Inversion of ControlPrinciple where the flow of control is inverted — instead of your code calling a library, the framework calls your code. The…
- Invincibility framesA brief window after taking a hit — or during a dodge — when the character cannot be hurt again, measured in frames.
- Invisible salamandersAn attack in which one AES-GCM ciphertext decrypts to two different images depending on the key, which fooled Facebook…
- InVisionThe 2010s default for showing a client a clickable prototype — until Figma made the whole in-between step unnecessary and…
- InvitroAn invitation intro: a demo or intro whose entire job is to advertise an upcoming demoparty.
- io_uringThe Linux kernel's modern async I/O interface — two ring buffers (submission + completion) shared between kernel and…
- IoCs (Indicators of Compromise)Technical evidence that a system is compromised — file hashes, IP addresses, domains, registry keys.
- IomegaThe Utah company that sold removable storage to a generation that had outgrown the floppy but couldn't afford a second hard…
- Iomega JazIomega's 1 GB cartridge built around real hard-disk platters — fast and roomy, but expensive and fragile.
- IOMMU (VT-d / AMD-Vi)A Memory Management Unit for I/O devices — translates device DMA addresses to virtual ones, enabling PCI passthrough and DMA…
- IonAn early tiling window manager built on static frames and tabs, remembered mostly for its licence.
- Ion StormThe Texas studio that shipped one of gaming's most notorious flops and one of its finest games in the same year.
- IonicThe UI library that makes a web app look like a mobile app — buttons, lists and transitions imitating iOS and Android.
- IONOSEurope's largest web host, spun out of Germany's 1&1.
- IonQThe first pure-play quantum computing company on the stock market — ions for qubits and a valuation well ahead of revenue.
- IOPSInput/output operations per second — storage's most quoted performance figure and its easiest to mislead with.
- iOSApple's mobile operating system — the same Unix kernel as macOS, but with a considerably tighter fence around it.
- IoT (Internet of Things)Network-connected physical devices — sensors, actuators, cameras, lights, cars. Kevin Ashton coined the term in 1999.
- IP addressNumeric identifier for a device on a TCP/IP network. IPv4: 32 bits (4.3 billion, practically exhausted). IPv6: 128 bits (340…
- IP aliasingAssign multiple IP addresses to the same physical interface. Classic: eth0:0, eth0:1 (ifconfig syntax). Modern Linux: ip…
- IPAM (IP Address Management)A system for tracking which IP addresses and subnets are allocated where.
- iPAQCompaq's handheld from 2000 that made the Pocket PC popular before the smartphone ate the whole category.
- IPC (Instructions Per Cycle)Instructions Per Clock — a CPU performance metric: how many instructions retire per clock cycle on average. Modern CPUs…
- IPC (Inter-Process Communication)The umbrella term for how processes talk to each other despite having separate, isolated memory.
- IPC (inter-process)Inter-Process Communication — mechanisms for exchanging data between processes. UNIX mechanisms: pipes, sockets, shared…
- IPDSIBM's bidirectional printer protocol, where the host drives every page and gets a receipt that it actually printed.
- iperfThe standard tool for measuring actual throughput between two machines. Run iperf3 -s on one end and iperf3 -c server on the…
- IPFIXIP Flow Information Export — IETF standard (RFC 7011, 2013) based on Cisco's NetFlow v9. Template-based format that lets…
- IPFS (InterPlanetary File System)Peer-to-peer protocol for content-addressed storage, started by Juan Benet (Protocol Labs) in 2015. You ask for what you…
- IPLThe world's first AI language, which introduced the linked list two years before LISP made the idea famous.
- iPlug2A permissively licensed C++ framework for audio plugins — the small alternative to JUCE, with one foot in the browser.
- IPMI (Intelligent Platform Management Interface)"Lights-out management" for servers — remote power-on, remote console, BIOS access, even when the OS is dead.
- IPPThe network protocol that turns a printer into an HTTP address you send jobs to and query.
- IPP EverywhereThe standard that makes printer drivers obsolete: the printer describes itself over IPP and accepts well-defined standard…
- IPS panel (In-Plane Switching)LCD panel type with excellent viewing angles and colour accuracy — the standard for "good" displays.
- IPsecClassic VPN/tunneling protocol — encrypts IP packets between two gateways.
- ipsetKernel structure that stores tens of thousands of addresses in a hash table so iptables can match the whole set with one…
- iptablesLinux's classic firewall tool — rules for which packets are accepted, dropped or masqueraded.
- IPv4The classic IP version — 32-bit addresses, ~4.3 billion in total. Officially exhausted since 2011.
- IPv4 exhaustionOut of IPv4 addresses — IANA handed out the last /8 blocks in 2011, the RIRs have emptied their pools ever since.
- IPv6The successor to IPv4 — 128-bit addresses and 340 sextillion addresses.
- ipvlanThe same idea as macvlan but without individual MAC addresses: all virtual interfaces share the physical card's address and…
- IPVS (IP Virtual Server)Transport-layer load balancing built into the Linux kernel, the core of the LVS project since 1998. It spreads incoming…
- Ira WinklerFormer NSA analyst who built a career on showing how easily companies fool themselves.
- IRC (Internet Relay Chat)Real-time chat protocol from 1988 (Jarkko Oikarinen, Oulu, Finland) — text-based, plaintext, channels prefixed with #, still…
- IRC operatorThe user holding the keys to the IRC server itself rather than to a single channel — IRCop, in the vernacular.
- IRCAMThe Paris institute for acoustics and computer music that the French state gave Pierre Boulez, and the root of a surprising…
- ircdThe IRC server program — both Jarkko Oikarinen's original from 1988 and the family of forks every network ended up running…
- ircd-hybridThe IRC server EFnet was built on from the late 1990s, and the ancestor of a whole family of servers.
- ircIIThe text-mode IRC client most 1990s Unix users chatted through, and the ancestor of a whole family.
- IRCnetThe European half of IRC's great split of 1996, when EFnet broke apart over how its servers should be run.
- ircuUndernet's own branch of the IRC server code, with a server protocol that renamed everyone as short numbers to save…
- IRCv3Modernization of the IRC protocol (RFC 1459 from 1993). The IRCv3 working group has been active since 2014. Adds capability…
- IRCXMicrosoft's 1998 extension of IRC, used in MSN Chat and Exchange.
- IrDAThe wireless standard of the nineties: an infrared port demanding clear line of sight and about a metre of range — made…
- Irit DinurIsraeli theoretical computer scientist whose 2003 reconstruction attack made differential privacy a necessity.
- IRQThe signal from a hardware device saying "I need attention now" — an interrupt request.
- IRQ coalescingNIC feature: batch several packets per interrupt instead of one interrupt per packet. 10 GbE+ with small packets = millions…
- IRQ loaderC64 loader that pulls data off the disk in the background while music and effects keep running.
- Irradiance mapA precomputed texture that stores, for every direction, how much diffuse light arrives from it, so indirect lighting can be…
- IrrlichtA lightweight C++ 3D engine from the early 2000s — the trim cousin of OGRE.
- IrssiA terminal IRC client written by Timo Sirainen in 1999. It replaced ircII and BitchX as the default choice and has remained…
- IS-ISIntermediate System to Intermediate System — a link-state routing protocol (IGP) in the same family as OSPF, but with roots…
- ISA (instruction set architecture)Instruction Set Architecture — the "contract" between hardware and software: which instructions a processor understands…
- IsilonThe Seattle company that built NAS clusters where you add capacity by sliding in another node and the filesystem simply…
- Island architectureStatic HTML with small "islands" of interactive components — not the whole page like an SPA.
- Island of KesmaiOne of the first commercial multiplayer role-playing games, played over CompuServe by the hour.
- Islands ArchitectureWeb architecture: static page + isolated interactive "islands". Coined by Jason Miller 2020 ("Islands Architecture" blog…
- ISO 10126 paddingA padding scheme that fills the gap with random bytes and records the padding length in the final byte.
- ISO 20022The common standard for financial messages, which has replaced the banks' fixed-width text formats with XML and rich…
- ISO 27001The international standard for information security management systems (ISMS).
- ISO 4217The standard for currency codes – SEK, EUR, USD – along with a numeric code and the number of decimal places.
- ISO 8583The terse binary format that carries almost every card transaction on earth between terminal, acquirer, network and issuer.
- ISO 9660The cross-platform file-system standard for CD-ROM that let the same disc be read on DOS, Mac and Unix.
- ISO sceneThe branch of the warez scene that releases whole disc images — games and software in the original — as opposed to the rip…
- ISO/IEC 7816-4 paddingA padding scheme that appends the byte 0x80 followed by zeros until the block is full.
- ISOCELLSamsung's camera sensors, where each pixel is walled off so light can't leak into its neighbour.
- Isolation levelSQL standard levels for concurrency isolation: READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ, SERIALIZABLE. Trade-off…
- Isolation levelsVarying strength of guarantees for how transactions see each other's data — Read Uncommitted, Read Committed, Repeatable…
- Isometric projectionA parallel projection where the three axes are equally foreshortened — fake 3D with no perspective and no vanishing point.
- IsovalentThe company that turned eBPF into a commercial networking layer for Kubernetes, then sold itself to the networking giant it…
- ISP (Internet Service Provider)The company that connects you to the internet — Comcast, AT&T, Telia, BT, etc.
- ISRCTwelve characters that identify a specific recording, not the song, and decide who gets paid when it is played.
- Issue widthHow many instructions (or micro-operations) a CPU core can issue to its execution units per clock cycle. An "8-wide" core…
- IstioService mesh for Kubernetes — Google + IBM + Lyft, 2017. Routes traffic between microservices with Envoy as sidecar proxy…
- IT formatThe module format from Impulse Tracker, the last big step in the tracker family after MOD, XM and S3M.
- ITA2The five-bit code the teleprinter world actually ran on — Baudot's idea, Murray's rework, and the thing Colossus attacked…
- Itai DinurIsraeli cryptanalyst who, with Adi Shamir, showed that even a cipher treated as a black box leaks algebraic structure.
- ItaniumIntel and HP's 64-bit architecture from 2001 that was meant to bury x86 and instead earned the nickname Itanic.
- itch.ioAn open marketplace for indie games where the developer sets the price, the revenue split — and even zero.
- IteratorAn object that produces values one at a time — the basis for loops over collections.
- Iterator (Rust)Rust's fundamental sequence abstraction. Trait with one method: fn next(&mut self) -> Option<Item>. Lazy by default…
- iTerm2The terminal emulator nearly every macOS developer installs first. Free and open source, maintained by George Nachman since…
- Itsik MantinIsraeli cryptographer who spent much of a career demonstrating that RC4 was more broken than anyone cared to admit.
- Ivan DamgårdDanish cryptographer at Aarhus University whose name is on the construction behind MD5, SHA-1 and SHA-2 — and who has mostly…
- Ivan KrstićCroatian-born security architect who first designed security for children's laptops without user accounts, then for a…
- Ivan RistićSerbian-British developer behind ModSecurity and SSL Labs, the tool that gave every HTTPS server a grade from A to F.
- Ivan SutherlandThe founder of computer graphics: wrote Sketchpad as a graduate student and built the first head-mounted display five years…
- IvantiA roll-up of IT management tools that became best known for its VPN appliances and their vulnerabilities.
- IVFFlat (Inverted File, Flat)Inverted File with Flat compression — a cluster-based algorithm for approximate vector search. It divides the vector space…
- IvoryA polished Mastodon client for iOS and Mac from Tapbots — the same studio that made the acclaimed Twitter app Tweetbot. It…
- iWARPRDMA on top of ordinary TCP/IP. The competitor to RoCE, and the variant that doesn't require rebuilding your network to…
- iXMLAn open metadata standard that embeds XML in audio files so the production notes travel with the sound.
- iZettleThe Stockholm startup that turned a phone into a card terminal for flea markets, hairdressers and coffee carts.
- iZotope RXA restoration suite that scrubs recordings clean of noise, clicks, hum and coughs — post-production's default fixer.
J
- J. Presper EckertThe engineer who was twenty-four when he took charge of ENIAC's electronics, and who thirty years later lost the patent on…
- JabilOne of the world's largest electronics manufacturers, whose name almost no consumer has ever seen on a product.
- JACKJACK Audio Connection Kit — the pro-audio sound server that lets any program's inputs and outputs be patched into any other…
- Jack GoodTuring's statistician at Bletchley, who later coined "intelligence explosion" and advised Kubrick on HAL 9000.
- JackTripStanford software that sends uncompressed multichannel audio over the internet with low enough delay for musicians in…
- Jacob AppelbaumAmerican security researcher and Tor developer who became one of the faces of the 2010s surveillance debate – and then left…
- Jacob Hoffman-AndrewsThe EFF technologist who wrote a good share of the certificate authority code behind Let's Encrypt.
- Jacob PalmeSwedish computer scientist who wrote the KOM conferencing system in 1978 and later helped standardise email formats at the…
- Jacobian IKAn inverse-kinematics method that uses the Jacobian matrix — how joints affect the end effector's motion — to iterate toward…
- Jacquard loomThe loom that read its pattern from punched cards — the first machine driven by interchangeable instructions.
- Jacques PatarinFrench cryptographer who first broke Matsumoto–Imai and then invented the multivariate schemes – HFE and Oil and Vinegar –…
- Jacques SternFrench cryptographer who built the ENS crypto group and was as good at breaking schemes as at proving them.
- JaegerDistributed tracing platform — Uber 2015, CNCF graduated 2019. Tracks a request across dozens of microservices and…
- JailbreakTricking an LLM into bypassing its safety rules — "DAN" (Do Anything Now), "roleplay as...", ciphered instructions.
- Jailbreak (LLM)Tricking an LLM into bypassing its own safety guards and doing what it's trained to refuse — via clever prompts: role-play…
- Jake DavisThe teenager from Shetland who, as Topiary, wrote LulzSec's press releases and ran its Twitter account in the summer of 2011.
- Jake WilliamsEx-NSA hacker turned incident responder and teacher — whom the Shadow Brokers publicly outed in 2017.
- JAM (message base)An open file format for storing BBS messages, with one set of files per conference instead of one shared giant database.
- James AspnesThe grad student who wrote TinyMUD in a few weeks in 1989 and then became a professor of something else entirely.
- James BamfordThe journalist who wrote the first major book about the NSA at a time when the agency barely admitted to existing.
- James EllisGCHQ cryptographer who showed in 1970 that public-key encryption was possible, and died weeks before he was allowed to say…
- James ForshawBritish researcher who finds holes in Windows faster than most people at Microsoft can read the reports.
- James GoslingLed the work on Java at Sun — the language meant to run set-top boxes that instead took over enterprise servers.
- James MasseyAmerican information theorist in Zurich who gave the world the Berlekamp–Massey algorithm and, with a PhD student, the IDEA…
- James MickensHarvard computer scientist who wrote the funniest, and possibly most quoted, pieces on why security research so often misses…
- James P. AndersonAmerican consultant whose two reports, in 1972 and 1980, laid the groundwork for both secure operating systems and intrusion…
- James PowersThe engineer who built the Census Bureau its own tabulating machines when Hollerith's rates got steep — and was then allowed…
- JamfThe company IT departments call once the leadership team decides everyone gets a Mac.
- Jamie ButlerThe rootkit researcher behind FU and DKOM, which hid processes by simply removing them from the kernel's own bookkeeping.
- JAMstackArchitecture for modern sites: JavaScript + APIs + pre-built Markup, served via CDN.
- JamulusOpen-source software for playing music together over the internet, with a server that mixes everyone and sends it back.
- Jan CamenischSwiss cryptographer behind Idemix, IBM's system for proving facts about an identity without handing over the identity.
- Jan de WitDutch 20-year-old who released the Anna Kournikova worm in February 2001, assembled in an afternoon with an off-the-shelf…
- Jan Krissler (starbug)The CCC hacker who has made fooling biometric locks a recurring public demonstration, usually with wood glue, a laser…
- JANETThe UK academic network, which spent seven years writing its addresses backwards compared with everyone else.
- Jann HornThe Project Zero researcher who found both Spectre and Meltdown on his own in 2017, in parallel with several academic teams.
- Jargon FileHacker culture's own dictionary — a text file that drifted between Stanford and MIT for fifteen years before becoming a book.
- Jarkko OikarinenThe Finnish student who wrote IRC over a summer in Oulu in 1988.
- JasmineThe JavaScript testing framework that established the describe/it syntax everyone else copied afterwards.
- Jason A. DonenfeldThe developer who gave Linux a VPN in a few thousand lines of code, in a field where the competition was measured in…
- Jason ScottAmerican archivist and documentary maker, the man behind textfiles.com and one of the most tireless voices for digital…
- JavaStatically typed OOP language on the JVM — James Gosling et al. (Sun Microsystems, 1995). "Write once, run anywhere" was the…
- Java Desktop SystemSun's GNOME-based desktop from 2003, sold as a corporate alternative to Windows and named after Java despite containing…
- JavaScriptBrendan Eich wrote the first version in 10 days (1995) under the name Mocha → LiveScript → JavaScript. Today the web's only…
- JAXGoogle's ML framework — NumPy API plus automatic differentiation, JIT compilation via XLA, and first-class TPU support.
- Jay ForresterThe engineer behind Whirlwind who gave the computer a memory it could trust — then changed fields entirely.
- Jay FreemanThe developer known as saurik, who built Cydia, the app store for jailbroken iPhones, and with it the plumbing for an entire…
- Jay RadcliffeThe diabetic researcher who hacked his own insulin pump and got manufacturers to pay attention.
- Jaya BalooSecurity chief who asked early and loudly what quantum computers would do to telecom encryption.
- Jayson StreetAmerican security consultant paid to stroll into banks and offices and see how far he gets before anyone asks who he is.
- JBODJust a Bunch Of Disks — external disk chassis (12-90+ disks) that exposes individual disks without built-in RAID. Host…
- JCH EditorDane Jens-Christian Huus's music editor for the C64's SID chip, the backbone of the group Vibrants and one of the scene's…
- JCLThe IBM mainframe language for describing a batch job — notorious for letting one misplaced character sink an entire run.
- JD EdwardsDenver ERP vendor whose software made IBM midrange machines run the books, warehouses and factory floors of thousands of…
- JD.comChina's second-largest e-commerce company (after Alibaba) — focus on authentic goods + own logistics. "It's not Taobao" was…
- Jean BartikOne of ENIAC's six original programmers, and the one who led the rebuild that turned the machine into a stored-program…
- Jean HoerniThe physicist among the traitorous eight who invented the planar process — the technique that made the integrated circuit…
- Jean-Jacques QuisquaterBelgian cryptographer who made zero-knowledge proofs simple enough for children, light enough for smart cards — and who…
- Jean-Philippe AumassonSwiss-based French cryptographer behind the BLAKE hash family, SipHash and the password competition that gave the world…
- Jeanson AnchetaCalifornian botnet operator who in 2006 became the first person in the US convicted for renting out hijacked computers.
- Jeff ForristalAs rain.forest.puppy he described SQL injection in Phrack in 1998 — a bug that still tops the charts.
- Jeff MossFounder of DEF CON and Black Hat, the two conferences that make Las Vegas the world's densest gathering of hackers every…
- Jeff SchillerThe MIT network manager who made PGP legally downloadable in the US and spent a decade as the IETF's top security official.
- Jeff WilliamsAmerican application-security figure who wrote the first OWASP Top 10 and chaired OWASP for years.
- Jefferson diskThirty-six wooden disks on an axle, each bearing a scrambled alphabet. Invented by a future president, forgotten, and…
- Jeffrey HoffsteinAmerican number theorist who, with two colleagues, invented NTRU – practical lattice cryptography decades before anyone…
- Jeffrey Lee ParsonMinnesota teenager convicted over a variant of the Blaster worm, while the author of the original was never found.
- JekyllThe static site generator that made the concept popular. Written in Ruby in 2008 by Tom Preston-Werner, one of GitHub's…
- Jen EasterlyCISA director from 2021 to 2025 who tried to shift responsibility for security from users to software vendors.
- JenkinsThe veteran of CI/CD servers — open source, plugin-based, runs almost anything.
- Jennifer GranickAmerican lawyer who made a career of defending hackers and security researchers and of scrutinising government surveillance.
- Jens GrothDanish cryptographer whose Groth16 is the shortest pairing-based zero-knowledge proof in wide use – three group elements…
- Jens SteubeGerman developer behind hashcat, the tool that made the graphics card standard kit for password cracking.
- Jensen HuangHas led Nvidia since its founding in 1993 — unusually long for a CEO, and through a bet that looked unjustified for a decade.
- Jeremi GosneyThe password cracker who in 2012 strung together 25 graphics cards and put an end to the idea that eight-character Windows…
- Jeremiah GrossmanFounder of WhiteHat Security and one of the two people who named clickjacking.
- Jeremy HammondThe Chicago hacktivist who emptied the intelligence firm Stratfor of its email — onto a server the FBI's own informant had…
- Jeroen TelThe Dutchman whose SID tunes sounded impossibly rich — digi drums and hard-restart tricks that pushed the C64's sound chip…
- Jerome SaltzerMIT professor whose eight design principles from 1975 still turn up in almost every security review.
- Jerry YangTaiwan-born engineer who co-founded Yahoo with David Filo in 1994 — and in 2008 turned down Microsoft's $44 billion offer.
- Jerzy RóżyckiThe youngest of the Polish Enigma trio; inventor of the clock method, drowned in 1942 on his way home from North Africa.
- Jeskola BuzzA modular tracker for Windows from 1997, where synths and effects are wired together with on-screen cables.
- Jesper KydDanish composer who went from the Amiga demoscene to scoring Hitman and Assassin's Creed.
- JestFacebook's all-in-one test runner — popularised snapshot testing, ships with assertions, mocking, coverage.
- JetBrainsBuilds development environments that actually understand the code — and created the Kotlin language along the way.
- JetDirectHP's network card and print server that gave a printer its own IP address instead of hanging off a computer's parallel port.
- JetonCounting tokens shifted across a ruled table to add in Roman numerals, before pen-and-paper arithmetic took over Europe.
- Jetpack ComposeGoogle's declarative UI toolkit for Android — describe what the view should look like for a given state, not how to change…
- JetstreamBluesky firehose simplifier: WebSocket stream of all public posts/likes/follows as JSON. Launched 2024 as developer-friendly…
- Jetstream (Bluesky)A lightweight, JSON-based version of Bluesky's firehose. The raw firehose is binary (CBOR/CAR) and heavy; Jetstream delivers…
- JFrogIsraeli company that turned the storeroom for built binaries into a product category of its own.
- JHA SHA-3 finalist from Singapore, built to be fast without table lookups.
- JHipsterGenerator platform for full-stack Spring Boot + Angular/React/Vue applications. Produces production-ready scaffolding with…
- JiffyDOSA ROM swap from CMD (1989) that made Commodore's notoriously slow disk drive up to twenty times faster.
- Jiggle physicsProcedural secondary motion on bones the animator never hand-animated — hair, ponytails, antennae, cloth — that lags behind…
- Jill PipherAmerican mathematician at Brown University and one of NTRU's three inventors – whose main field is harmonic analysis, not…
- Jim BellCypherpunk who followed crypto-anarchy to its logical and deeply unpleasant conclusion in the essay "Assassination Politics".
- Jim BidzosThe businessman who turned the RSA patent into a company, started RSA Conference and co-founded VeriSign.
- Jim EllisThe other Duke graduate student behind Usenet, who in 1979 wanted to give Unix people without a defence contract something…
- Jim GettysCo-creator of X and author of Xlib, who went on to edit HTTP/1.1, run software at OLPC and give bufferbloat its name.
- Jim GilloglyThe computer scientist who solved three quarters of Kryptos with a computer — and showed the Beale treasure is almost…
- Jinja (Jinja2)Python's dominant template engine. Written by Armin Ronacher (2008), the same person who made Flask. {{ variable }} for…
- Jintai DingThe mathematician behind the Rainbow signature scheme and an early key exchange built on ring-LWE.
- JIT (Just-In-Time compiler)Compile code to machine code while the program runs — start interpreted, compile the hot parts.
- JIT accessJust-In-Time access — granting elevated permissions only when they're actually needed and only for a limited time, instead…
- JitsiOpen source video-conferencing stack. Launched 2003. Owned by 8x8 since 2018. Jitsi Meet (client) + Jitsi Videobridge (SFU)…
- JitterThe variation in latency — packets arrive at different speeds, not always the same.
- Jitter (audio)Tiny timing errors in the sample clock, so each sample is captured or played back slightly early or late.
- jMonkeyEngineThe longest-lived 3D game engine for Java — open, BSD-licensed, and proof that you can in fact write 3D games with a garbage…
- JN-25The Imperial Japanese Navy's main wartime code — a codebook wrapped in an additive cipher, and the reason the US ambush at…
- Jo Van BulckBelgian researcher who has spent his career showing that Intel's SGX enclaves keep secrets rather less well than the box…
- Joan ClarkeOne of the few women in a senior role at Bletchley Park — and the bureaucracy had no idea what to call her.
- Joan DaemenBelgian cryptographer who co-designed Rijndael and later Keccak, which became SHA-3.
- Joan FeigenbaumAmerican computer scientist who, with Matt Blaze, founded the field of trust management.
- Joanna RutkowskaPolish security researcher who showed how a hypervisor could be the perfect rootkit — then built an operating system on the…
- Job (K8s)A Kubernetes object for a task that should run to completion and then finish — a batch process, a migration, a one-off…
- Job schedulingSystems for running tasks later or on a schedule — beyond simple cron jobs.
- Job systemAn engine scheduler that breaks a frame into small jobs run across a thread pool with dependencies, so every CPU core stays…
- Jochen HippelGerman composer, known as Mad Max, who made the Atari ST's meagre sound chip sound like something else entirely.
- Joe GrandHardware hacker and the youngest member of L0pht, who these days breaks into crypto wallets their owners have locked…
- Joe KilianAmerican cryptographer whose 1992 succinct arguments are the grandparent of today's zk-SNARKs.
- Joe SullivanFormer chief security officer at Facebook and Uber, and the first security chief convicted over how he handled a breach.
- Jogeir LiljedahlNorwegian tracker musician whose early-nineties Amiga modules are among the most widely circulated the scene produced.
- Johan HåstadThe KTH professor who proved you can build pseudorandomness out of any one-way function at all — and who has won the Gödel…
- Johan HelsingiusThe Finn who ran the internet's most popular pseudonymous remailer until the Church of Scientology and a court showed…
- Johannes BuchmannGerman number theorist at TU Darmstadt who built one of Europe's first post-quantum research groups – well before anyone…
- Johannes TrithemiusGerman abbot (1462–1516) who wrote the first printed book on cryptography and coined the word steganography.
- Johannes UllrichThe physicist who started collecting other people's firewall logs in 2000 and ended up with one of the internet's first…
- John AbowdThe economist who, as chief scientist of the U.S. Census Bureau, pushed differential privacy into the 2020 American census.
- John AtanasoffThe physicist who reasoned out what an electronic computer had to look like, built one, lost interest, and was finally…
- John BackusLed the Fortran project and thereby proved a compiler could produce code good enough — which nobody believed in 1954.
- John BardeenThe only person to win two Nobel Prizes in Physics — one for the transistor, one for superconductivity.
- John CarmackMade 1990s PC hardware do things it was not built for — and then released the source code to the engines.
- John ChowningAmerican composer and Stanford researcher (born 1934) who discovered FM synthesis and thereby handed Yamaha the best-selling…
- John GilmoreEarly Sun employee who spent his money founding the EFF, the cypherpunks and a company that sold support for free software.
- John IoannidisNetwork researcher whose 1993 swIPe protocol was one of the direct ancestors of IPsec.
- John KelseyCryptographer from Schneier's Counterpane who helped design Twofish and Yarrow, then moved to NIST to scrutinise everyone…
- John LambertThe Microsoft veteran behind what may be the security industry's most quoted sentence about how defenders get it wrong.
- John MarkoffThe New York Times reporter who put hackers on the front page, and ended up part of the most contested hacker story of them…
- John MauchlyThe physicist whose memo about vacuum-tube calculators became ENIAC — and whose five days in Iowa in 1941 later cost him the…
- John McAfeeThe antivirus pioneer whose later life made the company bearing his name wish it were called something else.
- John McCarthyGave the field both its name and its first language — the term "artificial intelligence" and the Lisp programming language…
- John McLeanThe NRL researcher who showed that Bell–LaPadula's security proof could be satisfied by a system that wasn't secure at all.
- John NapierA landowner who invented the logarithm in his spare time, regarded his commentary on the Book of Revelation as his real…
- John Perry BarlowGrateful Dead lyricist and Wyoming cattle rancher who co-founded the EFF and wrote the internet's most quoted manifesto.
- John PollardThe British mathematician whose algorithms decide how big your keys have to be.
- John RushbyBritish computer scientist who proposed the separation kernel in 1981 – the idea that the safest way to share a computer is…
- John Scott-RailtonCitizen Lab researcher in Toronto who specialises in finding government spyware on the phones of journalists and activists.
- John TiltmanBritish army officer and cryptanalyst, one of the most experienced codebreakers at Bletchley Park.
- John ViegaAmerican security engineer who co-wrote the first book on building secure software, co-designed GCM — and wrote GNU Mailman…
- John von NeumannDescribed in 1945 the computer architecture that nearly every machine since has been built on — program and data in the same…
- John YoungNew York architect who in 1996 started Cryptome, an archive of documents governments would rather not see published.
- Johnny LongThe pen tester who showed that an ordinary search engine is one of the best reconnaissance tools around — provided you ask…
- JolietMicrosoft's 1995 extension to ISO 9660 that gave CDs long, Unicode-encoded filenames.
- JollaFinnish Nokia defectors who refused to let MeeGo die and built Sailfish OS from the wreckage.
- Jolt PhysicsA modern open 3D physics engine built for Horizon Forbidden West — multithreaded, deterministic and free since 2021.
- Jon CallasCryptographer and engineer who wrote much of the OpenPGP standard and then tried to make encrypted calls something ordinary…
- Jon EricksonAuthor of the book that taught a lot of people to read a stack frame before they ever read a security policy.
- Jon Lech JohansenThe Norwegian who helped crack DVD copy protection at 15, then got acquitted twice for it.
- Jon PostelEffectively ran the internet's address registry and standards documents single-handed for nearly thirty years.
- Jonathan JamesThe teenager "c0mrade" who broke into NASA and the Pentagon and became the first juvenile in the US jailed for computer…
- Jonathan KatzAmerican cryptographer best known as co-author of Katz–Lindell, the textbook that taught a generation to define security…
- Jonathan LittmanAmerican journalist behind the two most argued-over hacker books of the 1990s, starring Mitnick and Poulsen.
- Jonathan ZdziarskiThe researcher who knew more about what an iPhone records about its owner than most people at Apple.
- Joseph BonneauAmerican researcher who measured just how weak passwords really are, then showed why none of their replacements has won…
- Joseph DeschThe engineer who led the build of the US Navy's Bombe — and carried the secrecy to his grave, tormented by what he was never…
- Joseph MauborgneUS Army signals officer who made Vernam's cipher unbreakable by removing the reuse of its key.
- Joseph MennSecurity reporter who revealed that the NSA paid RSA $10 million for a backdoored default.
- Joseph PoppAmerican biologist who in 1989 mailed tens of thousands of floppies carrying the AIDS Trojan, earning him credit for the…
- Joseph SilvermanBrown University number theorist who wrote the standard text on elliptic curves, then helped invent a cryptosystem that…
- Josh AasCo-founder and head of ISRG, the outfit that made free TLS certificates the default rather than the exception.
- Josh BenalohThe cryptographer who has spent four decades on a single question: how do you prove a vote was counted correctly without…
- Josh CormanThe security figure who shifted the debate from data breaches to vulnerabilities that can hurt people: pacemakers, cars and…
- Joshua JaffeCo-discoverer of differential power analysis — the name that usually gets dropped when people say "Kocher's attack".
- Joshua WrightAmerican security researcher who showed that wireless networks usually fall to the password, not the cipher.
- Jotai"Jotai" (状態, Japanese for "state") — atomic state management. const countAtom = atom(0) + useAtom(countAtom). Like Recoil…
- JournallingWriting down what you intend to do before doing it, so the filesystem can be repaired after a power cut.
- Joxean KoretSpanish security researcher who showed that antivirus software, with its privileges and its file parsers, is often the most…
- JoybubblesBlind phone phreak who controlled the American telephone network by whistling 2600 Hz – no whistle required.
- JoyentThe San Francisco cloud company that stewarded Node.js and ran containers on Solaris descendants before it was cool.
- JPA (Jakarta Persistence API)Java's standard for object-relational mapping, originally JSR 220 (2006), today Jakarta Persistence. A specification — not…
- JPEGDominant lossy image compression. ISO standard 1992. Discrete Cosine Transform-based. 30+ years old, still nearly default…
- jqA command-line tool for filtering and reshaping JSON. Written by Stephen Dolan in 2012. Best described as sed for JSON — and…
- jQueryThe library that made JavaScript bearable when browsers agreed on nothing — and whose ideas then became the standard.
- jQuery MobileThe framework meant to turn web pages into mobile apps using data attributes — retired in 2021.
- jQuery UIThe official widget layer on top of jQuery — and in practice the date picker half the web used for a decade.
- JS1kA yearly contest to write something impressive in no more than 1,024 bytes of JavaScript — the demoscene's size classes…
- jsDelivrFree, open-source CDN that serves npm and GitHub packages to half the web.
- JSFXREAPER's format for audio effects written as plain text files in the EEL2 language and compiled on load.
- JSON (JavaScript Object Notation)A text format for exchanging structured data between systems — easy for both humans and computers to read.
- JSON modeLLM feature that guarantees the output is valid JSON. OpenAI launched it in 2023; Anthropic + Google followed. Implemented…
- JSON SchemaStandard for describing JSON structures — types, required, patterns, validation.
- JSON-LDJSON with a @context that gives its keys global meaning — RDF for people who would rather not look at XML.
- JSON-RPCSimple RPC protocol over JSON. v1 (2005), v2.0 (2010, most used). Request…
- JSON5JSON superset for humans. Adds: comments, trailing commas, single quotes, unquoted keys, multi-line strings, hex numbers…
- JSONBPostgres's binary-stored JSON type — indexable, fast to query, schemaless flexibility inside a relational database.
- JSONB (Postgres)PostgreSQL type for JSON stored in binary form. Faster than the JSON text type (parsed once, stored structured). Supports…
- JsonnetA data templating language extending JSON with variables, functions and inheritance. Built for the problem of ten thousand…
- JSXJavaScript syntax extension that looks like HTML — const el = <div className="x">Hi</div>. Babel/SWC/TypeScript transforms…
- JTAGJoint Test Action Group (IEEE 1149.1) — a standard interface for testing, debugging, and programming chips at the board…
- JUCEThe C++ framework underneath a large share of all audio plugins and quite a few DAWs.
- Jude MilhonHacker and writer "St. Jude", who coined the word cypherpunk in 1992.
- JugheadLocal search for Gopher: it indexed the menu tree of a single server or a handful, rather than the whole network.
- Juice jackingA compromised public USB charging station — charges your phone while simultaneously trying to exfiltrate data or install…
- JuliaScientific language launched 2012 — looks like Python, runs like C. Multiple dispatch, JIT via LLVM, type-stable functions…
- Julian AssangeAustralian former hacker who founded WikiLeaks in 2006 and spent most of the next eighteen years either in court or confined.
- Juliano RizzoArgentine security researcher who, with Thai Duong, turned old cryptographic warnings into working attacks on TLS and web…
- Jumbo frameEthernet frame larger than the standard 1500 bytes. Typically 9000 bytes ("9K"). Reduces CPU overhead per byte (fewer frames…
- Jumbo framesEthernet frames larger than the standard 1500-byte MTU — typically 9000 bytes. Reduces CPU overhead per byte of data…
- Jumbo-frame MTUEthernet frames larger than the standard's 1500 bytes, typically 9000 bytes ("jumbo frames"). By sending more data per frame…
- Jump bufferingRemembering a jump press for a few frames so a jump the player pressed just before landing still fires on touchdown.
- Jump flooding algorithm (JFA)A GPU algorithm that computes approximate Voronoi diagrams and distance fields in a logarithmic number of passes.
- Jump point searchAn optimization of A* on uniform grids that jumps straight over uninteresting cells and only stops at the points where a…
- JUNETJapan's first academic computer network, started in 1984 as a UUCP link between three Tokyo universities.
- Jung Hee CheonSouth Korean cryptographer, the first C in CKKS: the homomorphic scheme that accepts approximate answers and became useful…
- Juniper NetworksThe one router maker that ever seriously challenged Cisco in the internet backbone.
- JUnitJava's testing framework, and the archetype the entire xUnit family copied.
- JupyterNotebook environment where code, results, charts and prose live in the same document. Split out of IPython in 2014, which…
- Juraj SomorovskySlovak researcher who specialises in showing that old cryptographic mistakes still work — in SAML, in cloud APIs and in TLS.
- Justin SchuhCo-author of the code auditor's doorstop, and for a decade one of the people responsible for keeping Chrome hard to break.
- JVM (Java Virtual Machine)Runtime that executes Java bytecode. Stack-based VM with JIT compilation, garbage collection, class loading. Powers Java…
- JWMJoe's Window Manager: a small window manager in plain Xlib with a built-in taskbar, pager and clock, configured in XML and…
- JWT (JSON Web Token)A signed text string that proves who you are — common for API authentication and single sign-on.
- JWT claimsThe key-value pairs in a JWT's payload. RFC 7519 registers standardised short names (3 letters).
- JWT revocationHow to "log out" a JWT token before its expiry. Hard technical problem: JWTs are stateless by design — the server can't…
K
- .kkriegerA complete first-person shooter in 96 kilobytes — every asset is computed at launch rather than stored.
- Apache KafkaDistributed message log for billions of events — the foundation of many real-time systems.
- AWS KinesisAWS family for stream data: Data Streams (Kafka competitor), Data Firehose (managed delivery to S3/Redshift/OpenSearch)…
- k-DOPA bounding volume shaped by k half-spaces with fixed normal directions — tighter than an AABB, cheaper to test than the real…
- K-lineAn IRC server's way of locking a user out entirely — and a verb for whoever it happened to.
- K-SystemBob Katz's metering scheme that ties the meter's zero point to a calibrated monitoring level, turning headroom into a…
- K-weightingThe frequency filter audio passes through before LUFS is measured: a rough model of how the head and ear colour what we hear.
- k0sA Kubernetes distribution that is one single binary with no dependencies on the host system. Download the file, run it, done.
- K12NetA FidoNet-based network for schools from around 1990, where teachers and pupils held discussions long before classrooms had…
- k3sLightweight CNCF-certified Kubernetes — the entire control plane in a single 70 MB binary, with SQLite (or etcd) as the…
- k8sShorthand for Kubernetes. "K" + 8 letters + "s".
- K9sTerminal UI for Kubernetes. Go. Fernand Serrano, 2019. Vim-like keybindings — power users navigate between pods, services…
- KA9Q NOSAn entire TCP/IP stack, servers and clients included, packed into one DOS program by a radio amateur who wanted internet…
- Kafka StreamsJVM library for stream processing on top of Apache Kafka. Topology DSL for transformations, aggregations, joins between…
- Kaisa NybergFinnish cryptographer whose S-box construction ships inside every AES implementation on the planet.
- KakaoTalk (카카오톡)South Korea's default app — 95 % of smartphone users have it. Like WeChat but for Korea.
- KaleidoscopeShareware for classic Mac OS that reskinned the entire interface, giving the Mac the themes Apple itself never shipped.
- Kalin–Burkhart machineA 1947 electrical logic machine that tested the truth values of Boolean expressions — built by two logic students at Harvard.
- KanbanVisual workflow with columns (Todo, Doing, Done) and cards moving between them.
- KanikoGoogle tool to build Docker images within Kubernetes without Docker daemon. Critical for CI/CD within containers…
- Kansas City standardA 1975 attempt to store computer programs as audio on ordinary cassette tape using one vendor-neutral encoding.
- KaomojiJapanese text faces read the right way up, where the eyes carry the emotion instead of the mouth.
- KargoHandles promotion of changes between environments in a GitOps setup — which is precisely the step Argo CD deliberately takes…
- Karl KochWest German hacker from Hanover, known as "Hagbard Celine", who belonged to the ring that sold break-ins to Western…
- Karma (Reddit)Numeric score on a Reddit account: net (upvotes − downvotes) on all comments + posts. Shown on profile. No direct function…
- KarmadaRuns many Kubernetes clusters as though they were one. You submit a perfectly ordinary resource plus a rule for which…
- KarpenterNode autoscaler for Kubernetes that provisions EC2 instances directly instead of going through ASGs — faster and better…
- Karplus–StrongA synthesis algorithm that sounds like a plucked string by circulating a short burst of noise through a delay line with a…
- Karsten NohlGerman researcher who spent more than a decade showing that the infrastructure in our pockets runs on cryptography nobody…
- Karsten ObarskiThe German who wrote Ultimate Soundtracker and, without quite meaning to, invented tracker music.
- Karthikeyan BhargavanResearcher who proves cryptographic protocols correct and, along the way, finds the places where they aren't.
- Kaseya VSA attackJuly 2021 ransomware attack — REvil exploited zero-day in Kaseya VSA (RMM platform) to encrypt ~1500 companies via 60 MSPs.
- Kasiski examinationThe technique that recovers a Vigenère key's length — and with it, ended the cipher's reputation as unbreakable.
- Kaspersky LabThe Moscow firm whose researchers exposed some of the most sophisticated state spyware ever found — and which was eventually…
- KASUMIThe block cipher that protected 3G mobile traffic, derived from MISTY1 and later attacked with related keys.
- Kata ContainersOCI-compatible runtime that runs each container in its own lightweight VM — real kernel isolation with container ergonomics.
- Kathleen BoothWrote what is generally reckoned the first assembly language in 1947, for a relay machine in the basement of a London…
- Katie HafnerAmerican journalist who wrote two of the early standard texts on networked history: one about the hackers, one about the…
- Katie MoussourisThe hacker who got Microsoft and the Pentagon to pay strangers to find their security holes.
- Katie NickelsThe threat intelligence analyst who led MITRE ATT&CK as it went from an internal spreadsheet to the industry's shared…
- Kaveh RazaviHardware security researcher with a habit of demonstrating that Rowhammer defences don't defend.
- Kay McNultyIrish-born mathematician, one of ENIAC's six original programmers, later married to one of the machine's two designers.
- KAYAKTravel meta search engine — searches across Expedia, Booking, airlines and shows the best price. Bought by Priceline (now…
- KayproA test-equipment firm that built a better Osborne in a metal box and threw in an office suite for free.
- kbin / mbinFediverse software that combines Reddit-style (link aggregator + threaded comments) with Mastodon-style (microblog)…
- kd-treeA binary tree that partitions k-dimensional space by cycling the splitting axis at each level.
- KDEA Linux desktop environment built on Qt, known for making essentially everything configurable.
- KDE PlasmaKDE's desktop since KDE 4 (2008): panel, desktop and every small program built from the same interchangeable widgets, the…
- kdesktopThe process that was the desktop itself in KDE 2 and 3 — wallpaper, icons, right-click menu, screensaver and Alt+F2 — until…
- KDMKDE's display manager from KDE 1.0 to Plasma 5, built on XDM's code and replaced by SDDM.
- KDriveKeith Packard's stripped-down X server from the turn of the millennium, built for handhelds with a megabyte to spare, which…
- KEDA (Kubernetes Event-Driven Autoscaling)An add-on that lets Kubernetes scale on how much work is waiting rather than on processor load. And down to zero pods when…
- Keep-aliveKeep a TCP connection open for multiple requests instead of closing and reopening every time.
- Keeper SecurityThe Chicago company behind the Keeper password manager, best known outside its customer base for suing a journalist who…
- Kees CookThe Linux developer who has spent a decade teaching the kernel to defend itself, one merge at a time.
- KefrensA Danish Amiga group that made demo history twice: once with Desert Dream and once with an effect named after it.
- Kefrens barsWaving bars where each screen line draws exactly one bar — an effect named after the Amiga group that made it famous.
- Keith AlexanderThe NSA director who wanted to "collect it all" and had to answer for it when Snowden showed they nearly had.
- Keith PackardThe man behind nearly everything that made X11 modern — Render, Composite, RandR, Xft and fontconfig — and whose expulsion…
- KEMETCapacitor maker with roots in Union Carbide, best known for tantalum capacitors.
- Kemper ProfilerA guitar processor that measures a real amplifier with test signals and plays back an imprint of it, rather than simulating…
- Ken BibaMITRE computer scientist who in 1977 formulated the Biba model — the formal security model for integrity rather than secrecy.
- Ken ThompsonWrote the first Unix on a cast-off PDP-7 in a month in 1969 — and showed fifteen years later why you cannot trust any…
- Kendall Square ResearchA Massachusetts supercomputer company whose machines had nothing but cache, and whose accounting turned out to be more…
- Kenn WhiteSecurity researcher who launched a crowdfunded audit of TrueCrypt in 2013 — and watched its developers walk away halfway…
- Kenny PatersonCryptographer who specialises in showing that protocols secure on paper are not secure as actually implemented.
- KerberoastingAn Active Directory attack where an attacker requests Kerberos service tickets for accounts with an SPN (Service Principal…
- KerberosClassic authentication protocol from MIT — a ticket system for secure login without sending passwords over the network.
- Kerckhoffs's principleA cryptosystem must stay secure even when everything except the key is known to the enemy.
- Keren ElazariIsraeli security analyst who sold the idea of hackers as the internet's immune system to an audience that mostly knew them…
- KermitA file-transfer protocol from Columbia University, built to work everywhere rather than fast — and named after the frog…
- KERNALThe Commodore 64's operating system in ROM — and a misspelling that became a standard.
- KernelThe heart of an operating system — runs in privileged mode (ring 0), manages CPU scheduling, memory, drivers, file systems…
- Kernel Mode Setting (KMS)Moving display mode configuration — resolution, refresh rate, which outputs are lit — from the X server's drivers into the…
- Kernel moduleCode loaded into the running kernel without a reboot — nearly always a driver or a filesystem.
- Kernel spaceThe portion of memory and privilege only the kernel can reach — where all hardware access happens.
- Kernel Streaming (WDM-KS)A way to send audio straight to the Windows kernel driver, bypassing the system mixer.
- Kerrison PredictorA 1939 British anti-aircraft computer where the operator's only job was to keep the sight on the aircraft; the machine did…
- KestrelThreat-hunting language. IBM 2021. Composable + reusable hunting flows over multiple data sources (EDR, SIEM, packet…
- KEV CatalogKnown Exploited Vulnerabilities — CISA catalog of CVEs actually exploited in the wild. Launched 2021. US federal agencies…
- Kevin BeaumontThe British defender who names the vulnerabilities the rest of the industry then talks about.
- Kevin FinisterreAmerican vulnerability researcher best known for walking away from a $30,000 bug bounty in 2017 rather than sign DJI's…
- Kevin FuThe researcher who showed in 2008 that an implanted defibrillator could be controlled over the air, laying the groundwork…
- Kevin MandiaFounder of Mandiant, the firm that made incident response a brand and named a Chinese military unit in public.
- Kevin MitnickThe most wanted computer intruder of the 1990s, whose point throughout was that people are easier to break than systems.
- Kevin PoulsenThe hacker who won a Porsche by hijacking a radio station's phone lines, then became one of the security world's best…
- KewlersA Finnish PC demogroup best known for winning Assembly with a demo about a year most of the audience had forgotten.
- Key agreementA protocol in which two parties jointly derive a shared secret without ever sending it across the channel.
- Key attestationA signed statement from the hardware that a particular key was generated inside it and cannot be exported.
- Key ceremonyA formal, documented procedure for generating keys so that no single person can control them.
- Key check value (KCV)A short fingerprint of a key that lets two parties compare keys without revealing them.
- Key commitmentThe property that a ciphertext can only be opened by one key, which many modern AEAD ciphers do not guarantee.
- Key derivation functionTurns something secret into a key of the right length and shape — but which KDF to pick depends entirely on how good the…
- Key detectionLetting an algorithm work out which key a recording is in, mostly so DJs can mix tracks that sit well together.
- Key diskCopy protection that requires a specific, deliberately uncopyable original disk to be in the drive when the program starts.
- Key diversificationGiving every card or device its own key, derived from a master key and the device's identity, so one broken device doesn't…
- Key encryption keyA key whose only job is to encrypt other keys, so that only this one needs protecting in hardware.
- Key escrowA third party holds a copy of the key, so authorities can read along when entitled to — and everyone else when they manage…
- Key hierarchyThe arrangement in which a root key protects key-encryption keys, which in turn protect the keys that encrypt the data.
- Key injectionLoading cryptographic keys into a device, usually during manufacturing, in a controlled way.
- Key ladderA chain of key derivations in which each level unlocks the next, and only the top key needs to sit in secure hardware.
- Key management serviceA cloud service that creates, stores and uses encryption keys, so the customer does not have to run their own key hardware.
- Key recovery attackKey recovery means getting hold of the key, whether through cipher weaknesses, a side channel or a protocol mistake.
- Key rotationRegularly replacing encryption keys — so a leaked key only exposes limited data.
- Key scheduleThe procedure that stretches a master key into the subkeys a cipher uses in each round.
- Key separationThe principle that every key serves exactly one purpose, with keys for different purposes derived separately.
- Key sheetThe daily sheet of Enigma settings that made the machine usable for its own army, and for anyone who intercepted its traffic.
- Key spaceThe set of all possible keys, and the number that decides whether brute force is a theory or a practical plan.
- Key stretchingMaking every password guess expensive by running a function thousands or millions of times.
- Key trackingLetting the note's pitch steer another parameter, usually the filter cutoff, so high notes don't sound duller than low ones.
- Key whiteningXOR-ing extra keys before and after a block cipher to make brute force harder without changing the cipher itself.
- KeybaseE2EE chat + crypto file-sharing + identity proofs. Founded 2014 by Chris Coyne and Max Krohn. Acquired by Zoom in 2020…
- KeyboardPrimary text input device. QWERTY layout (1873, designed to slow typesetters on typewriters). Cherry MX switches define…
- Keyboard traversal (Motif)Motif's model for reaching every button and field without a mouse: widgets are grouped into tab groups, Tab jumps between…
- KeyCDNA Swiss low-cost CDN that courted developers while the big players billed up front.
- KeycloakOpen-source IdP — OIDC, SAML, OAuth 2.0, LDAP/AD bridge, MFA, social login, user federation. The default choice for…
- Keyed alphabetA substitution alphabet in which a keyword decides the order of the letters.
- KeyframeA frame complete in itself — everything between merely describes the difference from something else.
- KeygenThe program that computes valid licence keys — often with a little chiptune curling away in the background.
- KeyloggerMalicious code (or hardware) that records every keystroke — captures passwords, credit cards, everything.
- KeymapNotifyAn X11 event that reports which keys are already held down when a window gains focus or the pointer enters it.
- KeyPress and KeyReleaseThe X11 events for a key going down and coming up, which deliver a key number and leave the client to work out what it meant.
- KeypunchThe keyboard where a computer's input was literally knocked out of the card stock, one character at a time, by someone paid…
- KeysightThe part of Hewlett-Packard that still does what HP started out doing: measuring things.
- KeystreamThe pseudorandom bit sequence XORed with the plaintext in a stream cipher.
- KeyswitchA key outside an instrument's playing range that makes no sound but switches articulation — legato, staccato, pizzicato — in…
- KeysymX11's name for what a key means, as opposed to the keycode, which only says which key was pressed.
- Keyword cipherA substitution cipher in which a keyword decides how the alphabet is shuffled.
- kfmKDE 1's file manager, which was also its web browser, FTP client and desktop icon layer — and whose HTML widget is the…
- Khufu and KhafreRalph Merkle's pair of block ciphers from Xerox, named after pharaohs and published despite the NSA asking nicely that they…
- KiboThe Usenet user who searched the whole network for his own name and replied to everyone who mentioned it — and thereby…
- KickTwitch competitor launched 2022. 95%/5% revenue split for streamers (vs Twitch 50/50 default, 70/30 for partners). Backed by…
- Kick AssemblerA 6502 assembler with a built-in scripting language that computes data, tables and graphics at assembly time — the current…
- KickerThe panel of KDE 2 and 3, K menu at the far left, that gave the Linux desktop its Windows 95 silhouette for eight years.
- KickstartThe Amiga's boot ROM — it wakes the hardware and loads the core of AmigaOS before a floppy has even spun up.
- Kill chainA model (Lockheed Martin's "Cyber Kill Chain") describing the sequential steps in a targeted cyberattack — from…
- Kill planeAn invisible height limit beneath the level: anything that falls below it is destroyed, and players who do are killed or…
- KillfileThe Usenet reader's file of patterns for things you don't want to see. The block button's grandfather, invented before…
- Kim CameronMicrosoft's identity architect who in 2005 wrote down seven laws of digital identity — having watched Passport break most of…
- Kim ZetterSecurity journalist who wrote the standard account of Stuxnet.
- Kimball tagThe little punched-card tags on retail garments read by machine at the till — the barcode's predecessor in the shop.
- kindKubernetes IN Docker — runs Kubernetes cluster where nodes are Docker containers instead of VMs. Designed for testing +…
- Kinematic bodyA physics body moved by code rather than by forces — it pushes dynamic objects but is never pushed back itself.
- KingThe Stockholm company behind Candy Crush Saga, which began with cash-prize web games and ended up with half the world's…
- KingsoftThe Chinese software house behind WPS Office, and the place where Xiaomi's founder learned how to run a company.
- Kingston TechnologyThe world's largest independent maker of memory modules, started in 1987 around a single SIMM and still owned by its two…
- kinput2The default Japanese input server on X11 for fifteen years: the program that took romaji from the keyboard, asked a…
- KinstaPremium host that runs managed WordPress and nothing else, entirely on Google Cloud.
- KioxiaToshiba's former memory division — the very operation where NAND flash was invented, sold off to rescue its parent.
- Kirk WiebeNSA analyst who walked out alongside William Binney in 2001 in protest at how the agency's surveillance was being expanded.
- KISS (Keep It Simple, Stupid)Design principle: the simplest solution that solves the problem is usually the best. Coined by aircraft engineer Kelly…
- KittyA GPU-rendered terminal emulator by Kovid Goyal (2017), the same developer behind the Calibre ebook program. It draws text…
- kkaptureA tool that records Windows demos as flawless video by lying to them about the time.
- kkrunchyFarbrausch's executable packer for 64k intros, built to squeeze x86 code harder than general-purpose packers could.
- KL-7The NSA's 1950s rotor machine, standard for US and NATO traffic for three decades of the Cold War.
- KLAA company that makes no chips at all, but tells everyone else what went wrong with theirs.
- Klára Dán von NeumannHungarian-born coder who wrote and debugged ENIAC's 1948 Monte Carlo runs, with no formal training in mathematics.
- KlarnaThe Stockholm company that turned the invoice into an online payment method: the buyer gets the goods first, Klarna takes…
- Kludge lineHidden metadata lines in FidoNet messages, each starting with a Ctrl-A character that mail readers normally kept out of…
- KlystrackA chiptune tracker that synthesises its sounds instead of sampling them, written by the Finnish developer kometbomb.
- KMIPA standard protocol for asking a key server to create, hand out, rotate and revoke encryption keys.
- KnativeServerless layer on top of Kubernetes — scale-to-zero, request-based autoscaling, blue-green deploys, all declared as CRDs.
- Knee (compressor)The shape of a compressor's transfer curve around the threshold — a sharp corner or a gentle bend.
- Knex.jsSQL query builder, NOT an ORM — builds up queries as a chainable API without mapping rows to classes. Includes a migration…
- KNIMEGerman node-based data-science platform where the entire workflow is a graph — free and open source since 2006.
- KnockbackThe shove that throws a character backward when hit — in some games the actual win condition rather than a side effect.
- Knockout.jsEarly MVVM framework for JavaScript — observable-based reactivity, declarative data binding via HTML attributes. Steve…
- Know your customer (KYC)The obligation for banks and payment companies to know who the customer is, where the money comes from and what it is for.
- KnowBe4The company behind the fake "IT department" phishing email you clicked last quarter.
- Knowbot Information ServiceA meta-search across the internet's fragmented people directories, run by the organisation Robert Kahn founded.
- Knowledge cutoffThe date at which a model's training data ends. Anything that happened afterwards does not exist for the model — it cannot…
- Knowledge distillationTrain a small "student" model to mimic a large "teacher" — copies not just its output but its probability distribution over…
- Knowledge graphA structured representation of entities and their relationships — nodes + edges with meaning.
- Known good die (KGD)An unpackaged piece of silicon that has been fully tested and guaranteed to work. A concept that barely mattered until…
- Known-answer test (KAT)A self-test in which a cryptographic module encrypts, hashes or signs fixed inputs and checks the result against a…
- Known-IV attackIf the attacker knows the IV in advance and can choose plaintext, they can test guesses one block at a time. That is the…
- Known-key attackA test in which the attacker knows the key and can still tell the cipher's output apart from random data.
- Known-plaintext attackThe attacker holds both plaintext and ciphertext for some messages and uses them to work out the key.
- KNXEuropean standard for building automation — lighting, blinds, heating, AC. Replaced EIB, BatiBUS, EHS in 1999.
- Ko-fi"Buy me a coffee" — one-off donations to creators for $3 (the price of a coffee). British, indie, no platform fee on the…
- KoalaPainterThe C64 paint program whose save format, KOALA, became the scene's de facto standard for multicolor pictures.
- Kobbi NissimIsraeli computer scientist who first proved that "anonymised" statistics leak, then helped write the cure.
- KodakThe film giant that invented the digital camera and then went bankrupt because of it.
- KOM (conferencing system)The Swedish computer conferencing system from 1978, where users posted in "meetings" — Sweden's answer to newsgroups, a few…
- KonamiA Japanese game company that started with jukeboxes, gave the world the Konami Code and Metal Gear, and now earns much of…
- KongAPI gateway built on Nginx + OpenResty — Mashape, 2015 (now Kong Inc.). Supports rate limiting, auth and transformations via…
- KonquerorKDE 2's file manager and web browser in one window, assembled from swappable components, whose HTML engine KHTML became the…
- Konrad ZuseBuilt the world's first programmable automatic computer in his parents' living room in Berlin, and only learned of everyone…
- KontaktNative Instruments' software sampler, which turned into the platform for an entire industry of instrument libraries.
- Kook (Usenet)Usenet's word for the poster with exactly one theory and unlimited time to explain it.
- Korg M1Korg's 1988 sample-based synth that popularised the workstation: sounds, effects and sequencer in a single box.
- Korg MS-20Korg's 1978 semi-modular monosynth, with a patch panel down the right-hand side and a filter that screams once you turn up…
- Kostya KortchinskyFrench exploit developer who showed in 2009 that a virtual machine could climb out of its VMware cage.
- KotlinJetBrains' more modern alternative to Java on the JVM (2011, v1.0 2016). Google adopted it as the primary language for…
- KPartsKDE's component framework since KDE 2, letting one application borrow another's view — a PDF viewer, a terminal, a text…
- KrakenOne of the oldest crypto exchanges, built by people who would rather talk about security than about regulators.
- KremvaxThe 1984 April Fools' post announcing that the Soviet Union had joined Usenet, sent from a machine called kremvax in the…
- Kris KasperskyPen name of Russian author Nikolay Likhachev, whose books on disassembly and reverse engineering taught a generation to read…
- Kristin LauterMathematician who moved homomorphic encryption and isogeny-based cryptography from the blackboard into code.
- Kristin PagetHardware hacker who intercepted the audience's phone calls at DEF CON 2010 with a home-built base station.
- KryhaThe most confidently marketed cipher machine of the interwar years, which turned out to be breakable in an afternoon.
- KryoFluxA USB board that reads a floppy's raw magnetic flux to preserve even copy-protected disks.
- KryptosA copper sculpture outside CIA headquarters carrying four encrypted passages, the last of which has held out since 1990.
- ksqlDBSQL-database-like layer on top of Kafka — write streaming queries in SQL, get materialised views and push/pull queries. From…
- KuaishouChina's second-largest short-video platform and ByteDance/Douyin's stubborn challenger, known internationally as Kwai.
- kube-benchRuns the CIS Kubernetes Benchmark against an existing cluster and reports which controls pass, which fail, and what to do…
- kube-proxyPer-node component that implements the Kubernetes Service abstraction. Handles virtual ClusterIP — packets to ClusterIP are…
- kube-vipGives the Kubernetes control plane a floating virtual IP on bare metal, so kubectl has an address to talk to even while the…
- kubeadmOfficial Kubernetes tool to bootstrap clusters. kubeadm init on master, kubeadm join on workers. Sets up control plane…
- KubecostWorks out what each namespace, service and team actually costs in a shared cluster. The cloud bill only shows what the nodes…
- kubectlThe command-line tool for Kubernetes — pronounced "kube-control" or "kube-cuddle".
- kubectxCLI tool for quickly switching kubeconfig context and namespace. Ahmet Alp Balkan, 2017. Combines with fzf for an…
- kubeletPer-node agent in Kubernetes. Communicates with apiserver, schedules containers via CRI (containerd, CRI-O), reports node +…
- Kubernetes (K8s)A system that coordinates lots of containers across many servers — starts, scales, heals, balances.
- KubeVirtRuns virtual machines as ordinary Kubernetes resources, in pods, alongside the containers. Became suddenly very interesting…
- KueueKubernetes batch job queue system. CNCF project under sig-scheduling, GA in 2024. Addresses that the Kubernetes default…
- KumaService mesh from the Kong folks — Envoy-based data plane, built for multi-zone deployments.
- Kung Fu FlashAn open-source C64 cartridge with an SD slot that can impersonate almost any other cartridge.
- Kuro5hinDiscussion site from 1999 where the readers themselves voted on which articles got published. An early and instructive…
- Kurt GödelProved mathematics cannot settle everything about itself, using an encoding trick that is the whole idea behind treating…
- Kurzweil Reading MachineThe first machine that read ordinary printed text aloud — omni-font OCR, a flatbed scanner and a speech synthesizer in a…
- KustomizeKubernetes configuration manager that works via overlays — base + patches instead of templating. Built into kubectl since…
- KuznyechikThe Russian standard's 128-bit block cipher, which replaced GOST 28147-89 for new systems.
- KV cacheThe cache that stores the attention mechanism's "key" and "value" vectors for already-processed tokens, so they don't have…
- KVM (Kernel-based Virtual Machine)Linux kernel module that turns the kernel into a Type-1 hypervisor. Combined with QEMU for full hypervisor functionality…
- KWinKDE's window manager since 2000, which over the years became a compositor, an effects engine and a Wayland server.
- kwmKDE 1's window manager, which gave Linux a Windows 95 look and left behind the window hints that became EWMH.
- KWOK (Kubernetes WithOut Kubelet)Simulates thousands of nodes that don't exist, so you can test how a cluster behaves at a scale you could never afford to…
- KyndrylIBM's old outsourcing business, spun off in 2021 because IBM wanted to be a cloud company rather than run other people's…
- KyoceraJapanese conglomerate that started with ceramic chip packages and ended up with printers, phones and a founder who rescued…
- KyvernoKubernetes policy engine where rules are written as regular K8s resources in YAML — no new DSL to learn.
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- AWS LambdaThe FaaS pioneer — upload a function, AWS runs it on events (HTTP, S3, queue, schedule). Billed per millisecond of execution.
- Grafana Loki"Prometheus for logs" — a cheaper log system that only indexes metadata, not the text itself.
- L0pht Heavy IndustriesThe Boston hacker collective that told the US Senate in 1998 it could take down the internet in thirty minutes.
- L1/L2/L3 cacheThe three common cache levels in a modern CPU, from fastest/smallest (L1) to largest/slowest (L3). L1 and L2 are private per…
- L2TP (Layer 2 Tunneling Protocol)A tunnelling protocol from 1999 that carries link-layer frames over an IP network. It merges Cisco's L2F with Microsoft's…
- L4S (Low Latency, Low Loss, Scalable throughput)An architecture for getting internet queuing delay down to a millisecond or so, by marking traffic that understands a new…
- Label printerA printer built for self-adhesive labels on a roll — usually direct thermal or thermal transfer, most often carrying a…
- Labeler (Bluesky)A moderation service in Bluesky that puts labels on posts or accounts — e.g. "spam", "NSFW", "misinformation". Users…
- labwcOpenbox for Wayland — a stacking compositor that reads Openbox's config files, draws title bars on the server side, and in…
- Lace cardA punch card with every hole punched — so little card stock left that it buckles in the reader and tears itself apart.
- LaceworkThe cloud security company valued at $8.3 billion in 2021 and sold for a fraction of that three years later — a…
- LACP (Link Aggregation Control Protocol)Combine several physical links into one logical "port channel" — increased bandwidth + automatic failover if a link dies.
- LACP fallbackA feature that lets an LACP port function as a regular single link if no LACP partner responds. It solves the problem that a…
- Ladar LevisonFounder of the email service Lavabit, who shut the whole thing down rather than hand over the key protecting every user.
- LADSPALinux's first shared audio plugin format, deliberately so simple it could barely do anything.
- Lag compensationThe server rewinds the world to the instant the shooter actually saw, so hits register despite network latency.
- Lai–Massey schemeThe third way to build a block cipher, alongside Feistel and SP networks: the round function is fed the difference between…
- LakehouseA data lake with database properties bolted on: cheap object storage underneath, ACID transactions and schema on top.
- Lam ResearchThe toolmaker that carves away what lithography has drawn — plasma etch is its home turf.
- LambdaAnonymous, short-lived function: x => x * 2. Also the name of AWS's serverless service.
- Lambda calculusFormal model of computation. Alonzo Church, 1930s. Three basic rules: variables, abstraction (λx.body), application (f x)…
- LambdaMOOA text world at Xerox PARC where players didn't just build the rooms but programmed them — and then had to invent their own…
- Lambros CallimahosA concert flautist who became the NSA's most influential teacher of cryptanalysis.
- LamerThe scene's universal insult for the incompetent — or for whoever steals someone else's work and puts their own name on it.
- Lamport clockA logical clock without synchronised time — counts events to produce a "happened-before" ordering in distributed systems.
- LAN partyCarrying a desktop tower, a 21-inch CRT and a power strip into a sports hall in order to escape your modem's latency.
- Lance CottrellCypherpunk who wrote Mixmaster and made anonymous email hold up against an adversary watching the network.
- Lance SpitznerFormer tank officer who turned honeypots from a curiosity into a research method.
- Land-and-groove recordingWriting data on both the grooves and the raised lands between them, nearly doubling track density on recordable optical…
- Landing zoneA data-free band at the inner edge of the platter where the heads settle at power-down so they never rest on data.
- LangChainThe earliest and most popular LLM orchestration framework — components (prompts, chains, agents, memory, tools) for building…
- LangfuseOpen-source LLM observability — track prompts, completions, cost, latency, tokens. Self-host or managed cloud.
- LangGraphState-machine framework for LLM agents — define nodes (steps) and edges (transitions) and run them as a graph with explicit…
- Language lawyerThe person who can tell you what the standard actually says, as distinct from what the compiler happens to do.
- LAPS (Local Administrator Password Solution)Microsoft's answer to every machine in the organisation sharing one local administrator password. Each gets its own random…
- LaravelDominant PHP framework. Taylor Otwell, 2011. MVC, expressive syntax, Eloquent ORM, Blade templates, Artisan CLI. The PHP…
- Largest Contentful Paint (LCP)A Core Web Vital that measures how long it takes before the page's largest visible content element (often a hero image or…
- Larian StudiosThe Belgian RPG studio that scraped by for nearly thirty years before Baldur's Gate 3 made it a household name.
- Larry EllisonRead Edgar Codd's paper on the relational model, realised IBM would not move quickly, and built the company that did instead.
- Larry PageThe doctoral project meant to map the web's link structure became the world's search engine instead.
- Lars KnudsenDanish cryptographer who stocked much of the 1990s toolbox for block cipher analysis and co-designed Serpent and Grøstl.
- larswmA tiling window manager from 1999, built on 9wm, that put the active window large on the left and stacked the rest in a…
- Laser printerPrinter that draws the page with a laser beam on a charged drum and fuses the toner powder with heat.
- LaserDiscThe first optical disc on the market: the size of an LP, carrying analogue video, and unable to record.
- LaserWriterApple's 1985 laser printer that, paired with the Macintosh and PageMaker, launched the desktop-publishing era.
- Last callers listThe BBS screen showing who had dialled in before you — guestbook, status board and surveillance log in one.
- LastPassCloud password manager that dominated its category until the vaults leaked.
- Latanya SweeneyComputer scientist who proved that "anonymised" data rarely is — by pulling a governor's medical record out of a voter roll.
- Late chunkingA RAG technique (Jina AI, 2024) where you run the whole document through a long-context embedding model FIRST, and split…
- LatencyThe delay between sending something and getting the response. Measured in milliseconds.
- LATERAL joinSQL feature: a subquery in the FROM clause that can reference columns from the left relation. SELECT * FROM users u, LATERAL…
- Lateral movementWhen an attacker who has gained a foothold on one machine spreads to other systems on the network.
- LaTeXTypesetting system built on top of TeX (Donald Knuth, 1978). LaTeX (Leslie Lamport, 1984) makes TeX manageable with macros…
- Lattice attackAn attack that uses lattice reduction to find short vectors, and often private keys, from partially leaked information.
- Lattice SemiconductorThe third FPGA maker, carved into the small low-power niche — and, unexpectedly, a favourite of the open-source crowd.
- LaunchDarklyThe company that turned an if statement into a subscription — and got large organisations to pay for it happily.
- Laura PoitrasThe filmmaker Snowden contacted first, because she already encrypted her email.
- Lauri LoveBritish-Finnish activist the US wanted to prosecute for intrusions during the Anonymous campaign after Aaron Swartz's death…
- Law of Demeter ("only talk to your friends")An object should only call methods on itself, its fields, its parameters, or objects it creates — not "train wreck" chains…
- Layer 2A network on top of the blockchain that executes transactions cheaply and only summarises the result downwards.
- Layer normalizationNormalization computed within each individual sample, across its features, instead of across the batch. Presented by Ba…
- layer-shellThe protocol that gives panels, wallpapers and lock screens a place in Wayland — surfaces anchored to a screen edge, stacked…
- Lazy evaluationComputation deferred until result actually needed. Default in Haskell (call-by-need). Manual in strict languages via…
- Lazy loadingLoad things only when needed instead of all upfront.
- LBANumber a disk's sectors 0, 1, 2 … in one long line and let the drive itself know where they physically sit.
- LBX (Low Bandwidth X)A 1996 X extension meant to make remote windows usable over a modem by compressing the protocol — which turned out to solve…
- LC3Low Complexity Communication Codec — the mandatory codec in Bluetooth LE Audio, and the first proper replacement for SBC.
- LCD (Liquid Crystal Display)The display tech that replaced CRTs in the 2000s — liquid crystals that block or pass backlight.
- LCP (Largest Contentful Paint)Core Web Vital measuring when the largest visible element finishes rendering — proxy for "the page feels loaded".
- LDACSony's 2015 Bluetooth codec, promising wireless hi-res audio by pushing up to 990 kbit/s through a radio link that would…
- LDAP (Lightweight Directory Access Protocol)Hierarchical directory service for users, groups and computers in enterprise environments.
- LDAP injectionLike SQL injection — but against LDAP directories. Manipulate search filters via unsanitised input.
- LDtkA modern, free 2D level editor from one of the designers behind Dead Cells — built as a friendlier successor to Tiled.
- Leaderless replicationA replication model without a designated leader/primary — any replica can accept writes and reads. Consistency is instead…
- LeafletA lightweight JavaScript library for interactive maps — around 40 kB with almost no dependencies.
- LeafnodeA small NNTP server for single users and small networks that fetches only the newsgroups somebody actually reads.
- Learning rateHow big the steps an ML model takes when updating weights — the most important hyperparameter.
- Least privilegeSecurity principle: give every user/service exactly as little access as needed to do its job.
- LeboncoinFrance's dominant classifieds site — "le bon coin" = "the good corner". Schibsted/Adevinta-owned, same model as Blocket.
- LED filterThe Amiga's low-pass filter, wired to the same switch as the power light — muffled sound in exchange for a brighter LED.
- LED printerAn electrophotographic printer that exposes the drum with a row of LEDs instead of a scanning laser.
- Ledger databaseA database type optimized for an immutable, verifiable transaction history — like a digital ledger. Every change is a new…
- LeecherA user who only downloads and never gives anything back — the scene's opposite of a supplier.
- Leeroy JenkinsThe 2005 video where a player charges into a raid while the group is still planning, screaming his own name, and gets…
- LeetspeakSwapping letters for numbers and symbols — 3 for e, 4 for a, 0 for o — born on 1980s BBSes as both a filter dodge and a…
- Legend of the Red DragonSeth Robinson's 1989 door game where you fought your way up to finally slay the red dragon — and flirted at the inn along…
- Legion of DoomOne of the best-known hacker groups of the 1980s, named after the villains in a Saturday-morning cartoon.
- Lehmer sieveNumber theory's purpose-built machine: nineteen bicycle chains spinning until the holes in all of them happened to line up…
- Leibniz wheelThe stepped drum Leibniz drew around 1673 — the dominant mechanism in calculating machines for almost three hundred years.
- LemmyFederated Reddit alternative written in Rust — speaks ActivityPub, every server is its own instance.
- Len SassamanCypherpunk and anonymity researcher who maintained the Mixmaster remailer and helped formulate LangSec.
- Length extension attackAn attacker can append data to a signed message and compute a valid signature without knowing the key.
- Length hidingKeeping the size of a message secret even when its contents are encrypted.
- Lenny DiCiccoKevin Mitnick's closest hacking partner in the 1980s, and eventually the man who handed him to the FBI.
- Lenny ZeltserSecurity instructor who made malware analysis something you can learn in a week rather than a decade.
- Lenore BlumAmerican mathematician and the first B in Blum Blum Shub, the random number generator with a security proof.
- LenovoThe Chinese PC maker that bought IBM's personal computer division in 2005 and inherited the ThinkPad, the black laptop with…
- LensDesktop app for Kubernetes cluster management. Electron-based. Mirantis-acquired 2020. Built-in Prometheus metrics, Helm…
- Lens effectA demo effect in which a round, magnifying lens slides across an image and warps whatever lies beneath it, like a magnifying…
- Lens flareThe rings of light and ghost blobs produced when light bounces between the glass elements of a lens — a camera artifact that…
- LenslokInfamous copy protection where the player held a plastic lens up to the screen to read a distorted code before the game…
- LEOWhen a British teashop company built its own computer to cost out cakes — the world's first business computer.
- Léo DucasFrench lattice cryptographer at CWI Amsterdam, co-author of BLISS, NewHope and Dilithium.
- Leo MarksBritish cryptographer who replaced SOE agents' poem codes with one-time keys printed on silk.
- Leon Battista AlbertiRenaissance architect who described a cipher disk with movable alphabets around 1467.
- Léon BolléeThe nineteen-year-old who cracked direct multiplication in 1889, won gold in Paris — and then left calculators for cars.
- Leonard AdlemanThe A in RSA, who coined the word "computer virus" and eleven years later solved a maths problem in a test tube.
- Leonard KleinrockThe UCLA queueing theorist whose lab became ARPANET's first node, and from which the internet's first word — "LO" — was sent.
- Leonard LaPadulaThe mathematician whose surname makes up half of the most cited security model in computing history.
- Leonard RoseUnix consultant known as Terminus whose case became one of the most argued-over of the 1990 US hacker crackdown.
- Leonardo Torres QuevedoThe Spaniard who built a chess-playing automaton in 1912 and described an electromechanical analytical engine with floating…
- Leonid LevinThe Kolmogorov student who discovered NP-completeness in the Soviet Union while Stephen Cook was doing the same in the West…
- Lernout & HauspieBelgian speech-technology company that became Europe's tech darling in the 1990s and turned out in 2000 to have invented…
- Lerp (linear interpolation)The function a + (b − a) · t, which picks a point on the straight line between two values and is plausibly the most-called…
- Les EarnestThe Stanford administrator who wrote finger so nobody had to walk the halls looking for people — and who had built one of…
- Leslie ComrieThe astronomer who realised accounting machines could do astronomy, and got sacked for running them after hours.
- Leslie LamportThe philosopher of distributed systems, who in passing invented two of security's most durable ideas.
- Leslie speakerA speaker cabinet that fires sound through a spinning horn and a spinning drum, so the tone swirls by pure mechanics.
- Less (Less CSS)A CSS preprocessor from 2009 by Alexis Sellier. It added variables, mixins, nesting and arithmetic at a time when CSS had…
- LessTifA free clone of Motif, written so Linux users could run Motif applications without paying for a licence.
- Lester S. HillAn American mathematician who in 1929 described a cipher that encrypts several letters at once using matrix algebra.
- Let's EncryptThe free, automated certificate authority that single-handedly made HTTPS the default on the web.
- Letterboxd"Goodreads for films" — log what you've seen, rate, review, follow friends. Beloved by Gen Z film Twitter.
- LetterboxingThe black bars above and below the image when a wide format is shown on a narrower screen.
- Level 3A US backbone carrier whose AS3356 is one of the networks the rest of the internet pays to reach.
- Level editorThe tool where the game world actually gets built — walls, enemies, lights and triggers placed by hand by someone who…
- Level of detail (LOD)Swapping an object's geometry for a simpler version the farther it sits from the camera, so the renderer never spends effort…
- Level streamingLoading and unloading parts of the game world at runtime so a large world fits in memory without loading screens.
- Leveled compactionThe compaction strategy where each level is roughly ten times larger than the one above and files within a level never…
- LexarThe memory-card maker that invented the "x" speed rating on CompactFlash and changed owners about as often as a USB stick…
- LexicalMeta's extensible text editor framework. Open-sourced 2022. Replacement for their own old Draft.js. Powers Facebook…
- LexiconThe Massachusetts company that sold some of the first digital delays and then defined what digital reverb sounded like for…
- LexmarkIBM's spun-off printer division, more influential in American IP law than in any printing technology.
- LFE (low-frequency effects)Low-Frequency Effects: the dedicated bass channel for explosions and rumble — the ".1" in 5.1.
- LFI (Local File Inclusion)A vulnerability where a web application lets user input decide which file to load. The classic is…
- LFOLow Frequency Oscillator — an oscillator too slow to hear on its own, used instead to turn other knobs for you.
- LFSR (linear feedback shift register)A shift register whose new bit is a linear function of some of the old ones: cheap in hardware, and exactly why it is…
- LG ElectronicsSouth Korea's other electronics giant, born as GoldStar in 1958, built the country's first radio and TV and now supplies…
- LGA socketLand Grid Array — CPU socket type where the pins are on the motherboard, not the CPU. Intel has used it since 2004 (LGA…
- LHAThe free Japanese archiver that became the de facto standard for packing files on the Amiga and across dial-up bulletin…
- Li GongJava's security architect at Sun, who replaced the original all-or-nothing sandbox with fine-grained, policy-driven access…
- Liam O MurchuIrish Symantec researcher who, with Eric Chien and Nicolas Falliere, took Stuxnet apart and showed that its real target was…
- libcC's standard library — printf, malloc, fopen, strlen, etc. Sits on top of the kernel and is "the C API" to the operating…
- libcacaC library that renders images and video as coloured text, the successor to the monochrome AA-lib.
- Libera.ChatThe IRC network for open source, founded in May 2021 when essentially the entire volunteer staff walked out of Freenode…
- libGDXA Java game framework running on desktop, Android and the web from one codebase — with no visual editor, deliberately.
- libinputThe library that interprets mice, touchpads, touchscreens and tablets for Wayland compositors and the X server alike…
- LibraryPre-written code that someone else made and that you can import and use.
- libsamplerateA C library for sample rate conversion, also known as Secret Rabbit Code, that made high-quality resampling free for anyone…
- libsndfileThe C library that reads and writes audio files for half the open-source audio world, so no program has to parse WAV headers…
- libsodiumModern crypto library: portable fork of Bernstein's NaCl. C + bindings to 25+ languages. High-level API that makes it hard…
- libSQLOpen-contribution fork of SQLite — started by Turso 2022 after the SQLite author (Richard Hipp) rejected external PRs.
- libvirtAn abstraction layer over hypervisors — one API and one XML definition whether KVM, Xen or LXC sits underneath.
- LifeforceA PC demo by Greek group ASD that won Assembly 2007 and showed how much atmosphere real-time 3D could carry.
- Lifetimes (Rust)Rust compile-time annotation describing how long a reference is valid. Written as 'a tag. Borrow checker uses lifetimes to…
- Light bakingComputing a scene's lighting once, offline, and storing the result in textures and probes so it costs almost nothing at run…
- Light leakingA rendering error where light appears where it should be blocked, typically when a wall is too thin for the method's…
- Light penThe pointing device you held against the screen — a light sensor that revealed where the electron beam happened to be.
- Light pre-passA deferred-lighting variant that stores only depth and normals, lights into a buffer, then re-renders geometry to apply…
- Light probeA point placed in the scene that stores the incoming light from every direction, so moving objects can pick up the same…
- Light propagation volumes (LPV)A 3D grid that indirect light is injected into and then propagated cell by cell, giving dynamic diffuse global illumination…
- LightDMCanonical's display manager from 2010, built so that the login screen is a swappable program — which is how Ubuntu, Mint and…
- LighthouseGoogle's tool for auditing a web page — performance, accessibility, SEO, best practices.
- LightmapA texture that stores precomputed lighting for static geometry, baked once so the runtime needn't recompute it every frame.
- LightmatterBuilds processors that compute with light instead of electrons to break through the data center's energy wall.
- Lightning CSSRust-based CSS parser + transformer + minifier. Devon Govett (Parcel creator), 2022. Standard CSS toolchain within Parcel…
- Lightning NetworkA payment layer on top of Bitcoin, live since 2018. It addresses the fact that the blockchain handles seven transactions per…
- LilyPondA music engraving program where you type the notes as text and compile them into a score, much as TeX does for mathematics.
- LimaLinux virtual machines on macOS. QEMU + Linux + Docker/containerd pre-configured. WSL-like experience on Mac. Akihiro Suda…
- Limelight NetworksThe Arizona CDN that spent two decades as Akamai's challenger, remembered mostly for a patent fight that went all the way to…
- LimeWireFile-sharing client for the Gnutella network that picked up where Napster left off, until a court shut it down in 2010.
- Limiter (audio)A compressor with its ratio turned up to infinity: nothing gets past the ceiling, however hard the signal pushes.
- LimitRangeKubernetes object that sets default resource requests/limits + min/max per pod or container in a namespace. Complements…
- LINEDominant messenger in Japan, Taiwan, Thailand — born after the 2011 tsunami when the phone network was down.
- Line levelThe signal strength audio gear uses to talk to other gear after the preamp — in two incompatible flavours, +4 dBu in the…
- Line matrix printerA line printer's speed with a dot matrix printer's freedom: an oscillating bank of hammers that dots the full page width one…
- Line of sight (LOS)The question of whether one point can "see" another with nothing in the way — the basis for enemies spotting the player.
- Line printerA high-speed impact printer that stamps out a whole line of text at once — the mainframe's workhorse from the 1950s to the…
- Linear approximationA relation between input and output bits that holds slightly more often than chance would suggest.
- Linear approximation table (LAT)A table of how well each linear combination of an S-box's input bits predicts each combination of its output bits.
- Linear blend skinningDeforms each vertex as a weighted sum of the influencing bones' matrices — the default method for skeletal animation, fast…
- Linear cryptanalysisLooks for relationships that happen to hold slightly more than half the time — and converts that bias into key bits.
- Linear density (BPI)The number of bits that fit along an inch of track — one of the two axes whose product is areal density.
- Linear hullThe set of all linear paths through a cipher, whose biases add up rather than being counted one at a time.
- Linear regressionThe simplest ML model: y = mx + b. Find the best line through data points.
- Linear serpentine recordingWriting tape in straight tracks that fold back and forth lengthwise, like a plough turning at the field's edge — the basis…
- Linear TechnologyAn analog chipmaker best known among hobbyists for a piece of free software.
- Linear timecode (LTC)SMPTE timecode recorded as an audio signal on its own track, so tape machines and video decks can agree on which frame they…
- Linear trailA chain of linear approximations, one per round, that together describe how a bit mask on the plaintext correlates with a…
- Linear-phase EQAn equaliser that delays every frequency by exactly the same amount, so filtering changes the tone but never the phase…
- LinearizabilityThe strictest single-operation consistency model: every operation appears to take effect atomically at a single point…
- LinecrunchA C64 trick that repeats or skips character rows mid-frame to scroll the text screen more smoothly than the hardware's fine…
- Link aggregation (LACP / bonding)Combine multiple physical network connections into one logical one — more bandwidth, redundancy.
- Link in bioTrend that emerged from Instagram's limit to one bio link. Drives the entire aggregator market (Linktree, Beacons). Standard…
- Link-local addressesIP addresses that only work within a single network segment — IPv4 169.254.0.0/16, IPv6 fe80::/10. Auto-assigned when DHCP…
- Linked listData structure where each element points to the next — scattered across memory rather than in one block.
- LinkedInProfessional network — founded in 2003 by Reid Hoffman, acquired by Microsoft in 2016 for USD 26 billion, today ~1 billion…
- LinkerThe program that stitches the compiler's object files into an executable and resolves every symbol that was still pointing…
- LinkerdThe service mesh that coined the term — Buoyant 2016, CNCF graduated 2021. Linkerd 2 (2018) was rewritten in Rust for…
- LinksysThe router brand whose blue-and-black WRT54G accidentally started the whole open router firmware movement.
- Linktree"Link in bio" service: one URL that leads to a page with multiple links. Built 2016 by Australian brothers. 50M+ users…
- LinnDrumThe drum machine with sampled real drums that gave 1980s pop its drum sound.
- LinodeOne of the first providers of cheap virtual Linux servers, and a developer favourite long before "cloud" became a sales word.
- LinotypeThe machine that cast whole lines of text in molten lead and shaped the world's newspapers for nearly a century.
- LinterTool that statically scans your code and finds bugs, suspicious patterns and style violations.
- Linus ÅkessonSwedish scener, known as lft, who makes demos on hardware nobody else took seriously.
- Linus TorvaldsFinland-Swedish programmer who created Linux in 1991 and Git in 2005. Two of the world's most-used pieces of software. BDFL…
- LinuxOpen source kernel that powers basically every server, Android phone, embedded device, and supercomputer.
- Linux kernelThe monolithic kernel system Linus Torvalds began in 1991. World's most-installed software — Android, every web server…
- LionAn optimizer Google found by letting a search algorithm comb the space of possible optimizers rather than designing one by…
- LiquibaseDatabase migration tool. Nathan Voxland, 2006. Define schema changes in XML/YAML/JSON/SQL changesets, run them in order…
- LiquidTemplating language created by Shopify in 2006. Safe (sandboxed) — lets customers write templates without executing…
- Liquid metal (TIM)Gallium-based thermal-interface material (TIM). 80+ W/mK thermal conductivity vs paste's 5-15. Standard in high-end gaming…
- Liquidity poolA shared reserve of two assets traded against each other by formula — the engine inside decentralised exchanges.
- LispOne of the world's oldest programming languages — John McCarthy, MIT, 1958. Famous for its parentheses and for code = data…
- List partitionPartitioning strategy: explicit list of values per partition. PARTITION p_emea VALUES IN ('SE','NO','DK','FR','DE'). Use…
- Listen backlogQueue size for fully established but not-yet-accepted TCP connections. When the backlog fills, new SYN+ACK or ACK is dropped…
- Listen serverA game server running inside one player's client, so the host both plays and referees.
- LISTEN/NOTIFYPostgreSQL's built-in pub/sub. Lets a transaction wake other connections up without them having to poll, in about thirty…
- ListProcAn early-nineties Unix list manager that let universities run LISTSERV-style mailing lists without an IBM mainframe.
- LISTSERVThe first software to run mailing lists automatically — subscribing, unsubscribing and distribution were all driven by…
- LitGoogle's web components library — successor to Polymer. Lightweight (5KB), TypeScript-first, reactive properties via…
- Lite-OnA Taiwanese component giant whose optical drives shipped under dozens of other brands.
- LiteStepThe shell replacement that from 1997 gave Windows an AfterStep look: Explorer swapped for modules, themes and virtual…
- Lithography (photolithography)Process to transfer patterns (the circuit) to a semiconductor wafer via light + photo-sensitive resist. Defines the entire…
- Little's lawThe average number of "things in the system" = arrival rate × average time they stay. L = λW.
- Live shoppingSelling products via live-streamed video where viewers can buy with one click during the broadcast. Enormous in China…
- Live2DJapanese technology that makes a flat 2D illustration turn its head, blink and breathe by deforming its parts rather than…
- LiveJournalA blogging platform started in 1999 by Brad Fitzpatrick — the same person who later wrote memcached to keep the site up. It…
- LiveKitOpen-source infrastructure for real-time video and audio, built on top of WebRTC.
- LivelockConcurrency bug where threads keep working but never make progress — they all retry each other forever. Distinct from…
- Liveness probeA health check in Kubernetes that determines whether a container is still "alive" or has hung. If it fails, the kubelet…
- LivewireLaravel's "write components in PHP, run them on the server, the client swaps the DOM" — like Hotwire but for Laravel.
- Living off the land (LOLBins)An attack technique where the attacker uses legitimate, already-installed system tools (PowerShell, WMI, certutil, PsExec)…
- LlamaMeta's open-weights LLM family — Llama 1 (Feb 2023, leaked on 4chan), Llama 2 (July 2023, commercial OK), Llama 3 (April…
- Llama 3Meta's open-weight LLM family, released April 2024. Llama 3 (8B + 70B), Llama 3.1 (July 2024, added 405B), Llama 3.2…
- llama.cppPure-C++ implementation of LLM inference — runs Llama, Mistral, Gemma and others on CPU, GPU (CUDA, Metal, Vulkan, ROCm) or…
- LlamaIndexRAG-focused framework — primitives for data ingestion, chunking, indexing and querying over your own data, from PDFs to SQL.
- LLDPLink Layer Discovery Protocol (802.1AB, 2005). Standard L2 protocol where devices announce identity + capabilities to…
- LLM (Large Language Model)An AI model trained on huge amounts of text that can generate, translate or reason with text.
- LLM agents ("agentic")An LLM in a loop — plans, calls tools, observes the result, plans the next step. The shift from "chatbot" to "colleague".
- LLM evalThe process of evaluating LLM output quality. Two categories: benchmark evals (MMLU, GPQA, SWE-bench — fixed datasets) +…
- LLM leaderboardPublic rankings of LLM performance. LMSYS Chatbot Arena (1.5M+ human votes), HuggingFace Open LLM Leaderboard, Artificial…
- LLM-as-judgeUse an LLM to grade outputs from another LLM — a cheap way to scale "human evaluation" from hundreds to millions of samples.
- LLMNR poisoningWindows asks the whole local network "does anyone know this name?" when DNS fails, and anybody is allowed to say yes. The…
- LLVMModular compiler infrastructure — Chris Lattner UIUC, 2003. Defines LLVM IR (intermediate representation) as a universal…
- LM hashLAN Manager's late-1980s password hash, built on DES and weak enough to crack in minutes.
- LMDB (Lightning Memory-Mapped Database)An embedded key-value store in roughly 10,000 lines of C, written by Howard Chu for OpenLDAP in 2011. The opposite of…
- LMMSA free DAW built around patterns and synths — roughly what FL Studio would be had it been written as open source.
- Load balancerDistributes traffic across multiple servers so none of them gets overloaded.
- Load pointThe reflective marker that tells a tape drive where recording begins — and its twin at the end of the tape.
- Load/store queueThe buffers that handle memory operations (loads and stores) in an out-of-order CPU and keep track of their order and…
- Loader musicThe music that played while a Commodore 64 game loaded from tape — often remembered better than the game.
- Loading screenThe picture that loaded first from tape and then kept the player company for the minutes it took to load the rest of the…
- LoadRunnerThe load-testing tool that replays thousands of virtual users against an application to find where it buckles.
- Local secondary index (LSI)A secondary index in a distributed database that is partitioned together with the main data (same partition key). Writes…
- LocaleThe setting that tells a program which language and regional conventions to use.
- localhost"This computer" — the name that maps to the loopback IP 127.0.0.1 (IPv4) or ::1 (IPv6).
- Localization (L10n)Adapting software for a specific region/language — translations, date formats, currency, right-to-left scripts. Distinct…
- localStorageBrowser API for storing small amounts of data (5-10 MB) per domain — persists until explicitly cleared.
- Lock escalationThe database trades thousands of row locks for a single table lock to save memory — and wipes out concurrency in one step.
- Lock timeoutMax time a query waits to get a lock before aborting. Default often unlimited (waits forever) — production tuning recommends…
- Lock-freeConcurrent code that doesn't use mutexes/locks — built on atomic operations (CAS).
- LocketiPhone widget app that shows live photos from close friends on your home screen. Launched January 2022, viral hit (top app…
- LockstepA networking model where every client runs the exact same deterministic simulation and sends only each other's inputs, not…
- LODLevel of Detail — swap a model for a simpler one once it is far enough away to cover ten pixels anyway.
- LOD cross-fadeInstead of switching level of detail on a single frame, both versions are drawn briefly, one fading in as the other fades…
- LodashJavaScript utility library. Fork of Underscore (2012, John-David Dalton). 200+ helper functions for arrays, objects…
- Log4Shell (CVE-2021-44228)Catastrophic vulnerability in the Java logging library log4j (Dec 2021) — just logging a string was enough to run arbitrary…
- Log4Shell (Log4j)CVE-2021-44228, December 2021. RCE in Apache Log4j via JNDI lookup in log messages. Standard string like…
- Logarithm tablesShelves of printed digits that turned multiplication into addition — and whose errors made Charles Babbage wish for a…
- Logarithmic depth bufferStoring depth on a logarithmic scale so precision lasts across the whole view, from centimetres up close to kilometres away.
- LoggingWriting out events and state from a running application for debugging and monitoring.
- Logic bombCode triggered by specific conditions — a date, an event, the absence of a check-in.
- Logic ProApple's DAW, descended from an Atari ST sequencer by Germany's C-Lab and now the default recording environment on the Mac.
- Logical decodingPostgreSQL feature: recode the WAL stream to logical changes (INSERT/UPDATE/DELETE events) instead of physical block diffs…
- Logical pianoA keyboard that solves syllogisms: type in the premises and the machine shows you which combinations survive.
- Logical propertiesCSS properties that describe position and size relative to the text's flow direction (inline/block, start/end) instead of…
- Logical qubitAn error-corrected qubit built from many physical ones — the measure that actually means something when comparing quantum…
- Logical replicationReplication at the row level (INSERT/UPDATE/DELETE events) instead of the block level — you can replicate selected tables…
- LogicomaA 2010s demogroup that makes 64k intros and open-sources the tools behind them.
- Logistic regressionClassification model — output is a probability (0-1) via the sigmoid function.
- Logit biasA parameter that lets you manually raise or lower the probability of specific tokens in an LLM's output — to force, or…
- LogitechThe Swiss-American company behind a large share of the world's mice, keyboards and webcams — the things you touch all day…
- LogMeInRemote-access company that swallowed LastPass and GoToMeeting and eventually renamed itself after the latter.
- logrotateThe tool that renames, compresses and eventually deletes old log files. It exists because a chatty service otherwise fills…
- LogstashThe L in ELK — the pipeline that takes log lines in any format whatsoever and emits structured JSON documents.
- Loïc DuflotFrench government researcher who showed that the most privileged mode on x86, System Management Mode, could be hijacked from…
- LokiGrafana Labs's log aggregator. "Like Prometheus, but for logs" — only indexes labels, not the text. Much cheaper than…
- LOKI97An Australian block cipher that was one of fifteen first-round candidates in the AES competition.
- LOLBASThe catalogue of signed Windows programs that can be made to do something entirely other than intended — download files…
- LonghornCloud-native distributed block storage for Kubernetes. Rancher (now SUSE), 2014. CNCF Incubating 2019. Replicates volumes…
- Longitudinal magnetic recording (LMR)The method where the magnetic grains lie flat in the plane of the platter — the hard drive's standard from 1956 to the…
- Look and feelHow an interface looks and how it behaves, treated as a thing that can be standardised, licensed, copied and, for a few…
- Look-at IKAn inverse-kinematics pass that turns the head, eyes or torso so a character follows a target with its gaze, layered on top…
- Lookahead (audio)A trick in which a dynamics processor delays the audio but not its own detector, so it sees a peak coming before it has to…
- LookerA BI tool that let analysts define their metrics once, in code, instead of in a hundred spreadsheets.
- Looking glassA public window into somebody else's router, so you can see what the internet looks like from their side instead of yours.
- LoomRecords your screen and webcam at once and hands back a shareable link — meant to replace the meeting that could just as…
- LoopConstruct that repeats code until a condition is met — for, while, forEach.
- Loop protectionSwitch features that protect against Layer 2 loops beyond STP. BPDU Guard, Loop Guard, Unidirectional Link Detection (UDLD)…
- Loopback interfaceA virtual network interface on a router/switch that's always up as long as the device is alive — it isn't tied to any…
- LooperAn effect that records a phrase and repeats it in a loop, so a lone musician can stack layer upon layer of themselves.
- Loose index scanAn optimization for DISTINCT and GROUP BY: instead of reading all index entries and eliminating duplicates, the database…
- Loose octreeAn octree variant whose node boxes are enlarged so that an object straddling a boundary still fits inside a single node.
- Loot tableA weighted list of what a defeated monster or opened chest can drop, and how often.
- LoRA (Low-Rank Adaptation)Low-Rank Adaptation — parameter-efficient fine-tuning. Microsoft paper, 2021. Freeze the base model, train only two small…
- LoRaWAN (Long Range Wide Area Network)Long Range Wide Area Network — a low-power protocol for IoT that sends small amounts of data over kilometers on unlicensed…
- Loren KohnfelderInvented the certificate in a 1978 undergraduate thesis, then handed Microsoft STRIDE two decades later.
- Lorenz cipherThe teleprinter cipher of the German high command — harder than Enigma, and reconstructed by a man who never saw the machine.
- LoroModern CRDT library in Rust for local-first collaborative apps. WASM bindings for the browser. Optimised for rich text +…
- Lorrie CranorResearcher who measured how people actually use security systems and found the rules often made things worse.
- Loss functionThe function that measures how wrong the model's output is — what gradient descent tries to minimise.
- Loss spikeWhen the training loss suddenly shoots up mid-run. Sometimes it recovers by itself, sometimes the model is ruined and you…
- Lossless compressionCompression where the original can be reconstructed bit for bit. The opposite of lossy formats like JPEG and MP3, which…
- Lossy compressionDiscarding information the eye or ear will not notice anyway — and thereby compressing far harder than would otherwise be…
- Lost updateConcurrency anomaly: two transactions read the same row, both modify based on read-value, the second write overwrites the…
- Lotus DevelopmentThe software house behind Lotus 1-2-3, the spreadsheet that gave businesses a reason to buy an IBM PC.
- Loudness Range (LRA)A figure in LU describing how much perceived loudness varies across a whole programme, from its quietest passages to its…
- Loudness warTwo decades of escalation in which records were mastered ever louder, until there was no dynamic range left to sacrifice.
- Louis CouffignalFrench mathematician who argued for binary calculating machines as early as the 1930s — and whose own attempts to build one…
- Louis GoubinFrench cryptographer who works both sides of the same chip: multivariate signature schemes, and attacks that read the key…
- Louis GuillouFrench engineer who made zero-knowledge proofs frugal enough for a smart card, and explained them with a cave and Ali Baba.
- LÖVE (love2d)A 2D framework where you write the whole game in Lua — from nothing to a window in a handful of lines.
- LovebyteAn online party devoted entirely to sizecoding, where 256 bytes counts as a generous budget.
- Low-level formattingDrawing the physical track-and-sector grid onto a blank disk — not creating a filesystem.
- Low-pass filterA filter that lets the lows through and attenuates everything above a cutoff frequency.
- Loyd BlankenshipThe Mentor — wrote the hacker manifesto in 1986 and, four years later, the role-playing book that sent the Secret Service…
- LPCThe C-flavoured, object-oriented language LPMud worlds were written in — and the one thousands of teenagers learned to…
- LPCAMM2Low Power Compression Attached Memory Module — a new replaceable memory form factor (JEDEC, 2023) for LPDDR5X in laptops. It…
- LPDThe oldest network printing protocol — Berkeley's line printer daemon, documented in RFC 1179.
- LPDDRLow-Power DDR — RAM optimized for mobile/laptop. Lower voltage (1.0-1.1V vs 1.2V), more aggressive power states. LPDDR5/5X…
- LPDDR5 / LPDDR5XLow Power DDR5 — the mobile DDR variant. Sits in smartphones, laptops with soldered RAM (Apple Silicon, Snapdragon X Elite)…
- LPILines per inch — how finely the grid of halftone dots is spaced when an image is printed, the print trade's counterpart to…
- LPMudThe Swedish MUD server whose world was written in its own C-like language, LPC, and extended while players were inside it.
- lprThe BSD Unix command that hands a file to the print queue — the client half of the lpd spooler.
- LRULeast Recently Used — discard whatever has sat untouched longest, on the bet that what was just used will be used again soon.
- LRW modeA 2002 tweakable block cipher built from an ordinary block cipher, later superseded by XTS for disk encryption.
- ls-lRThe file at the top of an FTP server listing everything in the archive — the table of contents from before search engines.
- LSDjThe music tracker that turns an ordinary Game Boy into an instrument — the core of the modern chipmusic scene.
- LSI LogicThe chip company that started with custom silicon and ended up as the controller in nearly every server room.
- LSM-treeLog-Structured Merge tree — the data structure behind modern write-heavy databases. Writes land in RAM first (memtable), get…
- LSP (Language Server Protocol)A protocol that separates language support from the editor. Published by Microsoft in 2016 alongside VS Code and since…
- LSTM (Long Short-Term Memory)Recurrent neural network with "gates" that let it remember long-term — the workhorse for sequence modeling 1997-2017.
- LTE (4G)The mobile generation that made the network all-IP and made mobile broadband ordinary.
- LTFS (Linear Tape File System)An open standard that puts a self-describing filesystem on LTO tape, so a cartridge mounts like a slow USB drive instead of…
- LTO (Linear Tape-Open)An open tape standard from 1998, created by HP, IBM and Quantum to break the dependence on proprietary tape formats. Still…
- LTSPThe Linux Terminal Server Project, the way to make a room full of cast-off PCs boot over the network and run everything on…
- LuaLightweight scripting language from PUC-Rio, Brazil (1993) — designed to be embedded in other applications. ~100 KB binary…
- LuantiA free C++ voxel engine whose actual games are written as Lua mods — better known by its old name, Minetest.
- LuauRoblox's own evolution of Lua 5.1, with gradual typing and a faster interpreter — the language millions of teenagers wrote…
- Luca De FeoItalian mathematician who created SIDH with David Jao in 2011 – and after its collapse in 2022 kept building isogeny…
- LucasArtsLucasfilm's games division, best remembered for point-and-click adventures and the engine underneath them.
- Lucent TechnologiesAT&T's equipment arm, with Bell Labs in tow — the most widely held stock in America during the dotcom years and a textbook…
- Lucia (Lucia Auth)Minimalist TypeScript auth library — just session management, you control the rest. The author deprecated the library in…
- LuciferIBM's early-1970s block cipher — the first civilian Feistel cipher and the direct ancestor of DES.
- Lucky MicrosecondsThe 2015 attack showing that Amazon's s2n had defended itself against Lucky Thirteen with random delays — and that…
- Lucky ThirteenA 2013 timing attack that exploits how TLS computes the MAC over CBC-padded records, so that small timing differences leak…
- Ludgate's analytical machineThe paper design published in 1909 by Irish accountant Percy Ludgate — the world's second analytical engine, with a…
- LUFSLoudness Units relative to Full Scale — a measure of how loud something is perceived to be, not just how high its peaks…
- Luigi MenabreaThe Italian officer whose paper on the Analytical Engine became the text Ada Lovelace translated, annotated and tripled in…
- LUKS (Linux Unified Key Setup)The standard disk-encryption format on Linux — a header format layered over dm-crypt.
- LumenUnreal Engine 5's real-time global illumination and reflection system, with no baked lightmaps.
- Lumen TechnologiesFormerly CenturyLink — a rural Louisiana phone company that bought its way into one of the world's largest fibre networks.
- LunarStormThe Swedish community an entire generation of teenagers lived inside during the first half of the 2000s, built years before…
- LurkerPassive consumer: reads a forum/community without posting. "90-9-1 rule": 90% lurkers, 9% occasional posters, 1% power users…
- LustreParallel filesystem for HPC and supercomputers — when you need TB/s of aggregate throughput to thousands of client nodes…
- LUTA lookup table mapping every incoming colour to an outgoing one — colour grading as a finished table rather than a…
- LuxorA radio and TV factory in Motala that, somewhat improbably, became Sweden's biggest home computer maker with the ABC 80.
- LV2The Linux world's open standard for audio plugins, where each plugin describes itself in an RDF file rather than in compiled…
- LVMLinux Logical Volume Manager. Abstraction layer between physical disks and filesystem. Three concepts: Physical Volume (PV)…
- lwmElliott Hughes's window manager that "tries to keep out of your way": no icons, no panel, barely a root menu, just a frame…
- LXDELightweight X11 Desktop Environment: a frugal GTK-based desktop for the machines GNOME and KDE had left behind.
- LycosCarnegie Mellon search engine that grew into one of the big 1990s web portals and then a textbook case of dot-com valuation.
- LyftUber's biggest US competitor — ~30 % US market share. Known for the pink-mustache branding and the "fist-bump greeting" in…
- Lyon PlayfairScottish chemist and politician who championed Wheatstone's digraph cipher and ended up giving it his name.
- Lyra2A Brazilian memory-hard password hash built on a sponge, better known among cryptocurrency miners than sysadmins.
- LysKOMThe Lysator computer club's free rewrite of KOM, which turned the conferencing system into a networked client and server…
M
- _MOTIF_WM_HINTSAn X11 property from Motif that lets a program ask the window manager to drop the frame — and that outlived Motif by decades.
- .mwmrcThe text file where mwm keeps its menus, key bindings and mouse buttons: everything that is an action rather than a colour…
- AMD Instinct MI300AMD's answer to Nvidia H100 — MI300X (GPU-only, 192 GB HBM3) and MI300A (APU with CPU + GPU). Launched December 2023.
- AMD MI300XAMD's first AI GPU that truly competed with Nvidia H100. Launched December 2023. 192 GB HBM3 (vs H100's 80 GB) — can run…
- Apache MavenJava's declarative build system and package manager — Sonatype/ASF, 2004. pom.xml describes the project, dependencies…
- Local timeline (Mastodon)A Mastodon feed showing all public posts from users on the same instance, in chronological order. It gives the instance a…
- M-94The US Army's 25-disk cylinder cipher, adopted in 1922 and in use well into the 1940s.
- M-PesaA Kenyan mobile money service from 2007 that turned the basic phone into a wallet and bank account for millions of people…
- M.2Small form factor for SSDs (and Wi-Fi cards) — directly on the motherboard, no cable.
- M.2 heatsinkA heatsink (often a metal plate with a thermal pad) mounted on an M.2 SSD to keep the temperature down. Increasingly…
- M.2 slotA small slot for modern SSDs and WiFi/WWAN modules. Replaced mSATA. An M.2 slot can carry either NVMe (PCIe) or SATA — a…
- M.2 SSDCard form factor for SSD (+ WiFi cards, cellular modems). 22mm wide. Length variants: 2230, 2242, 2260, 2280, 22110…
- M1Apple's first in-house system-on-chip for the Mac, launched in November 2020. The Intel-to-ARM transition the industry…
- Maas-Neotek botsA family of programmed players that Michael Mauldin turned loose on TinyMUD around 1990, the chatterbot Julia being the…
- MAC addressThe hardware address on your network card — fixed (mostly) and unique to the device.
- MAC address tableThe switch's table of which MAC address is behind which port. It's the basis for all switching: the switch learns the…
- MAC floodingSend thousands of fake MAC addresses to a switch — the CAM table fills up, the switch falls back to broadcast mode.
- MAC tableCAM table (Content Addressable Memory) on switch that maps MAC addresses to ports. Built via learning: switch sees…
- MAC-then-encryptThe construction of computing a MAC over the plaintext and then encrypting both together, an ordering that proved fragile.
- Machine codeThe actual numbers the processor reads — everything else we call programming is a layer on top of this.
- Machine Identification CodeThe grid of barely visible yellow dots that colour laser printers stamp across every page they produce, encoding serial…
- Machine learning (ML)Computers that learn from data instead of following explicitly programmed rules.
- MachineAccountQuotaThe setting that lets any domain user create ten computer accounts. It has defaulted to ten since 2000 and is the…
- MacintoshThe computer that made the graphical interface something ordinary people could buy — introduced with a commercial directed…
- Macintosh ToolboxThe routines in the Macintosh ROM that gave every program windows, menus, dialogs and text fields for free — and in the same…
- Mackie ControlA control-surface protocol that became the de facto standard for driving a DAW's mixer with real, motorised faders.
- macOSApple's desktop operating system — a certified Unix underneath an interface that gives no sign of it.
- MacroCode that generates code. C preprocessor (#define), Lisp/Scheme s-expression macros, Rust declarative + procedural macros…
- MacromediaThe software house behind Flash, Shockwave and Dreamweaver — which is to say, behind roughly half of how the web looked and…
- MacronixTaiwanese NOR and ROM maker that has spent decades burning Nintendo games into silicon.
- macvlanA Linux feature that creates several virtual interfaces on top of one physical card, each with its own MAC address. The…
- MacXApple's own X server for the classic Mac OS, released in 1990, which let Unix programs out on the network open as ordinary…
- Maddie StoneProject Zero researcher who counts the zero-days attackers actually use, and points out how often they are old bugs in a new…
- MADIMultichannel Audio Digital Interface — 64 audio channels down a single coaxial cable, standardised as AES10 in 1991.
- MAE-EastThe exchange point outside Washington that for a while carried an unreasonable share of the world's internet traffic.
- MagecartFamily of attacks against e-commerce — inject JS into checkout pages to steal credit card details.
- MAGENTAA block cipher from Deutsche Telekom that was submitted to the AES process in 1998 and was eliminated in the first round.
- Magic LeapThe Florida AR company that raised billions on a concept video of a whale in a school gym, and then had to ship actual…
- Magic linkPasswordless flow: user types in their email, gets a short-lived link that signs them in when clicked. Slack, Medium…
- Magic numberUnexplained numeric constant in the middle of code — if (status == 17). A classic code smell.
- Magic numbersHard-coded numeric constants without a name or explanation in the code. Classic code smell. if (status == 7) instead of if…
- MagitA Git interface for Emacs, started by Marius Vollmer in 2008 and long maintained by Jonas Bernoulli. Regularly described as…
- MagmaThe 64-bit block cipher in the Russian standard GOST R 34.12-2015, with a 256-bit key.
- Magnavox OdysseyThe world's first home console: no processor, no sound, no score — and plastic sheets to tape onto the television screen.
- Magnetic domainA region of a magnetic material where every atom points the same way — the smallest unit whose direction a storage surface…
- Magnetic stripeThe black band on the back of a card, where data sits magnetised across three tracks.
- Magnetic tapeDeclared dead since the 1980s and still the cheapest way to store a petabyte you rarely need to read.
- Magneto-optical discMedia that writes with laser heat plus a magnetic field but reads optically through the Kerr effect — nearly indestructible…
- Magneto-optical Kerr effectPolarised light bouncing off a magnetised surface twists slightly depending on the magnetisation's direction — this is how…
- MagnetographyA printing process that writes the image with magnetism rather than light, which forces the toner to contain iron in order…
- MailchimpPioneer of self-service email marketing — the free tier made it the indie business favourite. Bought by Intuit in 2021 for…
- MailgunTransactional email API. YC W11, 2010. Acquired by Rackspace 2012, spun off 2017, acquired by Sinch 2021. Competes with…
- Mailing listAn address that forwards every message to all subscribers — the network's oldest form of group discussion.
- mailtoolThe OpenWindows mail client in DeskSet, which attached files using Sun's own headers before MIME existed, and so turned "Sun…
- MailtroA small intro whose only job was to advertise a BBS or a trading contact.
- Main character of TwitterPerson who dominates Twitter discourse on a specific day — either through viral stupidity, controversy, or sudden fame. "You…
- MainframeNot the fastest at computing, but the best at never breaking and at moving unimaginable quantities of data in and out.
- MajordomoThe free mailing list manager that brought LISTSERV's idea from the IBM world to Unix servers.
- makeThe original build automation tool — Stuart Feldman wrote it at Bell Labs 1976. Define targets, dependencies, recipes. Tabs…
- Make Money FastThe chain letter that roamed Usenet from the late 1980s and lent its name to an entire genre of online scam.
- MakefileConfiguration file for make. Defines targets (what to build), dependencies (what's needed), recipes (commands). Tabs are…
- Makeup gainA fixed boost after the compressor that restores the level compression took away — and the most common reason compression…
- Maksim YakubetsThe Russian behind Evil Corp and the Dridex banking trojan, with a five-million-dollar bounty on his head.
- Malcolm WilliamsonThe third GCHQ cryptographer, who found the equivalent of Diffie-Hellman key exchange two years before it was published.
- MalleabilityThe property that a ciphertext can be altered in predictable ways so the plaintext changes, without anyone needing the key.
- Mallock machineAn analog machine that solved systems of equations by letting alternating current stand in for the mathematics.
- MalwareUmbrella term for all malicious software — viruses, trojans, worms, ransomware, spyware, rootkits.
- MalwarebytesThe tool generations of family tech support ran after the antivirus had already missed the infection.
- MambaSequence model built on selective state space models instead of attention, with cost linear in sequence length. Published in…
- MAMR (microwave-assisted magnetic recording)Microwave-assisted magnetic recording, which uses a spin-torque oscillator to shake magnetic grains into flipping more…
- Manchester BabyThe first machine to run a program held in its own memory — on 21 June 1948, for 52 minutes.
- Manchester Mark 1The machine that grew out of the Baby, and the first anywhere that could recompute an address while the program was running.
- MandiantThe firm large companies call once the breach has already happened, and the one that turned nation-state attribution into a…
- MandrivaFrance's Mandrake Linux, the distribution that made Linux installable by ordinary people around the turn of the millennium.
- Manfred SchroederGerman physicist at Bell Labs who invented digital reverberation and co-founded the speech coding inside every mobile phone.
- Manger's attackA 2001 attack showing that a single leaked bit from error messages is enough to decrypt RSA-OAEP ciphertexts.
- Maniacs of NoiseDutch music collective that scored a large slice of the C64's late game catalogue.
- MantineFull React component library with 100+ components, hooks, form validation, dark mode. Vitaly Rtishchev, 2021. Quickly grew…
- Manuel BlumVenezuelan-born theorist who made complexity theory the foundation of cryptography — and supervised half the field.
- MapboxA mapping platform built on open data that made vector tiles standard — then closed its source.
- MapKitApple's framework for embedding maps in apps — panning, pins, routes and overlays without running your own tile stack.
- MapNotifyThe X11 events MapNotify and UnmapNotify announce that a window has become eligible to appear on screen, or has stopped…
- MappingNotifyThe event the X server broadcasts to every client when the keyboard, modifier or pointer-button mapping changes, telling…
- MapRThe third Hadoop vendor — the one that rewrote the filesystem instead of packaging Apache's.
- MapReduceGoogle's programming model for running batch jobs across thousands of machines without the developer thinking about…
- MapRequestThe X11 event a window manager receives instead of a program actually showing its window — the first question asked in every…
- Marc AndreessenWrote, as a student, the browser that showed images inline — the seemingly small move that made the web legible to everyone.
- Marc MaiffretHigh-school dropout hacker who co-founded eEye Digital Security and gave the Code Red worm its name.
- Marc RogersBritish-born hacker who long ran security at DEF CON and hacked a Tesla Model S on stage in 2015.
- Marc StevensDutch cryptanalyst who turned MD5 and SHA-1 collisions from theory into working attacks.
- Marc Weber TobiasAmerican lawyer and lock expert who treats mechanical locks like any other piece of vulnerable software.
- MarchantCalifornian calculators pushed to a mechanical extreme no other manufacturer reached — and whose chief engineer left to…
- Marching cubesAn algorithm that turns a 3D scalar field into a polygon mesh by deciding, cube by cube, where a surface crosses the grid.
- Marching squaresThe two-dimensional cousin of marching cubes: it traces contour lines through a grid of scalar values, one cell at a time…
- Marco PoloAsynchronous-video-messaging app. Send short videos to friends/groups, recipient sees when they want. "Video walkie-talkie"…
- Marcus HutchinsBritish malware analyst who halted WannaCry by registering a domain for about ten dollars — and was arrested three months…
- Marcus RanumOne of the fathers of the firewall, and ever since one of its most sceptical critics.
- Marek Marczykowski-GóreckiPolish developer who took over leadership of Qubes OS when its founder, Joanna Rutkowska, stepped back.
- Margaret HamiltonLed the software for Apollo's guidance computer — and coined the term software engineering to get the discipline taken…
- MariaDBMySQL fork that Michael "Monty" Widenius (the MySQL creator) started in 2009 after Oracle's acquisition of Sun/MySQL. The…
- MariaDB MaxScaleMariaDB's own database proxy: load balancing, query routing and automatic failover in front of a cluster. The same role as…
- Marian RejewskiWorked out the internal wiring of the Enigma in 1932 without ever having seen inside one.
- Mark AbenePhiber Optik — the New York teenager who knew the phone company's switches better than its own technicians, and got a year…
- Mark CoxBritish developer who turned open-source vulnerability handling into a craft with procedures.
- Mark CurpheyBritish security figure who founded OWASP in 2001, back when web application security was barely a discipline of its own.
- Mark DowdAustralian vulnerability researcher, co-author of the standard text on security code review, and the man who weaponised a…
- Mark ErmolovRussian hardware researcher who, with Maxim Goryachy, took Intel's Management Engine apart piece by piece, right down to the…
- Mark KleinThe AT&T technician who showed that NSA wiretapping had a street address: 611 Folsom Street, San Francisco.
- Mark LudwigPhysicist who printed working viruses as source code in books, and argued it was a matter of free speech.
- Mark McCahillLed the University of Minnesota team that built Gopher in 1991, the year before the web took off.
- Mark RussinovichThe Windows expert who co-founded Sysinternals and, in 2005, caught Sony BMG installing a rootkit from music CDs.
- Mark SeabornGoogle engineer who in 2015 turned Rowhammer from an academic reliability problem into a way of getting root.
- Mark sensingPencil marks read electrically, on the grounds that graphite conducts and keypunch operators draw a salary.
- Mark ZuckerbergStarted Facebook at Harvard in 2004 and has led the company through every transformation since — including the rename to…
- MarkdownPlain-text formatting that generates HTML. John Gruber + Aaron Swartz, 2004. **bold**, # heading, [link](url). De-facto…
- Marker traitA Rust trait without methods, used purely as a type-level signal. Send (safe to transfer across threads), Sync (safe to…
- Markov cipherAn iterated cipher in which the probability of a difference propagating through a round depends only on the input…
- Markus FriedlGerman OpenBSD developer, one of OpenSSH's founders, and the person who taught it the second version of the SSH protocol.
- Markus HessWest German hacker who broke into US military computers in 1986–87 and sold the results to the KGB — undone by a 75-cent…
- Markus JakobssonCryptographer and phishing researcher who, with Ari Juels, coined the term "proof of work" in 1999.
- Markus KuhnGerman researcher at Cambridge who showed how much displays leak — and taught the Unix world to use UTF-8.
- MarqetaModern card-issuing platform whose API can spin up a payment card in a second — the engine behind many apps' virtual cards.
- MARSIBM's AES candidate, one of five finalists in 1999, built around a Feistel core wrapped in unkeyed mixing rounds.
- Mars (demo)Tim Clarke's 1993 DOS demo that let you fly freely over a red voxel landscape — and sent thousands of hobby coders off to…
- Marsh RayResearcher who showed in 2009 that TLS renegotiation let an attacker splice their own traffic onto the front of someone…
- Martín AbadiArgentine computer scientist who turned security protocols into something you could prove things about, then brought the…
- Martin GalwayThe Ocean Software composer who coaxed the SID chip into playing sampled sound it was never built to handle.
- Martin HellmanOne half of Diffie–Hellman — and the author who has most stubbornly insisted a third name belongs on the paper.
- Martin RoeschAmerican security engineer who wrote Snort in 1998, the open-source intrusion detection system whose rule syntax became the…
- Martin WibergShrank the difference engine to the size of a sewing machine and then used it to publish the tables nobody else could face…
- Marvell TechnologyThe chip company inside your hard drive, your SSD and your switch, even though nobody has ever bought a gadget because the…
- Marvin attackA timing-based revival of Bleichenbacher's padding oracle against RSA PKCS#1 v1.5, published in 2023 and still very much…
- Marvin MinskyOne of AI's founders — and author of the book widely held to have stalled neural network research for a decade.
- Mary Ann DavidsonOracle's long-serving chief security officer, best remembered for a 2015 blog post asking customers to stop looking for…
- Mary Ann HortonThe Berkeley programmer who wrote uuencode and terminfo, specified the Usenet article format, and wired the ARPANET mailing…
- MaskingSplitting every secret intermediate value into random shares, so that a power measurement of a single step reveals nothing…
- MasParLate-1980s supercomputer maker whose MP-1 packed up to 16,384 simple processors marching in lockstep — SIMD taken to its…
- MASQUEMultiplexed Application Substrate over QUIC Encryption — an IETF family of proxy/tunnel methods over HTTP/3 (CONNECT-UDP…
- Mass assignmentVulnerability: the framework takes the entire request body and assigns fields directly — including ones the user shouldn't…
- Mass followAuto-script that follows hundreds/thousands of accounts to trigger follow-backs. Mainstream growth hack 2012-2018, mostly…
- Mass-block (Bluesky)Bluesky feature: block 100,000+ accounts via a single subscribe to a curated blocklist. Game-changer for moderation fatigue…
- Mass-spring systemA simulation model in which an object is a network of point masses joined by springs and dampers.
- MASSCOMPReal-time Unix for the lab and the factory floor — Unix back when Unix wasn't thought capable of hard timing.
- Massive (synthesizer)Native Instruments' 2007 wavetable synth, which became the sound of dubstep and taught a generation of bass producers what…
- Massive EntertainmentThe Malmö studio that went from real-time strategy in rural Sweden to Ubisoft's big open worlds on its own engine.
- Master keyThe root key of a key hierarchy, rarely used for encryption directly.
- Master programmer (ENIAC)ENIAC's control flow lived in a cabinet of its own: ten counters keeping track of how many times a loop still had to run…
- MastercardVisa's closest rival among the card networks, founded by banks that had no intention of leaving the market to Bank of…
- MasteringThe last stop between a finished mix and a release: level, tone and running order are adjusted so the songs sit together and…
- Masters of DeceptionA New York hacker group whose feud with the Legion of Doom ended in a federal prosecution in 1992.
- MastodonFederated microblog platform — open source (AGPL), launched in 2016 by Eugen Rochko, made popular in 2022 in the wake of…
- Mastodon instanceA single Mastodon server. Users pick an instance at signup; it's their "home" but they can follow accounts on other…
- Maston BeardThe engineer who built the electronics of CSIRAC while Pearcey drew up the architecture.
- Mat HonanThe Wired journalist whose digital life was wiped in about an hour in 2012 because someone wanted his three-letter Twitter…
- MatCapA pre-rendered sphere image sampled by the surface normal in view space — fast stylized shading that ignores the scene's…
- MatchboxThe 2002 window manager for handhelds in which every window fills the screen, because 240×320 pixels have no room for…
- MatchmakingThe service that assembles players into online matches based on skill, latency and waiting time.
- MATEGNOME 2 under a new name: the 2011 fork that kept the panels, menus and Metacity when GNOME moved on to Shell.
- Material DesignGoogle's attempt to give flat design a physics: surfaces with thickness, stacked at heights, and shadows that mean something.
- Material instanceA lightweight variant of a parent material that overrides only parameters, without recompiling the shader code.
- Material UI (MUI)React component library that implements Google's Material Design (2014). Hjarne Steffjenakker 2014; now the MUI org. ~50…
- MaterializeStreaming database — run SQL on live data streams, materializing views that update incrementally on every event. Frank…
- MATERIALIZED CTEA PostgreSQL keyword (WITH ... AS MATERIALIZED / NOT MATERIALIZED) that controls whether a CTE is computed once and…
- Materialized pathA way to store tree structures in a relational database where each node saves the full path from the root as a string, e.g…
- Materialized viewStored result of a query — read like a regular table, but refreshed (manually or automatically) when the underlying data…
- Materialized view refreshPostgreSQL mechanism: snapshot of a query result stored as a table. Must be explicitly refreshed — not auto-updated like…
- Mateusz JurczykPolish security researcher, better known as j00ru, who has found hundreds of Windows kernel bugs by having an emulator watch…
- Mathematical Tables ProjectAn American unemployment relief scheme that put 450 people to work computing by hand, and became the largest human…
- MathWorksThe company that turned a free teaching tool into one of engineering's most expensive licences.
- Mathy VanhoefBelgian researcher who showed three times in four years that Wi-Fi security was broken in the standard itself.
- Mati AharoniThe Israeli security trainer ("muts") behind BackTrack and Kali Linux — the distributions that put hundreds of attack tools…
- MATLAB"Matrix laboratory" — written so that students would not have to learn Fortran before touching a matrix.
- MatrixOpen decentralised real-time communication protocol — federated home servers, end-to-end encrypted rooms (Olm/Megolm)…
- Matrix bridgeComponent that plugs other chat networks (IRC, Discord, Slack, Telegram, WhatsApp, Signal) into Matrix. Matrix-side users…
- Matrix SpaceA Matrix feature: a "space" groups multiple rooms into a hierarchy, much like a Discord server gathers channels. Introduced…
- MatroxThe Montreal company whose graphics cards had the sharpest picture of the 1990s, and which stepped out of the 3D race to…
- Matryoshka embeddingEmbeddings trained (Matryoshka Representation Learning) so the most important information is concentrated in the first…
- Matsui algorithmThe search algorithm that turned linear approximations of DES from theory into an actual break.
- Matt BishopUC Davis professor whose textbook taught a generation of security students to start with formal models before reaching for…
- Matt BlazeThe researcher who showed in 1994 that the Clipper chip's backdoor could be bypassed — and later did much the same to…
- Matt CurtinAmerican security consultant who helped lead DESCHALL, the first public demonstration that DES could be broken.
- Matt FranklinAmerican cryptographer who, with Dan Boneh, made identity-based encryption practical in 2001.
- Matt GraeberThe researcher who showed how much damage you can do on Windows using only what is already installed.
- Matt GrayBritish C64 composer whose Last Ninja 2 soundtrack still gets played more often than the game itself.
- Matt Miller (skape)The exploit researcher who wrote the attack tooling first and then went to Microsoft to make it harder to use.
- Matt SuicheFrench memory-forensics researcher who showed that Windows hibernation writes a complete copy of RAM to disk, readable by…
- Matt TaitFormer GCHQ analyst and Project Zero researcher who became one of the most-read voices on where technical fact ends and…
- MatterA unified smart-home standard (Connectivity Standards Alliance, 2022) meant to make gear from different vendors work…
- Matter.jsA 2D physics engine written in plain JavaScript, for games and interactive demos that need to run in the browser without…
- MattermostA self-hosted open-source chat tool, deliberately built as a Slack alternative right down to the keyboard shortcuts. Written…
- Matthew BevanWelsh hacker known as Kuji, cast as the mastermind behind the 1994 break-ins at the US Air Force's Rome Laboratory.
- Matthew GarrettThe Linux developer who wrote shim in 2012, the tiny first-stage loader that lets mainstream Linux distributions still boot…
- Matthew GreenJohns Hopkins cryptographer who has become the field's most-read explainer whenever a big encryption story breaks.
- Matthias EttrichThe German student who suggested on Usenet in October 1996 that somebody should build a consistent desktop for Unix — and…
- Matyas–Meyer–OseasA recipe for turning a block cipher into a one-way compression function: the chaining value becomes the key, the message…
- Maurice WilkesWent home from a summer school in Philadelphia and built the first stored-program computer that did useful work every day.
- MausNetA German network of bulletin boards running the MAUS software — one of several home-grown alternatives to FidoNet before the…
- Mavis BateyThe Bletchley Park codebreaker whose decrypt set up the Battle of Cape Matapan.
- Max ButlerIceman, who hacked his way to a monopoly on the black market for stolen credit cards.
- Max MathewsThe Bell Labs engineer (1926–2011) who got a computer to generate music in 1957 and is usually called the father of computer…
- Max NewmanThe topologist whose lecture set Turing off, and who later commissioned both Colossus and the Manchester Baby.
- Max/MSPA visual programming language where you drag cables between boxes until it sounds right — and the main reason artists have…
- MaxiCodeA UPS 2D barcode from 1992, built to be read at full speed on a moving parcel belt.
- Maxim IntegratedThe Silicon Valley analog specialist that rival Analog Devices swallowed in 2021.
- MaximizeLetting a window fill the whole work area with one click, and getting it back exactly as it was: a button that has meant…
- Maximus (BBS)BBS software built for the FidoNet world that became one of the few serious options on OS/2.
- MaxisThe studio behind SimCity and The Sims, which built an entire genre on games you can't win.
- MaxtorA hard drive maker that grew by buying its rivals and ended up being bought by the biggest one.
- Maze generationAlgorithms — recursive backtracker, Prim's, Kruskal's, Wilson's — that carve a grid into a perfect maze with exactly one…
- Maze WarA 1973 maze game that was first both with a first-person view and with players shooting each other over a network.
- MBoneA virtual network layered over the internet from 1992 that tunnelled multicast traffic between the few sites able to handle…
- mboxUnix's oldest way of storing email: every message one after another in a single text file, separated by lines beginning with…
- McAfeeThe antivirus company that kept its founder's name long after he left, and has changed owners more often than most people…
- MCCPMUD Client Compression Protocol — compressing the stream of text coming out of a MUD server.
- McCulloch–Pitts neuronThe 1943 mathematical nerve cell: binary inputs, a threshold, and the proof that a network of them can compute any logical…
- MCP (Model Context Protocol)Anthropic's open protocol for connecting LLMs to tools, data, systems. Launched November 2024. Rapidly accepted as standard…
- MCP toolA server that exposes tools/resources/prompts via the Model Context Protocol (Anthropic 2024). MCP clients (Claude Desktop…
- mcvaxThe Mathematisch Centrum VAX in Amsterdam — Europe's central hub for UUCP mail and Usenet through the 1980s.
- mcwmA Swedish-written minimalist window manager with no title bars, driven almost entirely from the keyboard and built directly…
- MD DataSony's 1993 data version of MiniDisc — 140 MB on a shuttered magneto-optical disc, meant to succeed the floppy.
- MD2Ron Rivest's first hash in the MD family, built for 8-bit processors and every bit as slow as that suggests.
- MD3Quake III Arena's model format, which stores animation as a full set of vertex positions per frame and holds body parts…
- MD4The hash function broken almost immediately, whose design nevertheless became the template for MD5, SHA-1 and RIPEMD.
- MD5Hash algorithm from 1991 — 128 bits. Cryptographically broken since 2004 but still used for checksums (not security).
- MD5 collisionTwo different inputs that produce the same MD5 hash, and a method that made it deliberate.
- mdadmLinux software RAID utility. Manage md (multiple device) kernel driver. Supports RAID 0, 1, 5, 6, 10, linear. Neil Brown…
- MDC-2IBM's 1988 hash function that runs two DES encryptions side by side to produce a digest twice as wide as the cipher's block.
- MDCT (modified discrete cosine transform)The overlapping frequency transform underneath almost every lossy audio codec since the 1990s.
- MDI (Multiple Document Interface)The window model in which an application owns one big frame window and every open document is a child window confined inside…
- MDROutsourced security operations: an external team watches, hunts and responds to threats in your environment around the…
- MDS matrixA linear mixing step that spreads a change in a few bytes across many.
- MDXMarkdown that is allowed to import and render React components in the middle of the prose.
- Me too!The Usenet reply that quoted a hundred-line post in full and then added two words — and came to stand for AOL's arrival on…
- Mead & Conway revolutionCarver Mead + Lynn Conway's book Introduction to VLSI Systems (1980) democratised IC design — universities could suddenly…
- Mechanical integratorA wheel resting on a spinning disc computes an integral without knowing it — and it took 55 years to find the force to drive…
- Mechanism, not policyThe design principle behind X11: the server supplies the tools for drawing windows but refuses to decide how they should…
- MediaMOOA text world at the MIT Media Lab where you didn't play, you attended a conference — a virtual meeting place for media…
- MediaTekTaiwanese chip designer that made cheap mobile phones possible and now ships more phone processors than anyone else.
- MedionGerman company that turned buying a computer into a discount-store event with a queue outside Aldi.
- MediumBlogging platform from a Twitter co-founder — beautiful typography, known for the paywall that annoys visitors.
- MedusaSpeculative decoding without a separate draft model: bolt a few extra heads onto the model that guess several tokens ahead…
- Meet-in-the-middle attackAn attack that makes double encryption nearly pointless by working forwards and backwards and looking for a match in the…
- MeetupPlatform for in-person gatherings around interests — programming meetups, hiking clubs, book clubs. Pre-pandemic glory days.
- MEGA65The Commodore 65 that Commodore never shipped, built thirty years later in an FPGA by enthusiasts.
- MegademoA demo in many parts with a menu in between — late 80s, when groups wanted to show off everything they could do at once.
- MegaTextureid Software's technique of clothing an entire game world in a single giant, unique texture streamed in small tiles — no more…
- MegathreadA single official thread where all discussion about a major event is channeled, to prevent the forum/subreddit from being…
- Megatron-LMNvidia's reference implementation for training large transformer models, published in 2019. The paper that introduced tensor…
- MegauploadThe Hong Kong file locker that made its money from people sharing films, until the US Justice Department switched it off in…
- MegviiBeijing company behind the Face++ facial-recognition platform, founded by Tsinghua students and, like SenseTime, blacklisted…
- MeilisearchFast open-source search engine in Rust — Algolia-like feel, but self-hosted.
- MeituanChina's dominant app for food delivery and local services, built by serial entrepreneur Wang Xing out of a Groupon clone.
- Mekka & SymposiumA German Easter demoparty from 1996 to 2002, and the first link in the chain that today is called Revision.
- Mel scaleA pitch scale based on how far apart notes sound to the ear, rather than how many hertz separate them.
- MellanoxThe Israeli company that built the fabric for supercomputers and data centres — InfiniBand and fast Ethernet — and became…
- MellotronA keyboard where every key starts its own strip of tape holding a recorded note — a sampler before the word existed.
- MelodyneA pitch editor that shows recorded vocals as blobs on a note grid and lets you drag them around with the mouse.
- MeltdownCPU vulnerability (CVE-2017-5754, Jan 2018) that let a userspace process read kernel memory via speculative execution +…
- memcachedDistributed in-memory key-value cache. Brad Fitzpatrick, 2003 (LiveJournal). Drove much of the 2000s Facebook/Twitter…
- MemeA unit of culture that spreads through copying and variation. The term was coined by Richard Dawkins in The Selfish Gene…
- Meme formatReusable image/video template where text overlay changes the meaning per use. Distracted Boyfriend, Drake Yes/No, Galaxy…
- MemexThe desk of microfilm and associative trails Vannevar Bush described in 1945, which every later hypertext system has been…
- MemoizationCache the result of a function by its input — skip recomputing on the same call.
- MemorexThe storage-media company whose ad slogan "Is it live, or is it Memorex?" is better remembered than the company itself.
- Memory controller (IMC)The circuit that handles all communication between the processor and the RAM — scheduling reads/writes, managing the memory…
- Memory fence (Memory barrier)An instruction constraining how memory operations may be moved around it. Needed because both the compiler and the processor…
- Memory leakMemory that's allocated but never released — the app grows until it crashes.
- Memory-hard functionA key derivation function that needs large amounts of RAM, so specialised hardware cannot guess passwords much more cheaply…
- MemoServThe IRC service that holds messages for users who aren't online — an answering machine for chat networks.
- MempoolThe waiting room for transactions that have been submitted but not yet included in a block.
- MEMS microphoneA condenser microphone etched into silicon, small enough that a phone can carry three or four of them.
- MemtableThe in-memory, sorted structure in an LSM tree where new writes land first before being written out to disk. When it fills…
- MentionReferences another user in a message, usually via @handle. Triggers a notification for the recipient. Standard since Twitter…
- Mention-spamAbusing @-mentions to flood someone's notifications — either as harassment (many accounts pinging a victim) or accidentally…
- Mentor GraphicsThe third of the big EDA vendors, officially Siemens EDA these days but still called Mentor by everyone who uses it.
- Menu barThe row of words along the top that drops menus when clicked — and the forty-year argument over whether it belongs at the…
- Meow WarsA Usenet war that lasted roughly two years and consisted mostly of the word "meow".
- MerakiNetwork gear you configure from a web page instead of a terminal — and which stops behaving once the licence lapses.
- MercThe big clean-up of DikuMUD's source that went on to father a large share of 1990s MUDs.
- Mercado LibreLatin America's Amazon — started in 1999 in Argentina as an eBay clone, today dominates e-commerce in 18 countries + Mercado…
- Mercedes-EuklidThe calculating machine that could divide without the operator cranking and keeping count — and did it with a drive…
- Merchant category code (MCC)The four-digit code that rides along with every card purchase and says what kind of shop the money went to.
- MercurialStarted the same month as Git, for the same reason, and was widely considered nicer to use — and lost anyway.
- Mercury (demogroup)German PC demogroup behind Fermi Paradox and the 64k intro The Timeless, both among the 2010s' best.
- Meredith PattersonLinguist and programmer, one of the originators of LangSec – the view that insecure parsers are the root of most evil.
- MERGE (SQL)SQL-standard command for upsert + delete in one. MERGE INTO target USING source ON ... WHEN MATCHED THEN UPDATE ... WHEN NOT…
- Merge conflictGit can't automatically combine two changes on the same line — you have to manually pick which one to keep.
- Merge joinJoin algorithm for already-sorted relations: iterate both at the same time (zipper merge), output matching rows. O(N+M)…
- MergesortSplit the list in half, sort each half, merge them back — O(n log n) in every case, no exceptions.
- Merkle treeHash tree where each internal node = hash of its children. Knowing only the root hash lets you verify integrity of the…
- Merkle tree (DB)A hash tree where each leaf is a hash of a data range and each node a hash of its children. It lets two replicas find…
- Merkle–Damgård constructionThe recipe for building a hash function from a compression function, block by block, with padding and a length field.
- MermaidDiagrams as text: write a few lines in a markdown-like syntax and get a flowchart.
- Mersenne Twister (MT19937)Pseudorandom number generator from 1997 by Makoto Matsumoto and Takuji Nishimura. Its period is 219937−1 — a Mersenne prime…
- MesaThe free implementation of OpenGL and Vulkan that began as a one-person software-only project in 1993 and is today the…
- mesg (Unix)The Unix command that decides whether other users may write straight into your terminal — the do-not-disturb sign of the…
- Mesh colliderA collider whose shape is an arbitrary triangle mesh instead of a primitive like a box or capsule.
- Mesh interconnectOn-chip network where CPU cores + cache slices + IO are connected in a 2D grid. Replaced the ring bus in Intel Xeon…
- Mesh shaderA modern geometry pipeline that replaces the vertex, tessellation and geometry stages with two compute-like stages that…
- Mesh simplificationReducing a mesh's polygon count while keeping its shape, to build LOD chains or lighten heavy models.
- Mesh WiFiA WiFi system with several cooperating nodes that together cover a home/office with a single seamless network. The nodes…
- MeshletA small cluster of a model's triangles and vertices — typically up to 64 vertices and 126 triangles — that the GPU treats as…
- MESIThe protocol that keeps several CPU cores' caches agreeing on who is allowed to write to a cache line. The reason shared…
- MESI protocolThe classic cache-coherence protocol, named after the four states each cache line can have: Modified, Exclusive, Shared…
- MesonModern build system — faster + cleaner than CMake. Default generator: Ninja. Python-like DSL.
- Mesosphere (D2iQ)The company that wanted to turn the whole datacenter into one computer with Apache Mesos, and lost the orchestration war to…
- Message keyThe Enigma message key was three randomly chosen letters that set up each message, sent encrypted twice.
- Message queueIntermediate layer where producers put messages and consumers pick them up — asynchronous communication.
- Message-IDThe unique label on every email and Usenet post, and the thing that kept netnews from drowning in copies of itself.
- MessageBirdAn Amsterdam messaging platform that renamed itself Bird and promised to cut prices by ninety percent.
- MessagePackBinary format that mirrors JSON's data model — Sadayuki Furuhashi, 2008. "It's like JSON. But fast and small."
- MetaThe group behind Facebook, Instagram and WhatsApp — renamed in 2021 for a bet that then gave way to AI.
- MetaballsDroplet-shaped blobs that merge and split — the sum of several invisible force fields, thresholded into a surface.
- MetabaseAn open-source tool that lets non-technical staff ask questions of a database and build dashboards without writing SQL.
- MetacityGNOME 2's window manager, deliberately built to be boring.
- Metadata"Data about data". Images: EXIF (camera, GPS, timestamp). MP3: ID3 (artist, album). Filesystem: timestamps, permissions…
- MetaFilterA community weblog from 1999 that has spent a quarter century demonstrating that a few humans moderating by hand beat any…
- MetalApple's low-level API for graphics and compute — their answer to Vulkan, and since 2018 the only route on their platforms.
- Metal particle tape (MP)Magnetic tape whose layer is made of finely divided metallic iron particles rather than oxide — higher density but more…
- Metal-evaporated tape (ME)Magnetic tape where a pure cobalt film is evaporated straight onto the base — almost nothing but magnetic material, with no…
- MetalLBGives a Service of type LoadBalancer a real external IP in clusters running on your own hardware, where there is no cloud…
- Metallic-roughnessThe PBR workflow that describes a surface with a base color, a metallic channel and a roughness channel instead of a…
- MetaprogrammingCode that generates, transforms or manipulates other code — at compile time (static) or at runtime (dynamic).
- MetaspriteA game character assembled from several hardware sprites, because one sprite alone is too small to be more than a head or a…
- MetastabilityA flip-flop whose input changed too close to the clock edge can settle into a state that is neither a one nor a zero, and…
- MetatileA block of several tiles — often 2×2 or 4×4 — treated as a single unit for storage and level design, a memory trick from the…
- MeteorThe framework where the same code ran on server and client, and database changes appeared in the browser without anyone…
- MeteoriksThe demoscene's annual awards — roughly the Oscars of real-time graphics, with noticeably fewer tuxedos.
- MetisseINRIA's experimental window system from 2004, in which X windows were rendered to memory and composited with OpenGL so…
- MetroThe JavaScript bundler for React Native, built by Meta. Originally called Packager, it serves the code to the app during…
- Metro-XMetro Link's commercial X server for Linux, bundled in Red Hat's boxed sets in the 1990s, whose module loader lives on in…
- MEX (SGI)Silicon Graphics' first window manager, sharing the IRIS workstation screen between several graphics programs before X and…
- MFA (Multi-Factor Authentication)The generalisation of 2FA — requires two or more independent proofs of who you are.
- MFA fatigue (Push bombing)The attack where someone who already has your password sends login requests over and over until you approve one — by…
- MFCC (mel-frequency cepstral coefficients)A dozen or so numbers per audio frame describing the rough shape of a sound — the workhorse of speech recognition for thirty…
- MFM (Modified Frequency Modulation)An encoding that drops the clock pulse in most bit cells and so doubles the density of the older FM scheme.
- MFM encodingDoubled a floppy's capacity by throwing out nearly all the clock transitions that FM wasted.
- MGRA small window system from Bellcore in which programs drove the graphics by writing escape sequences to their own terminal.
- MH (Message Handler)An email client that wasn't one program but a couple of dozen, one for each thing you might want to do with a message.
- Michael Ben-OrHebrew University theorist who showed that coin flips can rescue consensus and that several parties can compute together…
- Michael BurrowsComputer scientist behind BAN logic for authentication protocols – and, almost as a side project, the Burrows–Wheeler…
- Michael Calce (Mafiaboy)The fifteen-year-old from Montreal who took down Yahoo, eBay, Amazon and CNN with denial-of-service attacks in February 2000.
- Michael G. ReedOne of the three researchers at the US Navy's lab who invented onion routing.
- Michael HaydenThe Air Force general who ran both the NSA and the CIA and gave the metadata debate its most quoted line.
- Michael HowardThe Microsoft security engineer whose book landed on every Windows developer's desk when the company stopped work in 2002 to…
- Michael LubyThe theorist who proved why Feistel ciphers work, then made his money from an entirely different kind of code.
- Michael LynnThe researcher who quit his job so he could give his Cisco router talk at Black Hat 2005 — and watched twenty pages get torn…
- Michael MerrittThe Bell Labs researcher who, with Steve Bellovin, showed that a weak password can yield a strong key, as long as the…
- Michael OssmannHardware designer who made radio security something you can research on a gadget budget.
- Michael RabinThe logician who taught computer science that randomness is a tool rather than a nuisance.
- Michael ReiterAmerican security researcher who, with Avi Rubin, built Crowds, one of the first systems for anonymous web browsing.
- Michael SchroederComputer scientist whose name sits on two of security's founding texts: the Saltzer–Schroeder principles and the…
- Michael SchwarzOne of the Graz researchers behind Meltdown, who then kept finding new leaks in the same processors year after year.
- Michael StonebrakerThe database researcher behind Ingres, Postgres, Vertica, VoltDB and half a dozen more companies. Received the Turing Award…
- Michael WienerCanadian cryptographer who showed that short RSA exponents can be broken and priced out a DES-cracking machine — blueprints…
- Michał ZalewskiPolish security researcher who made coverage-guided fuzzing something anyone could run, and wrote the standard account of…
- MICKEYA 2005 stream cipher designed to need very little silicon, aimed at hardware.
- MICRMagnetic ink character recognition — the digits along a cheque's bottom edge are printed in iron-laden ink and read…
- Micro FocusBritish company that started by putting COBOL on microcomputers and ended up as a retirement home for other people's…
- Micro-op cacheA cache in the CPU's front-end that stores already-decoded micro-operations (µops), so the processor can skip the expensive…
- MicroarchitectureThe concrete internal design of a processor — how the pipeline, the caches, the execution units, and everything else is…
- Microchip TechnologyThe chipmaker behind the PIC microcontroller, which grew about as much by buying its rivals as by designing.
- MicrocodeA program inside the processor explaining to the silicon what each instruction actually means.
- Microcontroller (MCU)Mini-computer on a chip — CPU + memory + I/O in a few mm². Powers IoT devices, toys, appliances.
- Microfacet modelTreating a surface as a sea of microscopic perfect mirrors whose orientations follow a statistical distribution — the basis…
- MicroficheA flat sheet of microfilm the size of an index card, holding a grid of heavily reduced page images read in a magnifying…
- MicrokernelA kernel design where as little as possible runs privileged — drivers and filesystems move out into ordinary processes.
- MicroLED"OLED without the organics" — every pixel is a microscopic LED, not an organic diode. Promising but extremely expensive.
- MicrologicFairchild's Micrologic was the world's first commercial family of monolithic integrated circuits, launched in 1961.
- Micromusic.netAn online community for 8-bit music that, from the late 1990s, took chip music out of the demoscene and into the clubs.
- Micron TechnologyThe last American DRAM maker, started in the basement of a dentist's office in Idaho.
- Microphone preampThe first gain stage after the microphone, lifting a faint signal up to line level.
- MicropolygonA polygon diced down to roughly half a pixel, so that shading and displacement can happen per surface-covering fragment…
- MicroPro InternationalThe company that made WordStar the first best-selling word processor, then lost the whole market.
- MicroProseThe Maryland company where flight simulators and Civilization came out of the same office.
- microSDSmall flash memory card form factor (15×11mm). Standard for phones (Android), cameras, tablets, Raspberry Pi. Capacity 1GB →…
- MicrosegmentationDividing a network into very small, isolated zones — down to individual workloads/servers — and controlling the traffic…
- MicroserviceArchitecture where an application is built from many small, independent services that talk via APIs.
- MicroservicesArchitectural style: split an application into many small, independently deployable services. Each service owns its data +…
- MicrosoftComputing company founded 1975 by Bill Gates + Paul Allen. Best known for Windows + Office. Today broad: cloud (Azure), AI…
- Microsoft EdgeMicrosoft's browser — started as EdgeHTML 2015 (own engine), switched to Chromium-based in 2020. Default in Windows 10/11.
- Microsoft TeamsMicrosoft's collaboration platform — chat, video, calls, file sharing, integrated with the entire 365 stack. Launched in…
- MicroStrategyA business intelligence vendor that became a bitcoin fund with a software business on the side.
- MicrostutterSmall, irregular variation in how long each frame takes to reach the screen — the image hitches even when the average frame…
- Mid-frame palette changeWriting new colours to the palette while the beam is still drawing, so the screen shows more colours than the palette…
- Mid/sideAnother way of describing stereo: not left and right, but what the two channels share and what sets them apart.
- MIDAS Digital Audio SystemA sound library from the demogroup Sahara Surfers that played modules and effects across the motley PC sound cards of the…
- Middle-square methodVon Neumann's fast and knowingly sinful way of squeezing random numbers out of a computer.
- MiddlewareCode that runs between request and response — for authentication, logging, parsing, CORS.
- MIDIThe protocol that lets musical instruments talk to each other — and which carries no audio whatsoever.
- MIDI 2.0The first major revision of MIDI since 1983 — higher resolution, two-way conversation between devices, and full backward…
- MIDI CC (Control Change)The MIDI message for turning knobs: 128 numbered controllers per channel, each holding a value from 0 to 127.
- MIDI channelThe low four bits of a MIDI message's status byte — sixteen addresses on a single cable.
- MIDI clockA stream of 24 pulses per quarter note that keeps drum machines and sequencers at the same tempo — without ever knowing what…
- MIDI controllerAn instrument with no sound of its own: keys, pads and knobs that just send MIDI to something that can make noise.
- MIDI interfaceThe box or card that translates between a computer's buses and MIDI's five-pin DIN sockets.
- MIDI learnClick a parameter, turn a knob, and the software ties the two together without anyone needing to know which CC number the…
- MIDI Machine Control (MMC)MIDI messages for the transport buttons — play, stop, record, wind — so one machine can drive another.
- MIDI mergeCombining two or more MIDI streams into one — something a Y-cable cannot do, so it takes a small computer of its own.
- MIDI modesFour combinations of Omni on/off and Poly/Mono that decide which channels a MIDI receiver listens to and how many notes it…
- MIDI over TRSMIDI through an ordinary 3.5 mm jack instead of the five-pin DIN — sensible for small gear, and for a decade without an…
- MIDI Show Control (MSC)A MIDI extension for theatre and live events, letting lighting desks, sound systems and stage machinery share cue commands.
- MIDI ThruThe third DIN socket on classic MIDI gear, sending out an exact copy of whatever arrives at MIDI In.
- MIDI Time Code (MTC)SMPTE timecode translated into MIDI messages, so a sequencer can chase a video deck in hours and frames rather than bars and…
- MIDI Tuning Standard (MTS)A way to tell a synth exactly which frequency each MIDI note should have, rather than assuming equal temperament.
- MIDI-CICapability Inquiry: the protocol in which two MIDI devices ask each other what they can do before they start talking.
- MidjourneyImage generation service — David Holz (ex-Leap Motion), 2022. Famous for exceptional aesthetic quality and a unique…
- Midway GamesThe Chicago-area manufacturer that brought Space Invaders and Pac-Man to America, then frightened the US Senate with Mortal…
- MIG headThe ferrite head given a thin metal film right in the gap so it could write media harder than plain ferrite could touch.
- Migration (database)Versioned change to a database schema — add a table, rename a column, add an index.
- Miguel de IcazaMexican programmer who started GNOME, then Ximian and Mono, and ended up employed by the company whose technology he had…
- Mihir BellareThe cryptographer who made provable security something engineers could actually use – and a co-author of HMAC.
- Mike BondThe Cambridge researcher who showed you don't need to break an HSM to get its keys out – you just ask nicely, in the wrong…
- Mike HamburgAmerican cryptographer behind the Ed448-Goldilocks curve and Decaf, the trick that hides the awkward cofactor of Edwards…
- Mike LynnThe researcher who quit his job mid-conference in 2005 so he could explain how to take over Cisco routers.
- Mikko HyppönenFinnish malware researcher who spent over three decades at F-Secure and coined the law that anything smart is also…
- Miklós AjtaiHungarian mathematician at IBM Almaden who proved in 1996 that some lattice problems are hard on average if they are hard in…
- MikModA module player and sound library for MOD, S3M, XM and IT that quietly ended up inside countless games.
- MikroORMTypeScript ORM with Data Mapper + Unit of Work patterns (à la Hibernate, Doctrine). Martin Adámek, 2018. Czech-based…
- MikroTikLatvian networking hardware vendor. RouterOS = Linux-based proprietary OS. Aggressive pricing: enterprise features at hobby…
- MilkyTrackerA free, cross-platform music tracker built as a faithful clone of FastTracker II.
- Mill and store (Babbage)Babbage's split of the Analytical Engine into a calculating part and a holding part — the same line later drawn between the…
- Miller columnsThe file browser in which every folder you click opens a new column to the right, so the path is spelled out as a row of…
- Miller PucketteThe mathematician who wrote both Max and Pure Data, giving computer music its boxes and patch cords.
- Million.jsDrop-in optimisation for React via a compiler — "block virtual DOM" that claims 70 % faster diffs.
- MillionaireThe first calculator that genuinely multiplied instead of adding over and over — one turn of the crank per digit, with the…
- MILNETThe military half of ARPANET, split off in 1983 so that defence traffic no longer shared wires with the researchers.
- MilvusOpen source vector database for AI embeddings — index + search billions of vectors in milliseconds. Created by Zilliz 2019…
- MIME (Multipurpose Internet Mail Extensions)Standard for specifying content type in email and HTTP. Content-Type: text/html; charset=utf-8, image/png, application/json.
- MIME type (Content-Type)A label saying what kind of data a file is: text/html, application/json, image/webp.
- MimecastLondon company selling email filtering, archiving and phishing protection as a cloud service — your mail passes through them…
- MimeographA cheap duplicating machine that forced ink through a cut wax stencil — the copier of schools and clubs before the…
- MimikatzPost-exploitation tool for Windows. Extracts passwords, hashes, Kerberos tickets from the LSASS process memory. Benjamin…
- MIMOUsing multiple antennas at both ends to send several data streams simultaneously on the same frequency.
- Min-p samplingA sampling method that sets its threshold relative to the most likely token rather than absolutely. When the model is…
- MindSpringThe Atlanta ISP that printed its values on a card and actually tried to live by them.
- MindVoxA New York BBS and early internet provider, launched in 1991 by two former members of the hacker group Legion of Doom.
- MinecraftSwedish sandbox game — Markus "Notch" Persson created in 2009. Mojang sold to Microsoft in 2014 for $2.5B. Best-selling game…
- Mini-ITXA 170 × 170 mm motherboard form factor defined by VIA in 2001. The small standard that became the enthusiast favourite for…
- Mini-LEDLCD displays with thousands of small LED backlights that can be dimmed locally — closer to OLED contrast without OLED's…
- miniaudioAn audio library in C shipped as a single file: drop it in, include it, and your program plays and records on every major…
- MinicomputerThe class between mainframe and personal computer: expensive enough to be shared by a department, cheap enough not to be…
- MiniDiscSony's attempt to replace the cassette with a small magneto-optical disc in a plastic shell — beloved in Japan, overlooked…
- MinikubeLocal Kubernetes cluster for dev. Supports multiple drivers: VirtualBox, KVM, Docker, Podman, HyperKit (macOS), Hyper-V…
- MinimapThe small overview map tucked into a corner of the screen, showing the surroundings, the player and whatever is worth…
- MiniMaxA search algorithm for two-player games that picks the move that's best assuming the opponent always replies with whatever…
- MinimoogThe synth that took the modular system out of the studio and onto the stage by hard-wiring the patch cables and putting…
- Minimum phaseA filter that, for a given magnitude response, has the least possible delay — everything happens after the impulse, nothing…
- MinIOS3-compatible object storage you can run yourself — single binary written in Go. The de-facto standard for "self-hosted S3"…
- MinitelFrance's national online service that worked for thirty years — a decade before the web, with free terminals for everyone.
- MINIXA Unix-like system written as a teaching aid — and the one a Finnish student was running when he got fed up and started…
- Minkowski differenceThe set of all vector differences between two shapes; two convex shapes overlap exactly when their Minkowski difference…
- Minkowski portal refinement (MPR)A convex collision test that pushes a triangular window towards the origin of the Minkowski difference until it is clear…
- Minkowski sumThe set of all sums a+b of points from two bodies — the foundation of how modern collision algorithms reason about overlap.
- Mip biasA tunable offset that nudges which mipmap level the GPU samples — negative for sharper, aliasing-prone textures, positive…
- MipmapPrecomputed smaller versions of a texture, so distant surfaces can use an appropriately small variant rather than sampling…
- MIPSRISC CPU architecture. John Hennessy, Stanford, 1981. Acronym: "Microprocessor without Interlocked Pipeline Stages". Classic…
- MirCanonical's own display server, launched in 2013 as an alternative to Wayland for Ubuntu's phones and desktops, and since…
- Mirai botnetBotnet that hijacked IoT devices (security cameras, routers) via default passwords. Drove historically large DDoS attacks in…
- MirantisThe infrastructure company that rode the OpenStack wave, switched boards to Kubernetes, and picked up Docker's enterprise…
- mIRCThe Windows client that was IRC for an entire generation. Released in 1995 by Khaled Mardam-Bey and still under active…
- MiroOnline whiteboard for teams — rebranded from "RealtimeBoard" in 2019, exploded during pandemic-era remote work.
- MirostatA sampling method that steers the perplexity of the text with a feedback loop instead of a fixed threshold. You specify how…
- misc-fixedX's bitmap font above all others: the family from 5x7 to 10x20 that every xterm starts in, around since the 1980s, and since…
- misc.*Usenet's catch-all hierarchy for whatever fit nowhere else — buying and selling, jobs, law and raising children.
- MisskeyJapanese fediverse server software, developed by syuilo since 2014. It speaks ActivityPub and therefore federates with…
- MistigrisA computer art group founded in 1991 that still puts out art packs, long after the BBSes went dark.
- MistralFrance's Mistral AI (founded 2023 by ex-Meta/Google DeepMind researchers) — Europe's frontier challenger. Open-weights and…
- Mistral AIFrench AI startup. Founded May 2023 by Arthur Mensch (ex-DeepMind), Timothée Lacroix, Guillaume Lample (ex-Meta). Pioneered…
- MISTY1A 1997 block cipher by Mitsuru Matsui, designed to resist the linear and differential attacks of its day.
- MIT-SCREEN-SAVERThe X11R6 extension that let an external client take over the server's built-in screen saver and, more importantly for…
- MIT-SHMThe X11 extension that lets local programs hand images to the server through shared memory instead of pushing every pixel…
- MIT-SUNDRY-NONSTANDARDAn X11 extension whose only job was to put bugs back into the server so that old programs kept working.
- MiTACTaiwanese ODM group behind servers, ruggedized devices, and GPS brands like Mio and Magellan.
- Mitch KaporLotus founder who spent the fortune from a spreadsheet on starting the Electronic Frontier Foundation.
- MitelCanadian maker of business phone systems that was originally meant to sell lawnmowers.
- MITM (Man-in-the-Middle)An attack where a malicious party positions itself between client and server and can read or modify traffic.
- MITRE ATT&CKKnowledge base of how real attackers actually operate — tactics, techniques, procedures (TTPs).
- MITRE ATT&CK tacticMITRE ATT&CK is an open knowledge base of how real attackers behave, organized into tactics (WHY — the goal of a step, e.g…
- Mitsubishi ElectricJapanese industrial group whose MELSEC PLCs and CC-Link networks are standard kit on factory floors.
- Mitsuru MatsuiJapanese cryptographer who developed linear cryptanalysis and designed the MISTY1 block cipher.
- mix-blend-modeCSS property that blends an element with what lies behind it using the same modes found in image editing software…
- MixColumnsMixColumns is the AES step that mixes each column of the state through a fixed linear map over GF(28).
- Mixdown (bounce)Rendering every track, effect and automation move into a finished audio file, usually stereo.
- MixinA class/module designed to be composed into other classes — contributes functionality without being a standalone type.
- Mixing consoleThe device that takes many audio sources, shapes each one and sums them down to a handful of outputs.
- MixpanelProduct analytics that counts individual events rather than page views — who clicked what, in what order, and who came back.
- MixterGerman hacker who in 1999 wrote Tribe Flood Network (TFN) and TFN2K, among the first tools for distributed denial-of-service…
- Mixture differential cryptanalysisA technique against AES-like ciphers that builds quadruples of plaintexts by swapping column values between two pairs.
- Mixture of Agents (MoA)Together AI's 2024 method: stack multiple LLMs in layers, each refines the previous layer's output. Sometimes beats GPT-4o…
- Mixture of Experts (MoE)Neural network where only a subset of "experts" activate per token — cheaper inference at the same capacity.
- MixxxThe open-source DJ application: two or four virtual decks, a mixer, effects and support for both controllers and timecode…
- Miyaguchi–PreneelMatyas–Meyer–Oseas plus one more XOR of the previous chaining value — the variant Whirlpool picked.
- MKVMatroska — the open container format that can hold essentially anything, in any number of tracks.
- ML KitGoogle's package of ready-made machine learning features for mobile apps — text recognition, barcodes, face detection…
- ML-DSANIST's standardised digital signature for the quantum era — formerly known as CRYSTALS-Dilithium.
- ML-KEMThe quantum-safe replacement for key exchange in TLS — formerly CRYSTALS-Kyber, now FIPS 203.
- MLAGMulti-Chassis Link Aggregation — server connects to port-channel that spans TWO switches. Server sees one LACP bond…
- MLCMulti-Level Cell — NAND flash that stores 2 bits per cell via 4 voltage levels. Twice as dense as SLC, roughly half the…
- MLflowOpen source platform for tracking ML experiments — parameters, metrics, models, versions.
- MLOpsDevOps but for ML models — training, versioning, deployment, monitoring of models in production.
- MLSMessaging Layer Security — IETF standard (RFC 9420, 2023) for E2EE in large group chats. Scales to thousands of participants…
- mlvwmThe Macintosh-like Virtual Window Manager: a 1997 window manager that gave X11 System 7's striped title bars, a menu bar…
- MLXApple's open-source ML framework optimised for Apple Silicon — exploits unified memory (CPU and GPU share RAM) to avoid data…
- mmap (Memory-mapped file)Map a file directly into a process's memory — read and write as if it were a regular array.
- MMC3Nintendo's third-generation memory controller for NES cartridges, which besides bank switching counted scanlines and so gave…
- MMCSSThe Windows service that gives audio and video threads priority with the scheduler, so everything else can't crowd them out.
- MMDFThe Multichannel Memorandum Distribution Facility — the mail system that held CSNET together, including hosts reachable only…
- MME (Windows)Windows' oldest audio interface, dating from the 1991 Multimedia Extensions – still listed in every DAW's driver menu as the…
- MMLU (Massive Multitask Language Understanding)A multiple-choice benchmark spanning 57 subjects that long served as the standard measure of how "knowledgeable" a language…
- MMOGames where thousands of players share a world that goes on existing after you log out.
- MMR (Maximal Marginal Relevance)Re-ranking technique that balances relevance against diversity — avoids the top-K being near-duplicates of each other.
- MMUThe unit in the processor that translates virtual addresses into physical ones on every memory access.
- MO3 formatA tracker module whose samples are compressed with MP3 or Ogg Vorbis, shrinking a MOD to a fraction of its size.
- MobaXtermA French all-in-one terminal for Windows with a built-in X server, so a graphical Unix program over SSH simply appears with…
- Mobile firstDesigning for the smallest screen first and building upwards — not squeezing a desktop site down afterwards.
- MobileyeIsraeli firm whose EyeQ chips and camera-based vision sit behind driver assistance in hundreds of millions of cars…
- MobX"Reactive state" library — observable objects + computed values + reactions. Differs from Redux by allowing mutations (via…
- MochaJavaScript test framework. TJ Holowaychuk (same as Express), 2011. BDD syntax: describe('Foo', () => it('bar', ...))…
- MockingIn tests, replacing a real component (database, API, clock) with a fake that behaves predictably.
- MockitoJava's dominant mocking framework, created by Szczepan Faber in 2008. Replaces dependencies with stand-ins so a class can be…
- MOD formatThe Amiga's module format — samples and note patterns in one file, so the tune played on the machine instead of being…
- Mod n cryptanalysisA cousin of linear cryptanalysis that tracks how values are distributed modulo a small number rather than how individual…
- Mod wheelThe right-hand of the two wheels left of a synth's keyboard, traditionally controlling how much vibrato is added to the note.
- mod.*Early Usenet's hierarchy for moderated groups, where every post passed through a human before it reached the network.
- ModalA popup that blocks interaction with the rest of the page until closed.
- ModbusThe world's most common industrial protocol — invented in 1979 by Modicon for PLCs. Still standard on factory floors and in…
- Mode 13hVGA's simplest graphics mode: 320×200 pixels in 256 colours with one byte per pixel in a flat memory buffer.
- Mode 7The Super Nintendo graphics mode that scaled and rotated a single background layer to fake a 3D ground plane.
- Mode of operationA mode of operation decides how a block cipher is applied when the message is longer than one block.
- Mode XAn undocumented VGA tweak that switches the card into a planar 256-colour mode, usually 320×240, with access to all of video…
- ModelA trained set of weights — the actual product of ML training.
- Model cardStandardised documentation of an ML model — training data, performance, limitations, intended use, bias.
- Model soupAveraging the weights of several fine-tunes of the same base model instead of picking the best one. Often beats the winner…
- Modeline (X11)A line in the X server configuration giving the pixel clock and sync pulses for a video mode, from the era when a monitor…
- ModemMo-dulator/De-modulator — converts between digital data and the signal travelling over phone line/coax/fibre.
- Moderated newsgroupA Usenet group where posts don't go out directly but are mailed to a moderator who decides what gets published.
- modesetting (X driver)The generic X.Org driver that has no idea which graphics card it is running on, and works on nearly all of them as a result.
- Modifiers (X11)X11's eight modifier bits — Shift, Lock, Control and Mod1 through Mod5 — and the table that decides which keys set them.
- Modular arithmeticArithmetic on remainders, where numbers wrap around a modulus, and the foundation of nearly all classical and modern…
- Modular Crypt FormatThe $id$salt$hash convention that lets a password hash say which algorithm produced it.
- Modular synthesizerA synth with no fixed signal path: separate modules that the player wires together with patch cables.
- Modulation matrixA table inside a synth where each row connects a modulation source to a destination by a chosen amount, replacing fixed…
- ModuleA reusable code unit with a clear interface — what your code imports and exports.
- Module rippingPulling the music out of games and demos and making it playable on its own — part preservation, part theft.
- MoE (Mixture of Experts)Model architecture with multiple "expert" networks — only a few activate per token, so large models become cheap to run.
- MoE routingMechanism in Mixture-of-Experts: a "router" picks top-k experts per token. Top-1 (Switch Transformer), top-2 (Mixtral) most…
- Moebius (ANSI editor)A modern ANSI editor that lets several artists draw on the same canvas at once.
- Moiré effectTwo nearly identical patterns sliding across each other, breeding great shimmering bands out of pure interference — almost…
- MojangThe Stockholm studio built around a single Java hobby project, sold for $2.5 billion five years later.
- MojoChris Lattner's (LLVM, Swift) new language from Modular — aims to be Python syntax + C++ performance + MLIR/GPU support…
- Moleman 2A 2012 Hungarian documentary about the demoscene, made from the inside and free to watch online.
- MolexConnector maker whose name stuck to the power plug inside every older PC.
- Möller–TrumboreThe standard ray–triangle intersection test, which finds the hit without ever computing the triangle's plane.
- MonadFunctional abstraction for chaining computations that "carry context" — Optional, Result, Promise, List are all monads…
- monday.comBrightly coloured "Work OS" out of Tel Aviv — every workflow is built from the same bricks: boards, columns and automations…
- Monero (XMR)A cryptocurrency built so transactions cannot be traced. Launched in 2014 out of the CryptoNote protocol. Unlike Bitcoin…
- MongoDBThe best-known document database — stores BSON (binary JSON), schemaless, horizontally scalable.
- MongooseNode.js ODM (Object Document Mapper) for MongoDB. Aaron Heckmann, 2010. Adds schema validation + middleware on top of…
- Moni NaorIsraeli cryptographer who, with Cynthia Dwork, worked out that you can fight spam by making the sender do arithmetic.
- MONIACA computer of pipes, tanks and coloured water in which the money supply literally flowed through the economy and leaked out…
- Monkey patchingModify classes or modules at runtime — add methods to built-in types, swap functions in libraries, change behaviour without…
- MonoA free implementation of .NET for Linux, started by people Microsoft then regarded as the opposition — and eventually bought…
- Monoalphabetic cipherEvery plaintext letter is always replaced by the same ciphertext letter, which makes the cipher easy to break with frequency…
- MonoBehaviourThe base class behind nearly every Unity script — the thing that turns a C# class into a component on a game object.
- MonocypherSingle-file C crypto library, ~2000 LoC. Loup Vaillant. Designed for embedded systems where libsodium is too large…
- MonoGameAn open-source successor to Microsoft's discontinued XNA framework — it keeps C# game development alive, notably behind…
- MonogramA monogram is a single letter counted as a unit in cryptanalysis, as opposed to digrams and trigrams, which count letter…
- MonolithThe entire application in a single codebase and deploy unit — the opposite of microservices.
- Monolithic kernelA kernel design where drivers, filesystems and the network stack all run privileged in one address space — the Linux model.
- MonomorphizationGenerics implementation where compiler generates separate concrete-typed version per use. Vec<i32> and Vec<String> are…
- MonorepoA single Git repo containing many packages/projects — Google, Meta, Microsoft run this way.
- MonotypeAn 1887 typesetting machine that cast and set individual metal types from a punched-paper keyboard.
- MonroeOne of America's big-three desktop calculators, born from Frank Baldwin's rotary mechanism and Jay Monroe's business sense.
- Monster (VMS)A 1988 multi-user adventure in which players built the world themselves — a year before TinyMUD made the same idea famous.
- Monte Carlo methodWorking out a probability by sampling it enough times instead of solving it — invented over a game of solitaire on a sickbed…
- Monte Carlo tree search (MCTS)A search algorithm that grows a game tree through random playouts and spends its time where the payoff looks best.
- MOOThe MUD variant in which the whole world is made of objects that players can program while the server runs.
- Moog ladder filterFour transistor pairs stacked like rungs on a ladder — the low-pass filter that defined what an analogue synth is supposed…
- MoOLITUSL's 1992 toolkit that could look like OPEN LOOK or Motif depending on a resource setting, a ceasefire in the GUI wars…
- Moonshot AIBeijing AI lab behind the Kimi chatbot, founded in 2023 and known for swallowing extremely long documents in a single pass.
- Moore School LecturesEight weeks in the summer of 1946 during which the US Army paid to teach the world how to build a stored-program computer…
- Moore's lawGordon Moore's 1965 observation: the number of transistors per chip doubles roughly every two years. Driving myth of the…
- MopriaThe industry's answer to why an Android phone could not print to a printer standing three metres away.
- Mordechai GuriIsraeli researcher who has made a genre of his own out of getting data off computers that aren't connected to anything.
- Moritz LippFirst author of the Meltdown paper, and one of the Graz group that for a few years taught chipmakers to dread January.
- Morph targetAn animation technique that deforms a mesh by blending between stored snapshots of its vertex positions — the standard trick…
- Morris DworkinThe NIST mathematician whose name is on nearly every standard for how a block cipher is actually meant to be used.
- Morris wormThe first self-propagating program to knock a noticeable chunk of the internet offline, released in November 1988.
- Morton codeA way to fold multidimensional coordinates into a single number by interleaving the bits of each axis.
- MOS 6510The processor inside the Commodore 64 — a 6502 with a built-in I/O port that let the machine swap out its own memory from…
- MOS TechnologyThe small Pennsylvania chip house that sold a processor for 25 dollars and thereby made the home computer economically…
- Moses SchönfinkelShowed in 1920 that logic can dispense with variables entirely, and watched the technique get named after the man who…
- MOSFETMetal-Oxide-Semiconductor Field-Effect Transistor — the dominant transistor type in all modern digital electronics. Invented…
- Most vexing parseThe C++ rule that anything which can be parsed as a function declaration must be parsed as a function declaration — even…
- MostekTexas chipmaker that ruled the 1970s DRAM market until Japanese competition and the wrong owner finished it off.
- motd"Message of the day": the text in /etc/motd that Unix shows at every login — the notice board of the multi-user machine.
- MotherboardThe computer's main board — what everything else attaches to (CPU, RAM, GPU via PCIe, storage via SATA/NVMe).
- MotherDuckCloud DuckDB service — hybrid execution. Queries run partly on your laptop (DuckDB locally) + partly in the cloud. Founded…
- Moti YungThe cryptographer who described file-encrypting extortion malware in 1996, a couple of decades before it became an industry.
- MotifThe standard GUI toolkit of commercial Unix, remembered for its chunky bevelled edges.
- Motif clipboard (XmClipboard)Motif's own clipboard: an API with locks, formats and undo that stored data in properties on the root window rather than…
- Motif drag and dropThe first drag-and-drop protocol with real reach under X11, built into Motif 1.2 — so heavy that competitors preferred…
- Motion blurThe streak that appears when something moves during the camera's exposure — recreated so motion reads as smooth rather than…
- Motion capture (mocap)Recording a real performer's movement and mapping it onto a digital skeleton, instead of animating every pose by hand.
- Motion inputA special move triggered by a sequence of directions — the quarter-circle for a fireball, the Z-motion for an uppercut…
- Motion matchingAn animation technique that each frame searches a large database of recorded motion and plays the frame whose pose and…
- Motion path (offset-path)CSS properties that move an element along an arbitrary curve instead of straight between two points.
- Motion vectorsA per-pixel buffer recording how far each pixel moved since the previous frame, expressed in screen space.
- Motion warpingBends an animation's root motion in real time so a pre-recorded move lands on exactly the right spot in the world — a climb…
- Motion-to-photon latencyThe time from a user moving their head to the right photons actually reaching the eye on the display — VR's single most…
- MotionNotifyThe X11 event for pointer movement, complete with a built-in way of not receiving it — because a mouse can produce more…
- MotorolaMade the first mobile phone call in 1973 and the processor that drove the Macintosh, the Amiga and the Atari ST.
- Motorola 68000The processor behind the Macintosh, the Amiga and the Atari ST — and the one whose flat address space made programmers…
- MOTU (Mark of the Unicorn)The Cambridge, Massachusetts company that went from text editors to one of the Mac's first MIDI sequencers, and from there…
- MountAttaching a filesystem at a point in the directory tree — Unix's way of avoiding drive letters.
- MousePointing device for computers. Douglas Engelbart invented it in 1964, demonstrated 1968 ("Mother of All Demos"). Wooden box…
- Mouse pickingAnswering "what did the player just click on?" when the mouse only knows a pixel and the scene has three dimensions.
- Move semanticsTransferring ownership of a resource instead of copying its contents. Arrived with C++11 and is the single largest…
- Movie-plot threatA specific, cinematic attack scenario that attracts outsized defensive spending precisely because it is so easy to picture.
- Moving platformA surface that moves and is supposed to take whatever stands on it along for the ride, which makes it one of platform games'…
- Moxie MarlinspikeThe pseudonym behind Signal — and behind a billion WhatsApp users getting end-to-end encryption without asking for it.
- MozillaWhat was left when Netscape released its source code — and what broke Internet Explorer's monopoly with Firefox.
- MP-QUICMultipath QUIC — IETF draft (RFC progress 2024). Multiple network paths for one QUIC connection (WiFi + cellular…
- MP2MPEG-1 Audio Layer II — MP3's older, simpler sibling, which stayed on in radio and TV long after music libraries moved on.
- MP3Lossy compressed audio format. MPEG-1 Layer 3, standardized 1993. Karlheinz Brandenburg + Fraunhofer Institute. Created the…
- MP4The container format that works everywhere — not the most capable, but the only one you can send to anyone without thinking.
- MPE (MIDI Polyphonic Expression)An extension to MIDI that gives every single note its own pitch bend, pressure and timbre control by putting each note on a…
- MPEG-H 3D AudioAn audio codec that carries channels, sound objects and ambisonics in one stream and leaves the receiver to work out how it…
- MPLS"Multiprotocol Label Switching" — packets are forwarded by short labels instead of IP headers. Faster routing lookups and…
- MPTCP (Multipath TCP)A TCP extension that lets a single connection use multiple network paths at the same time — Wi-Fi + LTE + Ethernet.
- MPX (Multi-Pointer X)The rebuild of the X server's input layer that let several mouse pointers and keyboards coexist on one screen, each with its…
- MQA (Multi-Query Attention)A variant of attention in which all heads share a single set of keys and values while keeping their own queries. Proposed by…
- MQA (Master Quality Authenticated)An audio format that promised studio quality inside an ordinary FLAC file, and mostly demonstrated how far marketing can…
- MQA (Multi-Query Attention)Attention variant where all query heads share a single key/value pair — drastically shrinks the KV cache but sacrifices…
- MQTTLightweight pub/sub protocol for IoT — minimal overhead (2-byte header), TLS support, designed for unreliable networks with…
- MQTT-SNMQTT for Sensor Networks — a lightweight variant of MQTT adapted for very small, battery-powered devices and networks…
- MRAM (Magnetic RAM)Non-volatile RAM that stores bits as magnetic orientation in a magnetic tunnel junction (MTJ). Fast, infinite endurance…
- MRM (Motif Resource Manager)The library that loads a Motif interface from a compiled UID file at run time: the other half of UIL, and the half the…
- MS-DOSThe operating system that built Microsoft: single user, single program, command line, and 640 KB that ought to be enough for…
- MS-DOS ExecutiveThe shell of Windows 1.0 and 2.x: a file listing in a window, where you started programs by double-clicking their .EXE files.
- MS-DOS ShellThe text-based shell with menus, a file list and program groups that came with DOS 4.0 in 1988 – an admission that the…
- MSAAAnti-aliasing that takes several depth and coverage samples per pixel but runs the pixel shader only once, so only geometry…
- MSDFA way to render crisp text at any scale by storing a glyph's distance field across three colour channels instead of one.
- MsgedA free FidoNet message editor that let sysops and points read and write netmail and echomail straight from the node's…
- MsgGroupThe ARPANET's first major mailing list, started in 1975 to discuss email — by email.
- MSI (Micro-Star International)Taiwanese maker of motherboards, graphics cards and gaming laptops, recognisable by the dragon logo.
- MSN MessengerMicrosoft's instant messenger 1999–2013 (Windows Live Messenger from 2005) — Europe's dominant IM during the first half of…
- MSS clampingA router on the path rewriting the MSS value in the TCP handshake so segments are guaranteed to fit the tunnel's MTU. The…
- MSTPMultiple Spanning Tree Protocol (802.1s, 2002). Group VLANs into MST instances — each instance runs its own spanning tree…
- MSW (Mock Service Worker)Mock HTTP requests at the network layer via Service Worker (browser) or node:http interception (Node) — same code in both…
- MSXAn attempt to make the home computer a standard like VHS: the same machine from ten different manufacturers.
- Mt. GoxThe bitcoin exchange that began as a trading site for collectible cards and ended with 850,000 missing coins.
- MTBFMean Time Between Failures — a statistical measure of how long a device is expected to operate between failures. Drive…
- MTEB (Massive Text Embedding Benchmark)Hugging Face leaderboard that ranks embedding models — 56+ datasets across 8 task types (retrieval, classification…
- mTLS (Mutual TLS)TLS where both parties (client and server) present certificates — not just the server as usual.
- mTLS authenticationMutual TLS — where BOTH parties in a connection authenticate each other with certificates, not just the server (as in…
- MTM formatThe module format of MultiTracker, an early PC tracker offering up to 32 channels while the Amiga still had four.
- MTRCombination of traceroute + ping — shows packet loss and latency per hop, continuously.
- MTU (Maximum Transmission Unit)The largest packet size that can be sent over a link without fragmentation.
- MTU mismatchWhen two connected interfaces have different configured MTUs (maximum packet size). A notoriously sneaky cause of failures…
- MU-MIMO (Multi-User Multiple-Input Multiple-Output)The Wi-Fi technique that lets a router send data to several devices at the same time — instead of one at a time.
- MUDA text-based multiplayer world over telnet — direct ancestor of every MMO that later charged a subscription.
- MUD2Richard Bartle's rewrite of the original MUD, built to run as a business rather than on the university mainframe at night.
- MudflationInflation in a virtual world: when items and money keep pouring in and nothing ever leaves, everything loses value.
- MudlibThe library of game code that runs on top of a MUD driver and supplies everything that makes the game a game: rooms, combat…
- MudOSThe LPMud driver that took over from the original in the early 1990s and became the standard engine for a generation of text…
- MUI (Magic User Interface)The Amiga's object-oriented GUI toolkit from 1992, in which the program says what it wants to show and the user decides what…
- MuleSoftAn integration company named after the donkey work of getting enterprise systems to talk to each other.
- Mullvad VPNSwedish VPN service that wants to know so little about its customers it doesn't even ask for an email address.
- Multi-agent systemA system where several LLM agents with different roles collaborate to solve a task — e.g. a planner, a coder, and a…
- Multi-agent systemsMultiple LLM agents collaborating — each with its role, sharing tools and knowledge.
- Multi-Buffering (MBX)DEC's X extension from 1989 for double buffering, more buffers than two and stereo, which never became a standard but showed…
- Multi-head latent attention (MLA)An attention architecture (DeepSeek, 2024) that compresses key/value into a small latent vector instead of caching full K/V…
- Multi-key attackAttacking many keys at once and settling for whichever falls first — which gets cheaper the more targets there are.
- Multi-leaderA replication model with several "leaders" that can all accept writes and then replicate to each other. Useful for…
- Multi-masterReplication where multiple nodes accept writes at the same time. Different from primary-replica where only one node takes…
- Multi-stage buildA Dockerfile technique with several build stages where you build/compile in a heavy "build" stage and then copy only the…
- Multi-target attackGoing after many keys at once and settling for whichever one breaks first, which makes exhaustive search cheaper.
- Multiband compressionSplitting the signal into frequency bands and compressing each one separately, so a booming bass line doesn't drag the…
- MulticastSend a packet to a group of recipients — not one (unicast) or all (broadcast).
- Multicast routingDistribute one packet to multiple receivers efficiently — packet is copied at each branching point instead of one copy per…
- Multicollision attackFinding many messages with the same hash – which, for iterated hash functions, turns out to be almost as cheap as finding…
- Multicolor modeThe Commodore 64 graphics mode that halves horizontal resolution to 160×200 so each cell can show four colours instead of…
- MulticsTime-sharing OS from MIT + Bell Labs + GE 1964–2000. Ambitious, too complex, drove the creation of Unix when Bell Labs…
- MultiFinderThe 1987 add-on that let several Macintosh programs keep their windows open at once, with a cooperative multitasking model…
- MultiflowThe VLIW pioneer whose wide instruction words and trace-scheduling compiler pointed straight at Itanium — a decade too early.
- Multifunction printerAn office machine that folds printer, scanner, copier and often fax into one unit.
- MultimodalAI model that handles multiple data types — text + image, text + audio, text + video.
- Multimodal LLMAn LLM that ingests (and potentially generates) more than just text — images, audio, video. Standard in frontier models from…
- MultipaintA paint program for modern computers that deliberately imposes the colour restrictions of the old home machines.
- multipart/form-dataThe standard HTTP form for file uploads — each field separated by a "boundary" string, binary data encoded raw.
- Multiple differential cryptanalysisDifferential cryptanalysis that exploits many input and output differences at once instead of a single characteristic.
- Multiple linear cryptanalysisInstead of one linear approximation, the attacker uses many at once and adds their contributions into a stronger statistical…
- Multiple render targets (MRT)Lets a fragment shader write to several render targets at once in a single pass, each with its own contents.
- Multiplier unit (ENIAC)ENIAC's only multiplier could not actually multiply — it looked the answer up in a grid of resistors and made the…
- MultisamplingRecording an instrument at many pitches and dynamics and spreading the recordings across the keyboard, instead of…
- Multispeed (SID)C64 music whose player routine is called several times per frame instead of once, so the SID chip gets updated more often.
- MultitimbralA synth's ability to play several different sounds at once — typically bass on one MIDI channel, strings on another, drums…
- Multitrack recordingRecording instruments onto separate, synchronised tracks so they can be replaced, added to and mixed later.
- MultiXactPostgreSQL's construct for when several transactions need to lock the same row at once. It has its own counter that can wrap…
- MumbleOpen source voice chat with ultra-low latency. Since 2005. Designed for gaming — positional audio in FPS games. The server…
- MuonOptimizer from 2024 that orthogonalises the update before applying it, so every direction in a weight matrix gets roughly…
- MurataWorld's largest maker of multilayer ceramic capacitors (MLCCs) and a quietly indispensable Japanese component giant.
- Murray codeDonald Murray's 1901 reworking of the Baudot code adapted the five-bit alphabet to a keyboard and to punched paper tape.
- MuseScoreThe free scorewriter that made notation software available to everyone who didn't want to pay for Sibelius or Finale.
- MUSHThe TinyMUD offshoot where players didn't just build the rooms but programmed them, and which became the online home of…
- MUSHclientA Windows MUD client that made triggers, aliases and scripting standard kit.
- Music diskA demoscene production whose entire purpose is to play a set of tunes through a graphical front-end.
- Music information retrieval (MIR)The research field that gets computers to understand music: tempo, chords, genre, similarity and what is playing right now.
- Music SceneComposers and music programmers within the demoscene who created electronic music using tracker software or direct…
- MUSIC-NUmbrella name for Max Mathews' MUSIC I–V programs at Bell Labs (1957–1968), the common ancestor of nearly every audio…
- MusicGenMeta's 2023 music generator, which produces short instrumental pieces from a text prompt and was released with open weights.
- MusicXMLAn XML format for sheet music that lets one notation program open another's work without losing beams, accidentals and…
- muslAlternative libc implementation, focused on correctness + size + static linking. Rich Felker, 2011. Standard in Alpine…
- MustacheA deliberately logic-less template engine from 2009 by Chris Wanstrath (GitHub's founder). The name comes from {{ }} looking…
- Mustafa Al-BassamFormer LulzSec member tflow who became a blockchain-scaling researcher and co-founded Celestia.
- Mutating webhookKubernetes admission-controller extension that can MODIFY objects before they're persisted. Takes incoming YAML, returns a…
- Mutation ObserverA web API that notifies when the DOM changes — nodes added/removed, attributes changed, text updated. It gives an efficient…
- Mutation testingIntroduce deliberate bugs ("mutations") into the code and see whether the tests catch them.
- Mutex (Mutual Exclusion)Lock that ensures only one thread at a time can access a particular resource.
- MutterGNOME's window manager and compositor, its name a contraction of Metacity and Clutter.
- MutualsTwitter slang: two accounts that follow each other. "Mutuals" is short, indicates closer-than-usual-follow relationship…
- muxRob Pike's window system for the Blit's successor, the 5620: it ran inside the terminal, split the serial line into one…
- MVC (Model-View-Controller)Architectural pattern: separate data (Model), presentation (View), and the logic that ties them together (Controller).
- MVCCMulti-Version Concurrency Control — the database keeps multiple versions of the same row so readers never block writers (and…
- MVCC snapshotThe consistent "snapshot" of the database that a transaction sees under Multi-Version Concurrency Control. Each transaction…
- MVP (Model-View-Presenter)UI architecture pattern where the Presenter sits between View and Model, handles all UI logic and updates the View via an…
- MVP matrix (model-view-projection)The combined model-view-projection matrix that turns a vertex's local coordinates into screen space in a single multiply…
- MVVM (Model-View-ViewModel)UI architecture where a ViewModel exposes observable properties that the View binds to via data binding. Microsoft, for WPF…
- mwmMotif's window manager, whose bevelled grey frames defined what a commercial Unix workstation looked like around 1992.
- MXPMUD eXtension Protocol — HTML-like tags in a text stream that previously could manage colour codes and little else.
- MyISAMMySQL's original storage engine, the default until 2010. Fast, simple and entirely without transactions — which explains…
- MySpaceThe first mass-popular social network — Tom Anderson, 2003, everyone in the world's first 8 friends. Peaked as the…
- MySQLThe most-used open source relational database — the "M" in the LAMP stack.
- MySQL ABThe Swedish-Finnish company that proved open source could pay the bills — by selling the same code twice.
- Mystic BBSModern BBS software keeping the telnet scene alive on Linux, Windows and the Raspberry Pi.
- Myszkowski transpositionA columnar transposition in which repeated keyword letters share a common reading rule.
- MythicStartup that computes AI matrix multiplies as analog current inside flash-memory cells instead of digitally.
- The Mythical Man-MonthFrederick Brooks's 1975 book — still the most-cited book on software project failure. Based on IBM OS/360.
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- _NET_ACTIVE_WINDOWThe root-window property that names the active window, and the message that lets a taskbar or an application ask for it to…
- _NET_CLIENT_LISTThe root-window property where the window manager lists every window it manages, so taskbars and pagers need not guess which…
- _NET_CLOSE_WINDOWThe message a taskbar or pager sends to ask the window manager to close a window on its behalf, rather than attempting it…
- _NET_CURRENT_DESKTOPThe root-window property that says which virtual desktop is showing, and the hub of EWMH's set of workspace properties.
- _NET_DESKTOP_GEOMETRYThe root window property holding the common size of all virtual desktops: equal to the screen for most window managers…
- _NET_DESKTOP_LAYOUTThe EWMH property describing how virtual desktops are arranged relative to each other — a row, a column or a grid — so that…
- _NET_DESKTOP_NAMESThe root window property holding the names of the virtual desktops as UTF-8 strings in order, and the only one in the set…
- _NET_DESKTOP_VIEWPORTThe root window property saying which part of a desktop larger than the screen is visible right now: one coordinate pair per…
- _NET_FRAME_EXTENTSThe EWMH property that tells a program how thick a frame the window manager has put around it, so it can work out where on…
- _NET_MOVERESIZE_WINDOWThe EWMH message that lets a pager or tool ask the window manager to move and resize someone else's window, without touching…
- _NET_NUMBER_OF_DESKTOPSThe root window property holding the number of virtual desktops, set by the window manager, with an open request channel for…
- _NET_RESTACK_WINDOWThe EWMH message that lets a pager place one window above or below another, because the ordinary X route breaks once the…
- _NET_SHOWING_DESKTOPThe root window property saying whether the window manager is currently hiding every window to reveal the desktop: the mode…
- _NET_SUPPORTEDThe EWMH property on the root window where the window manager lists which parts of the spec it claims to handle.
- _NET_SUPPORTING_WM_CHECKThe handshake that lets a program decide whether an EWMH-capable window manager is actually running, without trusting…
- _NET_VIRTUAL_ROOTSThe root window property where a window manager that builds its desktops out of large child windows of the root lists them…
- _NET_WM_ALLOWED_ACTIONSThe EWMH property where the window manager lists what the user may do to a given window — move, resize, minimise, close — so…
- _NET_WM_BYPASS_COMPOSITORThe EWMH property by which a fullscreen game asks the compositor to get out of the way, so frames go straight to the screen…
- _NET_WM_DESKTOPThe EWMH property on a window that says which virtual desktop it lives on, counted from zero, or 0xFFFFFFFF for all of them.
- _NET_WM_FRAME_DRAWNThe message in which a compositing window manager tells an application that its latest frame has actually reached the screen…
- _NET_WM_FULLSCREEN_MONITORSThe EWMH addition that lets a fullscreen window span several monitors instead of just the one it happened to open on.
- _NET_WM_ICONThe property where an application leaves its icon as one or more ARGB images of any size, instead of the monochrome bitmaps…
- _NET_WM_ICON_GEOMETRYThe property where a taskbar records where a window's button sits, so the window manager knows where to shrink the window to…
- _NET_WM_MOVERESIZEThe message an application sends when the user has started dragging something the application drew itself — a title bar or a…
- _NET_WM_OPAQUE_REGIONThe EWMH property by which a window with an alpha channel declares which rectangles are actually solid, so the compositor…
- _NET_WM_PIDThe EWMH property where a program writes its own process ID on the window, so the window manager can kill the right process…
- _NET_WM_PINGThe window manager's way of finding out whether an application has hung, and the PID property that then makes it possible to…
- _NET_WM_STATEThe EWMH property that lists a window's states, from maximised and fullscreen to "always on top", and the way a program asks…
- _NET_WM_STRUTThe EWMH property that lets a panel reserve one edge of the screen, so maximised windows stop above the taskbar instead of…
- _NET_WM_USER_TIMEThe EWMH property where a program stamps its window with the time of the user's last keypress or click, so the window…
- _NET_WM_WINDOW_OPACITYThe property that makes an entire window translucent in the compositor, never adopted by any specification yet supported by…
- _NET_WM_WINDOW_TYPEThe EWMH property through which a program declares what kind of window it is opening, so the window manager can treat a…
- _NET_WORKAREAThe root window property holding the part of the screen not covered by panels: x, y, width and height per desktop, computed…
- .newsrcThe text file in your home directory where a Usenet reader remembered which groups you subscribed to and which articles you…
- Linux namespaceKernel mechanism that gives processes an isolated view of system resources. Container = process + namespaces + cgroup. Seven…
- N-gramA run of n adjacent characters or words, used to measure how language-like a text is.
- N+1 query problemThe most common performance bug in ORM use: one query for the list + N queries for each row's relations.
- n8nSelf-hostable Zapier competitor — visual node-based workflow editor, write your own nodes in TypeScript. docker run and go.
- NACL (Network ACL)Stateless firewall at the subnet level in AWS — allow AND deny rules, numbered priorities. Complement to stateful Security…
- Nadhem AlFardanThe researcher who, while still a PhD student, helped knock out both cipher options TLS had left in 2013.
- Nadia HeningerCryptographer who documents how real-world cryptography breaks — not on paper, but across millions of misconfigured devices…
- Nagle's algorithmJohn Nagle 1984 (RFC 896) — buffers small writes instead of sending 1-byte packets. Saves network but increases latency.
- NamcoThe Tokyo firm that started with rooftop kiddie rides and ended up giving the world Pac-Man.
- Name manglingThe compiler encoding an entire signature — namespace, class, parameter types, qualifiers — into a single symbol name…
- NamecheapThe domain registrar that grew by not being GoDaddy.
- NamespaceLogical grouping that isolates things with the same name — exists in Kubernetes, Linux, programming languages.
- Namespaces (Linux)The Linux kernel's mechanism for giving a group of processes their own isolated view of the system — their own process IDs…
- NametableThe NES background is a grid of tile numbers stored here, each byte pointing into the pattern table for the actual pixels.
- Naming conventionsStandardised way of naming variables/functions/classes — depends on language and project.
- NaN (Not a Number)Special floating-point value representing "not a number" — result of 0/0, sqrt(-1), parseFloat("abc").
- NaN boxingStuffing pointers, integers and type tags into the bits a floating point number does not use when it represents a…
- NaniteUnreal Engine 5's system for rendering film-quality meshes with billions of triangles and no hand-authored levels of detail.
- NannyMUDLinköping's LPMud, started in 1990 by the Lysator computer club and one of the oldest MUDs still running.
- nano (GNU nano)The terminal editor for when you just want to change one line in a config file. Started in 1999 by Chris Allegretta as a…
- Nano-X (Microwindows)The tiny window system for embedded Linux that draws straight into the framebuffer and offers two APIs at once, one that…
- NanoloopOliver Wittchow's synth-and-sequencer cartridge that turned a Game Boy into a pocket drum machine.
- nanomsgPieter Hintjens' "ZeroMQ done right" — simpler API, no native pub/sub topic filtering, BSD-licensed instead of LGPL. Mostly…
- Nanostores~250-byte state library — framework-agnostic, works with React, Vue, Svelte, Solid, Lit. Default state solution for Astro…
- NAPIThe mechanism that makes a Linux network driver stop using interrupts and start polling once traffic gets dense enough. The…
- Napier's bonesThe multiplication table sawn into ivory rods, so that a large multiplication becomes a matter of adding digits diagonally.
- NapsterThe 1999 file-sharing service that let millions of students download each other's music, and that the record industry then…
- Narrow phaseThe second collision stage, deciding exactly whether two already-shortlisted objects really touch, and how.
- NAS (Network-Attached Storage)File server for the home or office — multiple disks with RAID, accessed via SMB/NFS.
- NAT (Network Address Translation)The trick that lets 10 home devices share a single IPv4 address to the internet.
- NAT Gateway (cloud NAT)Managed NAT service in the cloud — lets private-subnet resources reach the internet outbound but blocks inbound. AWS NAT…
- NAT hairpinningWhen an internal client reaches another internal server via the router's public IP — the traffic must "turn in the hairpin"…
- NAT traversalTechniques to establish P2P connections through NAT — STUN, TURN, ICE, hole punching.
- NAT64 (with DNS64)The technique that lets an IPv6-only client reach servers that only have IPv4. Necessary for a pure IPv6 network to be…
- Natalie SilvanovichThe researcher who mapped what messaging apps do with incoming data before you've even noticed it arrived.
- Nate LawsonThe security consultant who helped design Blu-ray's copy protection, found timing leaks in other people's crypto libraries…
- National InstrumentsThe Texas company that turned the PC into a lab instrument and let engineers program by drawing wires between boxes on…
- National SemiconductorAmerican chipmaker that became the heavyweight of analog electronics after poaching a large slice of Fairchild's leadership.
- Native InstrumentsThe Berlin company that made software instruments a serious alternative to hardware, with Reaktor, Kontakt and Traktor.
- Native VLANThe VLAN on an 802.1Q trunk whose traffic is sent untagged. Everything else is marked with a VLAN tag; the native VLAN goes…
- NativeScriptCross-platform mobile framework — build native iOS/Android apps with JavaScript/TypeScript. Telerik (then Progress), 2014…
- NATSHigh-performance messaging for cloud-native — Derek Collison (ex-TIBCO, Cloud Foundry), 2010. Subject-based pub-sub, low…
- NATS JetStreamPersistence layer on top of NATS messaging — adds at-least-once delivery, replay, key-value store, object store. Released…
- NaturalMotionA British company that started out simulating nervous systems at Oxford and ended up making mobile games about cars and…
- Naughty DogSony's flagship studio, which went from Crash Bandicoot to The Last of Us without ever losing its focus on storytelling.
- Nautical AlmanacA British sea almanac run for 160 years as a calculation factory staffed by home workers, and the first scientific…
- NautilusGNOME's file manager since 2001, written by a dot-com that went under two months after version 1.0.
- Navajo code talkersUS Marines who ran WWII radio traffic in a code layered on top of the Navajo language — one the Japanese never broke.
- NaverSouth Korea's dominant search portal, and one of the few markets Google never conquered.
- Navigation APIThe successor to the History API, built so single-page applications can handle navigation without the ugly tricks that have…
- Navigation gridThe world is divided into a grid of free and blocked cells that is searched with A*.
- NavmeshA simplified polygon map of where in the game world a character can actually walk.
- Navmesh carvingCutting a hole in the navigation mesh at runtime wherever a moving obstacle sits, so pathfinding routes around it instead of…
- NB-IoTNarrowband IoT — a 3GPP standard (Release 13, 2016) for low-power IoT over licensed cellular spectrum. An operator-run…
- NCD (Network Computing Devices)The company that turned the X terminal into a product category in 1988 and sold more of them than anyone else, until the PC…
- NCP (Network Control Program)ARPANET's first host-to-host protocol, which let machines on the network open connections to each other until TCP/IP…
- NCRThe cash register company from Dayton that taught Thomas Watson how to sell, broke Enigma for the US Navy and scanned the…
- NCR paperCarbonless copy paper that transfers writing without a sheet of carbon paper in between, thanks to microencapsulated dye.
- NCSA TelnetThe Telnet client from an Illinois supercomputing centre that gave Macs and PCs their own way onto the internet.
- NDJSON / JSON Lines"Newline-delimited JSON" — one JSON record per line. Streamable, appendable, partitionable. Not an official standard but a…
- NDP protocolRFC 4861. Full protocol handling IPv6 link-layer discovery: neighbor discovery, router discovery, parameter discovery…
- Neal KoblitzAmerican number theorist who in 1985, independently of Victor Miller, proposed building cryptography on elliptic curves.
- Near letter qualityA dot-matrix print mode that ran the head over each line more than once to fill the gaps between dots and approach the even…
- Nearest-neighbor filteringTexture filtering that simply takes the closest texel with no blending — the thing that gives pixel art crisp edges instead…
- NECJapanese telecom and computer maker that for about a decade simply was the Japanese personal computer.
- NecropostingReplying in a thread that has been dead for seven years — irritating on a forum, invaluable on Stack Overflow.
- Nectarine Demoscene RadioA web radio station where listeners fill the queue themselves, and almost everything played comes out of the demoscene.
- Neel MehtaThe Google researcher who found Heartbleed and then would rather not talk about it.
- Negative edgeAn input quirk where releasing a button counts the same as pressing it, so a special move can fire on the release instead of…
- Negligible functionCryptography's formal way of saying "too small to matter": eventually smaller than one over every polynomial.
- Neighbor Discovery (NDP, IPv6)IPv6's replacement for ARP — uses ICMPv6 (types 133-137) instead of broadcast. Multicast to "solicited-node" addresses.
- Neo4jThe best-known graph database — nodes + relationships, query language Cypher. Swedish-founded.
- NeonServerless Postgres — separated storage and compute, scale-to-zero, instant branching like git ("copy the prod database for…
- NeonodeA Swedish company that sold a swipe-driven touchscreen phone three years before the iPhone, went bankrupt, and survived as a…
- NeovimVim fork from 2014 that modernised the codebase — Lua as the primary scripting language, async-driven, built-in LSP (since…
- NESThe console that revived a dead market — by controlling exactly who was allowed to release games for it.
- NESSIEThe European project that set out to recommend cryptographic algorithms alongside AES.
- Nest LabsThe company that made the thermostat something people wanted to show off, and which Google bought for $3.2 billion.
- Nested loop joinSimplest join algorithm: for every row in the outer relation, scan the inner relation and output matches. O(N×M) in general…
- Nested setA tree model where each node gets two numbers — a left and a right value — assigned by "walking around" the tree. A subtree…
- Nested transactionTransaction within transaction. Standardized in SQL but sparse support in RDBMS. PostgreSQL/MySQL emulate via savepoints…
- NestJSOpinionated Node.js framework. Kamil Myśliwiec, 2017. Inspired by Angular: decorated classes, dependency injection, modules…
- net.*Usenet's original flat namespace: for most of the 1980s, every newsgroup of general interest was called net.something.
- net.godA half-ironic title for the Usenet veterans whose word carried more weight than everyone else's, often because they ran the…
- NetAppThe storage company that sold a file server incapable of anything else, and made that a selling point.
- netcat (nc)"The TCP/IP Swiss army knife" — reads and writes arbitrary data across network connections. The original was released…
- NetcodeThe umbrella term for how a multiplayer game keeps every client agreeing on one world despite light being too slow.
- NetcomThe San Jose provider that turned the shell account into a mass-market product and was, for a while, the largest ISP in the…
- NetcraftA British company from Bath that has counted web servers every month since 1995, which made it the referee everyone quoted…
- NetEaseChina's second-largest game company, which began as an email portal and accidentally built an empire of online games, music…
- netem (Network Emulator)The Linux kernel's built-in tool for making the network deliberately worse. It adds delay, packet loss, jitter, reordering…
- NetezzaThe database that wedged a circuit between the disk and the CPU so it wouldn't move data it didn't need.
- NetfindA people search engine that tracked down email addresses by detective work across DNS, finger and SMTP.
- NetflixStarted with DVDs in the post, and on the way to streaming became one of the most influential voices in operations and…
- NetFlowCisco protocol for exporting traffic flow data from routers — who talked to whom, how much, on which ports. The standard for…
- NetgearCalifornian maker of routers and switches for homes and small offices, these days leaning on expensive models with lots of…
- NetiquetteThe unwritten social rules of the internet, formalized in 1995 as RFC 1855 — one of very few IETF documents that is about…
- NetizenA citizen of the net: someone who doesn't just use it but takes responsibility for it — a notion Michael Hauben popularised…
- NetlabelA record label that exists only online and usually gives its music away.
- NetlibA repository of numerical software, started in 1985, that mailed source code to anyone who put the right command in an email.
- NetlifyJAMstack pioneer — popularised "git push deploy" for static sites. Today full-stack with edge functions, forms, identity.
- NetLogoAn agent-based modelling environment where you describe how one individual behaves and then watch what a thousand of them do…
- NetmailFidoNet's private person-to-person mail, routed node to node until it reached the recipient — the network's original and…
- NetMDSony's 2001 USB bridge that let a PC pour music onto a MiniDisc recorder at high speed — but only pour it on.
- NetnodA foundation-owned Swedish company running a large share of the country's internet plumbing — the kind nobody thinks about…
- NetNorthCanada's branch of BITNET — the academic network that gave the country's universities email and mailing lists before the…
- NetrekA 16-player space strategy game generally counted as the internet's first team game — and still being played.
- NetscapeThe browser that made the web a mass market, and whose 1995 IPO started the dotcom era.
- NetScoutAmerican company selling packet capture and network monitoring to carriers and enterprises, and since 2015 DDoS protection…
- NetskopeA company built on one awkward question: which cloud services are employees actually uploading the company's files to?
- NetsplitWhen two servers in an IRC network lose contact with each other and the network splits into two halves, each of which…
- NetSuiteThe first cloud-based business system — started with Larry Ellison's money and eventually absorbed by his Oracle.
- NettyJava NIO-based asynchronous networking framework. Trustin Lee, JBoss 2004. The heart of nearly every high-performance Java…
- Network AssociatesThe name McAfee went by for seven years after merging with Network General, and under which it bought both PGP and Dr…
- Network namespaceLinux isolation where a process group gets its own network stack: own interfaces, IP addresses, routing tables, iptables…
- Network policy (K8s)A Kubernetes firewall rule that controls which network traffic is allowed to and from pods. By default, all pods can talk to…
- Network slicing5G SA feature: carrier carves a dedicated-bandwidth virtual-network ("slice") for a specific customer. Each slice has…
- Network SolutionsA small Virginia contractor that got exclusive control of .com at the exact moment everyone wanted one.
- Network transparencyThe property of X11 that a program and the screen it draws on can sit on different machines, without the program noticing…
- NetZeroFree dial-up internet provider from 1998 that traded an ad banner for a connection — you surfed for nothing as long as you…
- Neural Amp ModelerSteven Atkinson's open-source project for training a neural network on a real guitar amp, and the thing that made amp…
- Neural audio codecAudio compression in which a trained encoder and decoder replace the hand-built psychoacoustic models of MP3 and Opus.
- Neural networkA mathematical structure loosely inspired by the brain's neurons — multiple layers of nodes passing information along and…
- New Note Action (NNA)Impulse Tracker's rule for what happens to a note that is still sounding when the next one lands on the same channel.
- New RelicSaaS observability — Lew Cirne, 2008 (an anagram of his own name). One of the first APM pioneers for Java/Ruby applications.
- New user votingA BBS feature, usually called NUV, in which existing members voted yes or no on whether a new applicant got in.
- NewbieUsenet's word for the newcomer who hadn't read the FAQ yet — affectionate or contemptuous, depending on how the question was…
- NewgroundsThe portal where a generation published its first Flash animations and games. Started by Tom Fulp in 1995 and still running.
- NewlineThe character that ends a line of text — \n, ASCII 10, historically called line feed.
- NewmanryThe section at Bletchley Park told to break the Lorenz cipher with machines instead of people — and which therefore ended up…
- NeWSSun's 1986 window system, in which clients sent PostScript programs to the server instead of finished drawing calls.
- News spoolThe directory where a Usenet server kept every article — traditionally one file per article and one directory per group.
- news.*Usenet's hierarchy about Usenet itself — groups for new users, administrators, newsgroup proposals and the collected FAQs of…
- news.admin.net-abuseThe Usenet hierarchy where the net's early anti-spam movement organised itself, counted spam and handed down sentences.
- Newsfeed (Usenet)The arrangement between two Usenet servers about which groups they pass to each other — the thing that held together a…
- NewskoolThe bright, high-resolution ASCII style that emerged in the late 1990s as a deliberate reaction against oldskool.
- NewsletterPublishing over email. The most old-fashioned channel there is, and simultaneously the one enjoying a renaissance, for…
- NewsWatcherThe Mac's Usenet reader of the early 1990s: free, graphical, and written by the same person who wrote the Disinfectant…
- Newton DynamicsJulio Jerez's physics engine, which chose accuracy over speed at a time when everyone else was doing the opposite.
- newtype patternWrap an existing type in a new distinct type with no runtime overhead — so the compiler can distinguish UserId(u64) from…
- NexGenA Californian CPU start-up whose x86 core translated instructions into RISC-like micro-ops – and which ended up saving AMD.
- NexonA South Korean games company that was early to graphical online games and all but invented free-to-play with paid items.
- NeXTThe company Steve Jobs started after being pushed out of Apple, which ended with Apple buying both the company and him.
- Next.jsReact's most popular meta-framework — Vercel, 2016. SSR, SSG, ISR, edge rendering, file-based routing, server actions, all…
- NextdoorSocial network bounded by your physical neighbourhood — lost cats, parking complaints, "are these fireworks or gunshots?".
- NextivaWeb-hosting money turned into a business phone system in the Arizona desert.
- NeXTSTEPThe operating system Steve Jobs built in exile — the first web browser was written on it, and it became the foundation of…
- NFC (Near Field Communication)Short-range wireless communication (< 4 cm) — contactless payment, card reading, "tap to pair".
- NFO fileThe text file with an ASCII logo and release details that ships with every scene release — receipt, billboard and artwork in…
- NFO viewerA program that displays NFO files with the right character set, so the release group's ASCII logo doesn't turn into alphabet…
- NFS (Network File System)Classic way to mount a remote filesystem as if it were local — Sun, 1984.
- NFTA token that is unique rather than interchangeable — a record of ownership on-chain, usually pointing at something stored…
- nftablesModern Linux packet filter, successor to iptables. Faster, atomic rule updates, one core instead of…
- nginxModern web server and reverse proxy — faster than Apache at many concurrent connections.
- ngrokGives your local development server a public HTTPS address. Run ngrok http 3000 and you have a URL that works from outside…
- NianticThe Google side project that got millions of people out of the house to catch Pikachu in a car park.
- NibblerA disk copier that duplicates a floppy at the raw GCR level, letting it clone copy-protected disks that ordinary sector…
- NIC (Network Interface Card)The hardware connecting a machine to the network, and the holder of its MAC address.
- Nice valueA process's politeness number — how willing it is to give up CPU time. It runs from −20 to 19.
- Nicholas CarliniThe security researcher who has made a speciality of breaking published defences for machine learning models, often within…
- Nicholas JacobsenAmerican hacker who spent the better part of a year inside T-Mobile's customer database — including a Secret Service agent's…
- Nicholas WeaverICSI researcher who calculated how quickly a worm could take over the internet — and then watched Slammer do it.
- Nick collisionWhat happens when two IRC users with the same nickname meet after a netsplit and the network has to decide who keeps it.
- Nick MathewsonTor co-founder and, for two decades, the author of much of the code that actually runs the network.
- Nick SullivanThe cryptographer who built much of Cloudflare's TLS machinery and carried it into the IETF.
- Nick SzaboComputer scientist and lawyer who coined the term smart contract and sketched Bit gold, one of Bitcoin's closest ancestors.
- NickServThe service bot that owns the nickname registry on an IRC network. Its companion ChanServ does the same for channels…
- Nicolas CourtoisFrench cryptanalyst at University College London, best known for claiming in 2002 that AES could be solved as a system of…
- Nicolas FalliereFrench malware analyst at Symantec who worked out what Stuxnet actually did to the industrial controllers it went looking…
- Nicole PerlrothFormer New York Times security reporter who wrote the book on the global trade in zero-days.
- Niels FergusonDutch cryptographer from the Schneier circle who in 2007 pointed out where an NSA backdoor in Dual_EC_DRBG could live — six…
- Niels ProvosGerman security researcher who gave the world bcrypt, privilege separation in OpenSSH and honeyd.
- Nigel SmartBritish cryptographer who broke a whole class of elliptic curves in linear time, then made secure multiparty computation…
- Nihilist cipherA Polybius square plus a keyword, added as ordinary numbers – the choice of Russian revolutionaries in the 1880s.
- Nikita BorisovCryptographer who helped sink WEP and then built the OTR messaging protocol.
- Niklaus WirthThe Swiss designer of a series of languages built on one stubborn principle: better small and comprehensible than large and…
- NimA statically typed systems language with Python-like indentation syntax. Started by Andreas Rumpf in 2008 (originally called…
- NimatronA ton of relays built in 1940 to play one single game against fairgoers — and win nine times out of ten.
- Nimble StorageThe storage company whose cloud-based InfoSight analytics made "call support" nearly obsolete — bought by HPE in 2017.
- Nine-slice scalingScaling a 2D image by dividing it into nine regions, where the corners keep their size while the edges and centre stretch…
- NinjaMinimal build system designed for speed — Evan Martin at Google, 2010, originally for Chromium. Replaces Make when builds…
- NINJAMInternet jamming software that gives up fighting latency and instead delays everything by exactly one musical phrase.
- NintendoFounded in 1889 to make playing cards — and still in Kyoto, having tried taxis, love hotels and instant rice along the way.
- NIO (Java New I/O)Java's non-blocking I/O API, introduced in Java 1.4 (2002). Three concepts: channels, buffers and selectors. The foundation…
- Nir ZukFounder of Palo Alto Networks, whose firewall looked at the application instead of the port number.
- NIS2The EU's cybersecurity directive (2023) — extends NIS1 to more sectors and stricter requirements.
- NISQThe label for today's quantum computers — enough qubits to be beyond simulation, too noisy to be useful.
- NIST SP 800-108NIST's recommendation for deriving several keys from one secret using a pseudorandom function such as HMAC or CMAC.
- NIST SP 800-132NIST's 2010 recommendation for deriving encryption keys from passwords, effectively a user manual for PBKDF2.
- NIST SP 800-38AThe US standard that first specified the five block cipher modes, published in 2001.
- NIST SP 800-38DNIST's 2007 standard specifying GCM and its authentication-only sibling GMAC.
- NIST SP 800-38FNIST's 2012 recommendation for encrypting keys under other keys: KW, KWP and TKW.
- NIST SP 800-56CNIST's standard for turning the shared secret from a key exchange into actual keys.
- NIST SP 800-57NIST's recommendation for key management – the document that decides how long a key may live and how long it needs to be.
- Nits (cd/m²)The unit for display brightness — candela per square metre. 1 nit = 1 cd/m².
- NixA package manager built on the idea that an installation is a pure function of its inputs. Came out of Eelco Dolstra's…
- Nix & NixOSFunctional package manager where every package is stored in a unique hash-based path (/nix/store/abc...-postgres-16)…
- Nix FlakeReproducible-by-default Nix project format. flake.nix + flake.lock pin all deps exactly. Stable since Nix 2.4 (2021)…
- Nixdorf ComputerWest Germany's big computing success story, built on compact office machines from Paderborn and absorbed by Siemens after…
- NJEIBM's protocol for moving jobs, print output and files between mainframes — and the thing BITNET actually spoke.
- NKS (Native Kontrol Standard)Native Instruments' format for making third-party plugins behave as if they were NI's own on Komplete Kontrol and Maschine…
- nl.*The Dutch Usenet hierarchy, in the country that happened to host Europe's hub.
- NLFSR (nonlinear feedback shift register)A shift register whose feedback is a nonlinear function, which is why the classic Berlekamp–Massey attack does not get you…
- NLP (Natural Language Processing)The AI field that handles human language — translation, summarisation, classification, speech recognition.
- NmapThe classic port scanner — maps networks, finds open ports, fingerprints services.
- nn (newsreader)"No News is good news" — the Usenet reader that had you pick what was worth reading before you started reading.
- NNTPThe protocol that moved Usenet off dial-up UUCP batches and onto live TCP connections between news servers and readers.
- NO CARRIERThe modem's way of saying the carrier is gone and the call is over — and, for a generation of BBS users, a way of saying…
- No Silver BulletFrederick Brooks's 1986 essay: "There is no single technical tool that yields a 10× productivity gain in software…
- No-cloning theoremAn unknown quantum state cannot be copied. Proved in 1982, and the consequences run through the entire field.
- No-IntroA preservation group cataloguing clean, unmodified game ROMs – the name is a promise that no cracker has bolted an intro…
- NoCeMUsenet's answer to the cancel-message problem: signed lists of posts to hide, where each reader decides whose judgement to…
- NoclipThe mode where the player's collision is switched off, so the camera glides freely through walls, floors and out into the…
- NoctuaAustrian PC-fan maker — beige/brown colour scheme, premium pricing, worshipped by enthusiasts for silence and quality.
- NodeGeneric term for an element in a data structure or network. Concrete meaning depends on context: tree node, graph node…
- Node affinityKubernetes feature: control which nodes a pod is scheduled on based on node labels…
- Node Problem DetectorA daemonset that reads the kernel log and systemd status on every node and translates what it finds into Kubernetes node…
- Node.js (node-js)JavaScript runtime built on V8 + libuv. Lifted JS from browser to server-side in 2009. Ryan Dahl created it, the OpenJS…
- NodelistFidoNet's phone book — a weekly master list of every node on the network, with its address, sysop name, and dial-up number.
- Noise floorThe noise that is still there when nothing is playing — the level below which anything quieter simply disappears.
- Noise gateA dynamics processor that shuts the signal off when it drops below a threshold — silence becomes actual silence instead of…
- Noise ProtocolCryptographic protocol framework from Trevor Perrin (also Signal Protocol co-author), 2016. Builds handshakes from DH +…
- Noise shapingPushing quantisation noise into the frequencies the ear cares least about, so fewer bits sound like more.
- NoiseTrackerAmiga tracker from 1989 that cleaned up the Ultimate Soundtracker and became the bridge to ProTracker.
- NokiaA Finnish pulp mill that became the world's biggest phone maker, missed the smartphone, and survived by selling the networks…
- NomadHashiCorp's container orchestrator — a minimal alternative to Kubernetes.
- NomenclatorA hybrid of substitution alphabet and codebook that ran European diplomacy for four centuries.
- NomogramA drawing that calculates: lay a straightedge across two known values and read the answer where it crosses the third scale.
- Non-repudiationSecurity property: the sender cannot later deny they sent the message.
- Nonce (Number Used Once)A random number or counter used only once — prevents replay attacks.
- Nonce misuse resistanceThe property that an encryption scheme stays reasonably secure even when the same nonce is used twice.
- Nonce reuseReusing a nonce with the same key is one of the quickest ways to break a stream cipher or a GCM construction.
- Nonlinear invariant attackA generalisation of the invariant subspace attack in which the preserved pattern is a nonlinear Boolean function rather than…
- NonStopTandem's fault-tolerant system from 1976 that banks and exchanges still trust for transactions that must not die.
- NonsystemAmiga software that switches the operating system off and drives the hardware directly — fast, efficient, and with no way…
- Norbert WienerThe child prodigy who gave the science of feedback a name: cybernetics.
- Norden bombsightAn analog fire-control computer that flew the aircraft during the bomb run, cost nearly as much as a nuclear weapons…
- Nordic SemiconductorThe Norwegian fabless firm that came to dominate Bluetooth Low Energy with its nRF chips.
- NORDUnetThe shared backbone of the Nordic research networks, and the reason the Nordics got onto the internet early.
- NordVPNThe consumer VPN with Lithuanian roots that is better known for its YouTube sponsorships than for its protocols.
- Normal mappingA texture whose RGB values encode surface normals, so a flat surface catches light as if it were detailed — with no extra…
- NormalizationDesign principle for relational databases — no redundant data, everything in its place.
- Normalized device coordinates (NDC)The cube-shaped coordinate space after the perspective divide, where everything visible lives in a range around zero…
- Norman Joseph WoodlandThe man who dragged four fingers through the sand on Miami Beach and thereby invented the idea of encoding digits as bars of…
- Norsk DataNorwegian minicomputer maker that was briefly one of the heaviest stocks on the Oslo exchange in the 1980s, and then very…
- NortelCanada's telecom giant, which in 2000 made up roughly a third of the Toronto Stock Exchange's value and nine years later was…
- North Star ComputersA Berkeley outfit whose Horizon and idiosyncratic hard-sectored floppies were standard kit in early S-100 systems.
- Norton DesktopSymantec's replacement for the Windows 3.x shell, with icons on the desktop, a trash can and drag and drop, four years…
- NoSQLUmbrella term for databases that aren't classically relational — document, key-value, graph, columnar.
- NostrNotes and Other Stuff Transmitted by Relays — a decentralized social protocol based on cryptographic keys instead of…
- Nostr relayA server in the Nostr network that stores and forwards signed posts. A user publishes to several relays at once; clients…
- NotarizationApple's process where a finished app is submitted for automated scanning before it may be distributed outside the App Store…
- NotchThe cutout at the top of the screen housing the front camera and sensors — introduced with the iPhone X in 2017 and then…
- Notch filterA filter that removes a very narrow band of frequencies and leaves everything else nearly untouched.
- Note diskA floppy full of personal messages and greetings that swappers mailed around — the scene's social feed before the net…
- Note Expression (VST 3)Steinberg's way of giving each individual note in a chord its own pitch, volume and timbre, independent of the others.
- Note GThe last and longest of Ada Lovelace's seven 1843 notes, containing a table that computes Bernoulli numbers — usually called…
- Note On / Note OffMIDI's two basic messages: a key went down, a key came up — and all the trouble that follows when the second one never…
- Noter (demoscene)A small program that displays a scrolling text note — the home-computer scene's way of sending greetings, swap lists and…
- Notes (Instagram)A lightweight status feature on Instagram where you post a short text note (max ~60 characters) that appears above the DM…
- NotesfilesThe University of Illinois discussion system that brought PLATO's conferencing culture to Unix and lived alongside Usenet…
- Nothing-up-my-sleeve numbersConstants chosen in a way anyone can check, so nobody can claim they hide a backdoor.
- Notion"All-in-one" workspace — notes, wikis, databases, kanban, docs in the same block-based editor.
- Notion AIAI features built into Notion — "write a summary", "improve this text", Q&A over the whole workspace via RAG.
- NotPetyaJune 2017 — Russian GRU disguised wiper as ransomware. Spread via Ukrainian accounting software M.E.Doc supply-chain attack…
- NOV (News Overview)A per-group summary database that let newsreaders build threads without opening every single article.
- NovellThe Provo, Utah company whose NetWare was what office networks of the eighties and nineties actually ran on – until Windows…
- NovuOpen-source notification infrastructure that puts email, SMS, push and in-app notifications behind one API and one workflow.
- npmNode Package Manager — world's largest package registry with 3M+ packages. Isaac Schlueter, 2010. Default package manager…
- NPU (Neural Processing Unit)Dedicated AI accelerator on a chip — for on-device ML without draining the battery or burdening the CPU/GPU.
- NRENNational Research and Education Network — Al Gore's planned gigabit network for science, and today the generic name for…
- NRPNNon-Registered Parameter Number — MIDI's way of addressing more parameters than 128 controller numbers allow, by spreading…
- NRZI encodingEncodes a one as a transition and a zero as no transition — making flux changes, not voltage levels, the carrier of data.
- NsCDENot so Common Desktop Environment: a reconstruction of CDE's look and workflow built on FVWM, with front panel, workspaces…
- NSF formatA file format that ships the NES's own playback code instead of finished audio, so a player runs the code and regenerates…
- NSFNETThe US research backbone that took over from ARPANET and then handed the internet to commercial carriers.
- nShieldThe HSM line from Cambridge's nCipher, which has changed hands twice and still sits inside countless certificate authorities.
- NSO GroupIsraeli firm behind the Pegasus spyware, sold to governments and repeatedly found on the phones of journalists, lawyers and…
- NTDS.ditThe file containing the whole of Active Directory on every domain controller — all objects, all attributes and all password…
- NTLMMicrosoft's legacy authentication protocol — replaced by Kerberos in Active Directory since Windows 2000, but still used as…
- NTLM relayThe attack where you don't crack the authentication, you forward it — the victim logs in to the attacker, who passes the…
- NTP (Network Time Protocol)Protocol for syncing computer clocks against atomic clocks over the internet — millisecond precision.
- NTP amplificationDDoS variant that abuses old NTP servers with the monlist command enabled. Attacker sends a 234-byte query with spoofed…
- NTSC fixAdapting a demo written for PAL machines so it also runs on NTSC — the scene's most stubborn compatibility problem.
- Nuance CommunicationsThe American company behind Dragon dictation, which for two decades was close to synonymous with commercial speech…
- Nucleus sampling (top-p)A sampling method (also "top-p") where the model may only choose among the smallest set of top-candidate tokens whose…
- NuendoSteinberg's DAW for film, TV and game audio – the Cubase engine with post-production tooling bolted on top.
- NUFLIA C64 picture format that pushes the machine toward per-pixel color by stacking the FLI trick on top of a sprite layer that…
- Nuke (warez)Flagging a warez release as broken or rule-breaking so it stops counting on the topsites.
- null"No value". The single biggest source of "NullPointerException" and similar crashes in software history.
- Null cipherA message hidden inside innocent text – every fifth letter, say, or the first letter of each word.
- NULL pointerPointer that doesn't refer to any object. Dereferencing crashes the program (segfault in C/C++, NullPointerException in…
- Null test (audio)A way to tell whether two audio files are identical: flip the polarity of one, sum them, and listen to whatever is left.
- Nullish coalescing (??)JS operator: x ?? "default" — returns default only if x is null or undefined.
- NullsoftThe company behind Winamp, whose name was a dig at Microsoft and whose founder kept releasing things its parent company…
- NUMA (Non-Uniform Memory Access)A multi-socket system where each CPU has "its own" RAM — accessing local memory is faster than cross-socket access over the…
- NUMA balancingThe technique of placing a thread and its data near each other in a NUMA system (Non-Uniform Memory Access), where a CPU…
- NUMA nodeGroup of CPU cores + memory that have fast access to each other. Multi-socket servers and AMD chiplet CPUs have multiple…
- Numa NumaThe 2004 webcam clip where Gary Brolsma sits at his desk lip-syncing a Moldovan pop song with his entire upper body. One of…
- Number Nine Visual TechnologyThe Massachusetts graphics card company that built the first 128-bit graphics chip and named its products after Beatles…
- numlockxA program with exactly one job: switch NumLock on when X starts, so the keypad produces digits from the first keystroke.
- NumPyFoundational package for numerical Python — N-dimensional arrays, broadcasting, vectorized operations. Travis Oliphant…
- NUnit.NET test framework. Port of Java JUnit to .NET (Jim Newkirk + Charlie Poole), 2002. The first major unit testing framework…
- Nushell (Nu)A shell whose pipes carry structured data instead of text streams. Started in 2019 by JT and Yehuda Katz, written in Rust…
- NutanixThe company that popularised hyperconverged infrastructure — servers where compute and storage share a box instead of…
- NUTS (talker)Neil's Unix Talk Server — a tiny talker codebase that let any student start a chat world of their own.
- NuveiCanadian payments processor that was taken private in 2024, having first become the country's largest tech IPO to date.
- NuxtVue.js meta-framework — Sebastien Chopin, 2016. SSR, SSG, file-based routing, auto-imports, server routes. "Next.js for Vue".
- NVDIMMNon-Volatile DIMM — a memory module that retains its contents on power loss. The most common is NVDIMM-N: fast DRAM that on…
- NVGRENetwork Virtualization using GRE — Microsoft's overlay tunneling protocol (RFC 7637), a competitor to VXLAN. It encapsulates…
- NvidiaMade graphics cards for gamers, and thereby happened to build the hardware the entire AI industry turned out to need.
- Nvidia RTX 50 series (Blackwell consumer)Nvidia's consumer chips on Blackwell architecture — RTX 5090 (32 GB GDDR7), 5080, 5070 Ti, 5070. Launched January 2025.
- NVLinkNvidia's proprietary high-bandwidth interconnect between GPUs. NVLink 5 (Blackwell, 2024) = 1.8 TB/s bidirectional per GPU…
- NVMe (Non-Volatile Memory Express)Fast SSD standard that talks directly to PCIe instead of going through the old SATA bus.
- NVMe namespaceA logical division of an NVMe SSD into several independent "devices" at the controller level — each namespace appears as its…
- NVMe-oFNVMe over Fabrics — exposes NVMe SSDs over a network (TCP, RDMA, Fibre Channel). Spec from 2016. Latency 10-20 µs over RDMA…
- NxMonorepo toolchain — Nrwl, 2018 (Victor Savkin, Jeff Cross, ex-Angular team). Focus: smart build cache, affected-test…
- NX (NoMachine)The technique that made X programs usable over modems and ADSL by removing the round trips instead of shrinking the packets.
- NXP SemiconductorsPhilips's old chip division, best known today for the silicon in cars, access badges and contactless payment cards.
- Nyquist frequencyHalf the sample rate — the highest frequency a digital signal can carry before it turns into something else.
- NZBAn XML file listing exactly which Usenet articles make up a download.
- NZXTAmerican maker of PC cases and cooling, known for its Kraken coolers and the CAM software.
O
- Claude OpusAnthropic's top-tier model. Opus 4.7 (2026) is the latest. Standard choice for hard reasoning, agentic tasks, code…
- Intel Optane (3D XPoint)Intel + Micron's "new memory tech between DRAM and NAND" — launched 2017, discontinued 2022 after underwhelming market…
- O-RAN (Open RAN)Open Radio Access Network — disaggregate mobile-network radio + control software from single-vendor monolithic equipment…
- O3DE (Open 3D Engine)Amazon's Lumberyard game engine, reworked and handed to the Linux Foundation as open source.
- OAEP paddingA padding scheme for RSA encryption that makes the ciphertext randomised and closes the easiest routes to Bleichenbacher's…
- OAM (Object Attribute Memory)The small block of memory where a video chip keeps its sprite attributes — position, tile number and colour — one row per…
- OAuthThe protocol that lets a site sign you in via Google/Facebook/GitHub without seeing your password.
- OAuth 2.0 (RFC 6749)The authorization framework — "let an app access my X data without me sharing my password". Not authentication (that's OIDC…
- OAuth scopesGranular permissions an OAuth app requests — read:user, write:repo, delete:files.
- OberheimTom Oberheim's synth brand, which built polyphony out of linked monophonic modules and gave 1980s pop its thick brass stabs.
- Oberon SystemETH Zürich's operating system from 1987, written by Niklaus Wirth and Jürg Gutknecht, where the screen is tiled text and any…
- ObfuscationDeliberately making code hard to read — variable names like _0x4a8b, rewrites like 1+1 becoming !![]+!![].
- ObjectEncapsulation of data (fields) + behavior (methods) as a unit in OOP. An instance of a class. Everything-is-an-object…
- Object poolingReusing a pre-allocated set of objects instead of constantly creating and discarding them, to avoid allocation cost and GC…
- Object spaceA model's own coordinate system, where its vertices live before anyone has decided where in the world it belongs.
- Object storageStorage where data lives as named objects in a flat namespace, fetched over HTTP rather than mounted as a filesystem.
- Objective-CHybrid of C and Smalltalk. Brad Cox + Tom Love, 1984. NeXT (Steve Jobs) acquired it in 1988 → became Apple's primary…
- OboeGoogle's C++ library for low-latency audio on Android, which picks AAudio or OpenSL ES for you depending on what phone the…
- OBS Studio (Open Broadcaster Software)The program practically every live broadcast on the internet passes through. Free and open source, started in 2012 by Hugh…
- Observability (o11y)The ability to understand what a system is doing from the inside just by looking at its outputs — metrics, logs, traces.
- Observer patternAn object (subject) holds a list of "observers" and notifies them when it changes. Foundation of reactive programming, event…
- ObsidianMarkdown-based note app — your files are plain .md on disk, you own them. Wikilink-style, graph view, 1500+ community…
- OCamlPragmatic functional language in the ML family — INRIA France, 1996. Static types with inference, algebraic data types…
- OCBA 2001 mode of operation that encrypts and authenticates in a single pass, using one block cipher call per block.
- OccluderA piece of geometry that hides others and is therefore used to avoid drawing what cannot be seen behind it.
- Occlusion cullingNot drawing what is hidden behind something else — the cheapest geometry is the geometry never sent to the GPU.
- Occlusion queryA GPU query that counts how many pixels an object would actually draw, so the engine can skip it when the answer is zero…
- Ocean SoftwareThe Manchester publisher that turned film licences into an industry on 8-bit home computers.
- OCI (Open Container Initiative)Linux Foundation-governed project that standardizes the container format. Founded 2015 by Docker, CoreOS and others. Three…
- OCI imageOpen Container Initiative Image Spec — standardized format for container images. Descends from Docker v2 manifest…
- oclockA round clock with no window frame: the demonstration program for the Shape extension, which in 1989 let an X window be…
- OCR (Optical Character Recognition)Reading text out of images — receipts, invoices, old books, signs.
- OCR-AThe typeface drawn for machine eyes first and human eyes second — which is exactly why it served as visual shorthand for…
- OCR-BAdrian Frutiger's 1968 typeface, drawn so that machines and humans read it equally easily.
- OCSThe Amiga's original chipset from 1985 — Agnus, Denise and Paula, the three chips that gave the machine graphics and sound…
- OCSP (Online Certificate Status Protocol)Protocol for real-time checks on whether a TLS certificate has been revoked. RFC 6960. Browser asks the CA's OCSP responder…
- Octahedral encodingPacks a unit normal into two numbers by folding the unit sphere onto an octahedron unwrapped across a square.
- OctaMEDAmiga tracker that squeezed four hardware channels into eight through software mixing.
- OctreeA tree that splits 3D space into eight boxes again and again, so you only test objects that actually sit near each other.
- OCuLinkA cable standard (SFF-8611/8612) that runs raw PCIe lanes outside the chassis. Popular for external GPUs to handheld gaming…
- OCZ TechnologyThe SSD brand that bought its own controller maker, grew fast on aggressive marketing, and went bankrupt about as fast.
- Oded GoldreichThe third letter in several of theoretical cryptography's most important acronyms.
- Oded RegevIsraeli computer scientist whose Learning With Errors problem became the foundation of most post-quantum cryptography.
- OdinSamsung's internal Windows tool for flashing firmware onto Galaxy devices, never officially released yet found in every…
- ODR (One Definition Rule)The rule that each thing may be defined exactly once in a program, and that whatever may be defined more than once must be…
- OFB modeA block cipher mode that turns the cipher into a synchronous stream cipher by feeding its own output back in.
- OFDMSplitting a wide channel into thousands of narrow subcarriers transmitted in parallel — the foundation of wifi, 4G, 5G and…
- OFDMA (WiFi)Orthogonal Frequency-Division Multiple Access — a key feature in WiFi 6 (802.11ax) that splits a channel into smaller…
- Off-mesh linkA hand-placed connection that stitches together two otherwise separate parts of a navmesh so an agent can jump, climb or…
- Offensive SecurityThe company behind Kali Linux and the OSCP, a certification you can't pass by memorising multiple-choice answers.
- Offline readerA program that let you read and answer BBS mail while disconnected, so the connection was only needed to fetch and drop off.
- Ofir ArkinIsraeli network security researcher who showed how much an operating system gives away simply by the way it answers ICMP.
- OGRE (rendering engine)A rendering engine on purpose — not a full game engine, just the graphics part done properly.
- OIDC (OpenID Connect)Identity layer on top of OAuth 2.0 — the technical basis for "Sign in with Google/Microsoft/Apple".
- OidosA synth for 4k intros that builds sound from thousands of sine waves instead of filters and oscillators.
- Oki MicrolineA dot matrix line that started in 1980 and is still in production, for the simple reason that a carbon copy requires a…
- OkidataJapanese printers so durable that nine-pin Microline units still churn out shipping labels.
- OKLCHCSS colour function specifying lightness, chroma and hue in a perceptual colour space, where the same lightness value…
- OktaEnterprise SSO — employees log in once and get access to all their SaaS apps. Competes with Microsoft Entra ID (Azure AD).
- OktalyzerAn early Amiga tracker that squeezed eight channels out of a machine with four.
- OLAP (Online Analytical Processing)Databases optimised for large analytical queries — "crunch all data from the last 5 years".
- OldskoolThe demoscene's dividing line between squeezing fixed hardware and drawing 3D on a PC — and, in time, a whole aesthetic of…
- OLEDDisplay tech where each pixel is its own LED — true black (pixel off), unmatched contrast.
- OLGXSun's OPEN LOOK Graphics Library: the C library that drew buttons, elevators and pushpins for both the olwm window manager…
- OLITAT&T's toolkit for OPEN LOOK, built on the X Toolkit Intrinsics.
- OlivettiItalian typewriter maker from Ivrea that built one of the first desktop computers and later sold PC clones to half of Europe.
- OllamaTool for running LLMs locally on your own machine — ollama run llama3 and you're chatting.
- OLTP (Online Transaction Processing)Databases optimised for many small transactions — typically operational data in an app.
- olvwmThe OPEN LOOK Virtual Window Manager: Sun's olwm plus a virtual desktop and a map of the whole thing.
- olwmThe OPEN LOOK window manager in Sun's OpenWindows, with pinnable menus and a mouse button for every purpose.
- OMACA single-key CBC-MAC variant that fixes the variable-length problem; the forerunner of CMAC.
- OMEMOE2EE extension for XMPP, based on the Signal Protocol. XEP-0384. Developed by Andreas Straub in 2015 for Conversations…
- OMF (Open Media Framework)Avid's 1990s interchange format for moving an edited timeline between applications — the predecessor of AAF, and still the…
- Omnidirectional scannerA reader that catches the code however the package is turned, by sweeping the beam in a starburst rather than a single line.
- Omnidirectional shadow mapsShadow maps for point lights, which cast shadows in every direction — usually solved by rendering depth into a six-faced…
- OmnisphereSpectrasonics' 2008 software synth, known for an enormous sound library and for turning up in roughly every other film…
- OMROptical mark recognition — the machine sees where someone filled a bubble by how it reflects light, the basis of test and…
- OmronJapanese automation company behind everything from industrial relays to blood-pressure monitors and the first automated…
- On Computable NumbersAlan Turing's 1936 paper, which invented the computer as a mathematical object before anyone had built one.
- On-callWhen someone on the team is responsible for answering production alerts outside working hours.
- On-die termination (ODT)Termination resistors built into the memory/controller chip itself rather than on the motherboard, to dampen signal…
- One UISamsung's skin on top of Android — designed so big screens can still be reached with one thumb.
- One-time padThe only cipher proven unbreakable, and the only one almost nobody can be bothered to use.
- One-way functionA function that is easy to compute forwards but practically impossible to invert.
- One-way platformA platform you can jump up through from below but land on from above — collision in one direction only.
- OneDriveMicrosoft's cloud file storage. Launched in 2007 as Windows Live Folders, later SkyDrive, renamed OneDrive in 2014 after…
- Onel de GuzmanFilipino student behind ILOVEYOU, the email worm that circled the globe in a couple of days in May 2000 and for which he…
- OnelinerThe one-line message board on a BBS — every caller got to leave a single line shown to the next, a graffiti wall in real…
- OneLoginA cloud login service that spent a decade chasing Okta before being swallowed by another identity vendor.
- OnePlusThe phone brand that sold flagship specs at mid-range prices under the slogan "Never Settle" — and then quietly folded back…
- Onion skinningShowing translucent ghost images of the neighbouring frames at the same time, so the animator can see the motion between…
- Online cipherA length-preserving cipher in which each ciphertext block depends only on the plaintext up to and including that position.
- OnlyFansBritish subscription platform — fans pay monthly for creator content, mostly associated with adult material.
- ONNXOpen exchange format for ML models — train in PyTorch, export to ONNX, run in browser or mobile.
- onsemiMotorola's old components division, today focused on power and image sensors for the car industry.
- Onset detectionAutomatically finding the moments in a recording where a new note or hit begins.
- Onur MutluComputer architect whose group showed you can flip bits in memory just by reading the neighbouring rows often enough.
- OOM killerLinux's last resort under memory pressure: pick a process and kill it, rather than let the whole system stall.
- OomaHome phone service that sold a one-time box and let the calls be free afterwards.
- OOP (Object-Oriented Programming)A programming style where code is organised around "objects" that combine data and behaviour.
- OPA (Open Policy Agent)Generic policy engine — "is this user allowed to do X on resource Y?". Rego is the language.
- OPA & RegoOpen Policy Agent — general policy engine that takes JSON input and returns allow/deny. Rego is its declarative language…
- OPA GatekeeperPolicy engine that sits in the Kubernetes admission chain and rejects resources that break the rules, before they ever get…
- OPAQUEAsymmetric PAKE: password-authenticated key exchange where the server never sees the password. Jarecki + Krawczyk + Xu…
- Opaque moveMoving a window with its contents visible for the whole drag instead of as an empty outline, a luxury early window managers…
- OPC drumThe light-sensitive cylinder inside a laser printer, coated in a layer that wears out on a completely different schedule…
- OPC UA (OPC Unified Architecture)Industrial standard for data exchange in factories — abstracts all underlying protocols (Modbus, Profinet, etc.) behind a…
- OpcodeThe number at the start of an instruction saying which of the processor's hundreds of operations is meant.
- Open Cubic PlayerThe most lavish module player of the DOS era, with per-channel views, spectrum analysers and oscilloscopes in text mode…
- Open Desktop (SCO)SCO's 1990 bundle of Unix, X11, Motif and a desktop for an ordinary 386 PC: the first graphical 32-bit system for the PC…
- Open Dynamics Engine (ODE)One of the first free libraries for articulated rigid-body physics, and for years the default choice for robot simulation.
- Open Graph (OG tags)Meta tags that control how a link looks when shared on Facebook, LinkedIn, iMessage, Discord.
- OPEN LOOKSun and AT&T's interface specification for Unix — more carefully thought out than Motif, and it lost anyway.
- Open redirectVulnerability where a ?redirect= parameter accepts any URL — phishers can make the link look like it goes to your site but…
- Open Sound Control (OSC)A message format for controlling sound and music software over a network, built as an answer to everything MIDI could not do.
- Open Sound System (OSS)The first common audio API in the Unix world, where the sound card was a file you wrote samples to.
- Open sourceSoftware with source code publicly available + a license allowing inspection, modification, redistribution. Term coined 1998…
- Open source LLM (Open weights)A language model whose weights you can download and run yourself. Almost always a misleading term — the accurate one is open…
- Open-reel tapeTwo exposed reels threaded past the heads by hand — the dominant mainframe storage format from the 1950s into the 1980s.
- OpenAIAI research company founded 2015 by Sam Altman, Elon Musk, Ilya Sutskever, Greg Brockman and others. Switched from nonprofit…
- OpenAI o1OpenAI's first reasoning model (September 2024) — emits an internal "thinking" CoT phase before answering and proved that…
- OpenALA cross-platform API for positional audio in games, deliberately designed to look like OpenGL.
- OpenAPIStandard for describing REST APIs. The fork from Swagger 2.0 → donated to Linux Foundation 2015 → OpenAPI Specification…
- OpenboxThe Blackbox descendant that became a pure window manager with no panels of its own, and so made a good engine for other…
- OpenBSDThe BSD variant that puts security and code correctness above all else — and the origin of OpenSSH.
- OpenCLAn open standard for running computation on GPUs, CPUs and FPGAs from the same source — the vendor-neutral counterweight to…
- OpenCVOpen-source computer vision library. Gary Bradski, Intel, 2000. C++ core with Python/Java/JavaScript bindings. De-facto…
- openGaussHuawei's open-source database, forked from PostgreSQL 9.2 and tuned for Chinese hardware.
- OpenGLCross-platform 3D graphics API from 1992 (Silicon Graphics, then Khronos). Standard for games, CAD, viz for decades. Now…
- OpenID Connect (OIDC)Identity layer on top of OAuth 2.0 — where OAuth grants access tokens, OIDC says who you are via a signed ID token (JWT).
- Opening the bordersFooling the VIC-II into never closing the border, so sprites can be drawn in the normally blank edge.
- OpenLayersOpen source JavaScript library for interactive maps. MetaCarta, 2006. OSGeo project. Supports WMS, WFS, vector tiles…
- OpenLLMetryOpenTelemetry instrumentation for LLM/RAG/Agent frameworks (OpenAI SDK, LangChain, LlamaIndex etc.) — ships traces to any…
- OpenManageDell's software suite for monitoring and running PowerEdge servers from a distance.
- OpenMPTThe Windows tracker that learned to read nearly every module format ever written — the heir to ModPlug Tracker and the glue…
- OpenPGPThe standard that turned PGP into a format anyone may implement — and that thereby inherited all of its thirty-year-old…
- openQASUSE's test framework that installs an entire operating system in a virtual machine and checks the result by recognising…
- OpenRouterOne API key gives access to 300+ LLMs from Anthropic, OpenAI, Google, Meta, DeepSeek and others — pay per token, automatic…
- OpenSearchAmazon's fork of Elasticsearch 7.10 — started January 2021 after Elasticsearch's licence change to SSPL/Elastic License…
- OpenShiftRed Hat's enterprise Kubernetes distribution — opinionated, security-hardened, with built-in CI/CD, image registry…
- OpenSL ESKhronos's standard audio API for embedded and mobile devices, best known as the only way to play sound from native code on…
- OpenSSLDominant TLS + crypto library. Open source since 1998. Powers practically all HTTPS on the internet (nginx, Apache, Postfix…
- OpenStepNeXTSTEP's programming interface pried loose from its operating system, specified by NeXT and Sun in 1994 and later the…
- OpenStreetMap (OSM)The world's map built like a wiki — freely licensed geodata anyone may edit and use.
- openSUSESUSE's community distribution, as recognisable for the green chameleon Geeko as for its two faces: the stable Leap and the…
- openSUSE LeapThe point-release openSUSE branch that has shared a binary core with SUSE's commercial Linux since 2015.
- openSUSE TumbleweedopenSUSE's rolling-release distribution — always fresh software, machine-tested before it ships.
- OpenTelemetry (OTel)Vendor-neutral standard for emitting traces, metrics and logs from applications.
- OpenTelemetry (OTel)The CNCF project that standardises instrumentation for traces, metrics and logs — the antidote to vendor lock-in on…
- OpenTextCanadian software company that got big on document management and then bigger still by buying other people's mature software.
- OpenTofuOpen source fork of Terraform — after HashiCorp switched to the restrictive BSL licence in 2023.
- OpenVMSThe VAX operating system built never to go down, whose architect then went off and wrote Windows NT.
- OpenVPNClassic VPN implementation — built on TLS, runs in userspace, port 1194 UDP/TCP.
- OpenVRValve's API for VR apps, with SteamVR as the runtime, meant to let a game talk to any headset instead of one vendor at a…
- OpenWindowsSun's desktop bundle for SunOS and Solaris, built on OPEN LOOK and a server that spoke both X11 and NeWS.
- OpenWrtA Linux distribution for routers and other network gear. It emerged in 2004 after Linksys was compelled to release the…
- Opera SoftwareNorwegian browser company that invented half of what you take for granted in a browser and rarely got paid for it.
- Operating system (OS)The software layer between applications and hardware — schedules CPU, manages memory, abstracts file system, drivers…
- Operation BuccaneerThe US Customs Service's coordinated strike against the top tier of the warez scene in December 2001.
- Operation SundevilThe US Secret Service's nationwide sweep of the BBS underground in May 1990 — lots of seizures, very few convictions.
- Operational Transformation (OT)Algorithm family for conflict-free concurrent editing — multiple users can write to the same document without locking…
- OperatorA Kubernetes pattern encoding operational knowledge about an application as a controller: a CRD plus a loop that keeps…
- OperServThe part of an IRC network's services reserved for operators, used for network-wide bans and housekeeping.
- OPFS (Origin Private File System)A private file system each site gets to itself, invisible to the user and with no dialogs. The thing that finally made real…
- OPL (FM synthesis)Yamaha's FM synthesis chip — the sound of DOS games before sample-based cards took over.
- OPNsenseFreeBSD-based firewall + router. Fork from pfSense 2014 after community conflict with Netgate. Dutch Deciso BV maintains…
- OppoChinese phone maker from the BBK orbit, sibling to Vivo, OnePlus and Realme.
- OPSECOperations Security — discipline of protecting small details that together reveal sensitive info or identity. Military…
- OptaneIntel/Micron persistent memory (3D XPoint tech). Launched 2017 as "third tier" between DRAM and NAND SSD. Lower latency than…
- Optical compressorA compressor in which the signal lights a lamp and a photocell beside it turns the gain down — slowly, smoothly and a little…
- Optical discStorage media read with a laser. Data sits as pits and lands along a spiral track beneath a protective polycarbonate layer…
- Optical interconnect (CPO, co-packaged optics)Optical link directly at the switch/CPU package — eliminates copper trace to "normal" pluggable optical transceiver…
- Optical pickup unitThe laser-and-lens assembly that focuses the beam onto the disc and reads the reflection in every optical drive — and the…
- Optimistic concurrencyAssume conflicts are rare — let everyone write, detect conflict at commit, retry.
- OptimizelyAn A/B testing and experimentation platform that later grew into a broader digital-experience suite.
- Optional / Maybe typeType that explicitly can be "empty" — Option<T> in Rust, T? in Kotlin/Swift, Maybe T in Haskell.
- OptiPlexDell's office desktop — grey, unremarkable and built to be bought by the thousand by an IT department, not an enthusiast.
- OpusOpen, royalty-free audio codec built for real time — the standard in voice calls, Discord and WebRTC.
- Opus-CBCSThe BBS package that competed with Fido for the loyalty of FidoNet sysops in the second half of the 1980s.
- OracleBuilt the first commercial relational database system and became enterprise software's most feared licensor.
- OrbStackMac Docker Desktop alternative. Native Swift + Apple Virtualization framework (no QEMU). Startup <3 sec (vs Docker Desktop…
- ORCOptimized Row Columnar — columnar file format for analytics. Hortonworks 2013 (for Hive). Competitor to Parquet — Hive…
- ORCA (Optimal Reciprocal Collision Avoidance)RVO's successor: cast avoidance as a linear program and pick the allowed velocity closest to the one you actually wanted.
- Orca SecurityThe cloud-security firm that turned "agentless" into a sales pitch — reading an entire cloud account from snapshots instead…
- OrchestrationAutomated management of many containers/services — scheduling, health checks, restarts, scaling.
- Order-independent transparencyThe umbrella term for techniques that render transparent surfaces correctly without first sorting them back-to-front.
- Ordered ditheringA dithering method that decides each pixel's rounding against a fixed threshold matrix rather than spreading the error…
- Org-modeAn Emacs mode for structured text that has grown into a complete system for notes, task management, planning and literate…
- Oric-1A British home computer from 1983 that flopped at home but became a favourite in France, where it took on the ZX Spectrum.
- OrientDBGraph, document, key-value and object models in one engine, queried with SQL syntax extended for graph traversal.
- Oriented bounding box (OBB)A box that rotates with its object, unlike the axis-aligned AABB — a tighter fit, but costlier to test.
- Origin lineThe * Origin: line at the foot of an echomail post, naming the BBS it was written on and that board's FidoNet address.
- Origin Private File System (OPFS)A high-speed, private file system that a website gets in the browser, isolated per origin and invisible to the user…
- Origin Systems"We create worlds," said the boxes, and for once the slogan was an understatement.
- Orin KerrAmerican law professor who has spent his career on the question computer-crime statutes never quite answer: what does…
- OrkutGoogle's first social network, launched in January 2004 — the same week as Facebook. Named after the developer Orkut…
- ORM (Object-Relational Mapping)Library that lets you talk to the database via objects instead of SQL.
- OroborusA minimalist stacking window manager from the early 2000s, best remembered as the skeleton xfwm4 was built on.
- Orphan ruleRust's rule that you may only implement a trait for a type if at least one of them belongs to your own crate. The source of…
- Orr DunkelmanIsraeli cryptanalyst who has spent a career finding cracks in block ciphers everyone else assumed were solid.
- OS/2IBM and Microsoft's joint successor to DOS — which ended with the two building separate operating systems and becoming…
- Osborne ComputerMaker of the first commercially successful portable computer, best remembered for a business blunder that now bears its name.
- OSF (Open Software Foundation)The consortium seven Unix vendors formed in 1988 so as not to leave Unix to AT&T and Sun, which gave the world Motif, OSF/1…
- OSF/Motif Style GuideThe book that made Motif more than a toolkit: rules for how menus, dialogs, keyboard and mouse must behave, with a checklist…
- OSGiDynamic modules for Java, with versioned dependencies and the ability to swap code out while the process keeps running.
- OSI modelConceptual 7-layer model for networking: Physical → Data Link → Network → Transport → Session → Presentation → Application.
- OSPF"Open Shortest Path First" — Interior Gateway Protocol (IGP) for routing inside an autonomous system. Link-state protocol…
- OSPF areaOSPF divides a large network into "areas" to limit how far routing information (LSAs) spreads — otherwise every router would…
- OSPF DR/BDROn a shared (multiaccess) network like Ethernet, OSPF elects a Designated Router (DR) and a Backup DR (BDR) that all other…
- OSPF LSALink-State Advertisement — the building blocks OSPF routers exchange to describe the network's topology. Each router…
- OTA updateUpdating the system wirelessly rather than by plugging the device into a computer — over the air.
- OTel Collector (OpenTelemetry Collector)Vendor-neutral pipeline for traces, metrics, and logs — receivers in, processors in the middle, exporters out.
- OTP (One-Time Password)One-time code valid for a short window — typically 6 digits, changing every 30 seconds.
- Ottendorf cipherA book cipher in which each letter is written as a position inside an agreed book.
- OuluBoxThe University of Oulu's BBS, whose chat feature IRC was written to replace.
- Out-of-order executionWhen a CPU runs instructions in a different order than the program was written, to avoid waiting. While one instruction…
- Outbox patternSolve the "dual write" problem (database + message queue in the same transaction) by writing the event to an outbox table at…
- Outline renderingDrawing clean outlines around objects — the hallmark of the toon look and of highlighting a selected thing.
- OutlookMicrosoft's email client — desktop Outlook since 1997, replaced Hotmail/Live on the web in 2012. Dominates enterprise…
- Output parsing (LLM)Parsing and extracting structured data from an LLM's text answer — and handling when the model doesn't follow the requested…
- OutreachAutomates a sales team's outbound contact into scheduled sequences of emails, calls and reminders — the factory behind every…
- OverclockingRunning a processor, graphics card or memory faster than the manufacturer specified. It almost always requires more voltage…
- OverdrawWhen the same pixel is shaded more than once in a frame because several surfaces cover it — wasted work for the GPU.
- Overdrive (guitar effect)The pedal that imitates a valve amp turned up too far — soft clipping, as opposed to fuzz's hard edge.
- OverdubRecording a new part while listening back to what's already on tape, so a song can be built up one layer at a time.
- OverfittingWhen an ML model memorises training data instead of learning general patterns — good on training, bad in the wild.
- Overlap-addChopping a long signal into blocks, processing each block on its own and summing the overlapping tails afterwards.
- Overlay planes (X11)Extra bitplanes sitting on top of the normal framebuffer, so menus and cursors could appear and vanish without the image…
- overlayfsThe union filesystem in the Linux kernel that stacks a container image's layers into a single coherent filesystem, with a…
- Override-redirectA flag on an X11 window that tells the window manager to keep its hands off.
- OversamplingTemporarily working at a higher sample rate than the final output, so aliasing products land somewhere they can be filtered…
- OverscanThe picture area beyond the "safe" visible frame — the edge a TV normally crops, but which demo coders fought to draw into.
- OverstrikeBacking up one position and hitting the same spot again — the whole of typography as an impact machine understood it.
- OvertureThe company that invented the search ad where advertisers bid for position and pay per click.
- OVHcloudEurope's largest homegrown cloud provider, out of Roubaix in northern France, known for cheap dedicated servers and for…
- OWASP (Open Web Application Security Project)A non-profit that maintains "OWASP Top 10" — a regularly updated list of the most common web vulnerabilities.
- OWASP Top 10Industry-standard list of the 10 most critical web application security risks. OWASP (Open Worldwide Application Security…
- Owen WalkerNew Zealand teenager, a.k.a. AKILL, who wrote botnet code during the FBI's Operation Bot Roast and got a job instead of a…
- OwncastSelf-hosted livestreaming server — an open source alternative to Twitch/YouTube Live that you run on your own hardware. A…
- OwnershipRust's memory management model: every value has exactly one owner; when the owner goes out of scope, the memory is freed…
- Oxblood RuffinCanadian cDc member who recast hacktivism as a programme for free information rather than a weapon.
- oxcOxidation Compiler — Rust-based JS/TS toolchain. Boshen Chen + Void(0), 2023. Sub-projects: oxlint (linter, 50-100x faster…
- OxyronA German C64 group that specialises in finding things the VIC-II chip shouldn't be able to do.
- OzoneBluesky's open source moderation tool. A complete stack for reviewing reports, making decisions, and publishing labels…
P
- @position-tryThe rules that tell the browser what to do when an anchor-positioned element doesn't fit where it was supposed to go.
- Apache ParquetColumnar file format for analytics — compressed, splittable, self-describing with embedded statistics per column chunk. The…
- Apache PulsarDistributed messaging platform. Yahoo internal 2013, open-sourced 2016, Apache top-level 2018. Competitor to Kafka with…
- Google Cloud Pub/SubGCP's fully managed pub-sub service — global, autoscaled, at-least-once delivery, polling or push. "Kafka-ish without owning…
- Modular PSUPower supply where cables can be plugged in/out on the PSU side instead of permanently attached. Fully-modular (all cables…
- Neural network pruningRemoves weights/neurons that contribute little — shrinks model + speeds up inference. Song Han popularised it 2015 with Deep…
- P vs NPComputer science's most famous open problem. Are problems that are quickly verifiable (NP) also quickly solvable (P)? Most…
- P-boxA permutation box that moves bits between positions so that each changed input bit affects many output bits.
- P-core (Performance core)The large, powerful core type in a heterogeneous chip — optimized for maximum single-thread performance. A wide, deep…
- P2P (Peer-to-Peer)Network architecture where every node is equal — no central server.
- P2PEEncrypting card data inside the terminal, so the shop's till system sees nothing but ciphertext all the way to the payment…
- p5.jsJavaScript port of Processing — creative-coding library for art, design, education. Lauren McCarthy, 2014. setup() + draw()…
- PA-RISCHP's own RISC architecture from 1986 that powered the HP 9000 machines for two decades before Itanium took over.
- PaaS (Platform as a Service)Cloud services that host your app without you managing servers/OS. You push code, the platform runs it. Between IaaS (pure…
- PabloDrawA cross-platform editor for ANSI and ASCII art with support for real-time collaboration over the network.
- PAC validationA Kerberos ticket proves who you are; the PAC inside it claims what you're allowed to do. Validation is the check that this…
- Pac-ManThe arcade's biggest success, deliberately designed to attract someone other than young men who liked shooting spaceships.
- Packard BellThe cheap home PC from the department store, built on a borrowed radio brand and a reputation worse than the machines.
- PackerHashiCorp tool for building machine images — AMIs, Docker images, Azure images, from the same config.
- PacketThe smallest unit of data sent over an IP network.
- Packet lossWhen packets disappear in transit — TCP retransmits, UDP doesn't.
- Packet sniffingCapturing and reading network traffic passing an interface. The fundamental tool for all network troubleshooting — and the…
- Packet switchingSplitting data into packets routed individually, instead of reserving a dedicated circuit.
- PacktroSmall intro in front of a compilation disk, made by the group that packed it.
- pacman (package manager)Arch Linux's package manager — known for being extremely fast and syntactically efficient (pacman -S nginx).
- PaddingExtra bytes added to a plaintext so that it fills a whole number of blocks.
- Padding oracleIf the system tells you the padding was wrong, it has just told you enough to decrypt the whole message.
- PaddleA payments and billing service that acts as "merchant of record" and shoulders the entire tax burden for software vendors.
- Page cacheThe kernel's cache of file contents in RAM — the reason free memory on a Linux server always looks alarmingly low.
- Page description languageA programming language that describes a finished page — text, graphics and images with exact placement — independent of…
- Page faultThe trap raised when a process touches a memory address not currently in physical memory — not an error in the usual sense.
- Page flippingChanging which framebuffer the display reads from instead of copying the finished image — one pointer is swapped at the…
- Page printerA printer that composes and outputs a whole page at a time, unlike line and character printers.
- Page table walkThe process of translating a virtual address to a physical one by stepping through the multiple levels of page tables in…
- PagedAttentionA virtual-memory trick for the KV cache that lets LLM servers batch multiple requests without wasting GPU memory.
- Pager (desktop)The small map of every virtual desktop, windows drawn as rectangles, that you click to switch desktops or drag a window…
- PagerDutyThe service that decides who gets woken up at 3 a.m. when production is on fire.
- PagingDividing memory into equal-sized chunks, typically 4 kB, rather than treating it as one contiguous space.
- Paige ThompsonFormer AWS engineer behind the Capital One breach, cloud security's most-quoted SSRF case study.
- Paint workletLets you register a JavaScript class that draws directly into a CSS property: background-image: paint(myPattern).
- Painter's algorithmDraw the scene back to front, letting nearer things paint over what lies farther away — just as a painter builds up a canvas…
- PAK fileQuake's asset archive: one flat file with real paths inside, so the engine could pretend it was reading an ordinary…
- PalantirThe analytics firm that stitches governments' and corporations' scattered data into a single searchable picture – named…
- Palantir AIP (Artificial Intelligence Platform)Palantir's layer for turning language models loose on a company's own data, using the existing ontology as the gate on what…
- Palantir FoundryPalantir's civilian data platform — the same idea as Gotham but aimed at business, built around an "ontology" of the…
- Palantir GothamPalantir's original platform, built for intelligence and defense agencies to tie scattered data sources together.
- Palette AnimationGraphics technique where color palettes rotate rapidly, creating the illusion of motion without moving any pixels.
- Palette cyclingAnimating an image by rotating the entries in its colour palette instead of redrawing a single pixel.
- Palette fadeFading the whole screen to black, white or any colour by recalculating the palette frame by frame and nothing else.
- Palette swapReusing the same sprite or tile with a different color lookup table to get new-looking graphics almost for free.
- PalmThe company that made the handheld organiser an everyday object, then changed owners more often than operating systems.
- Palm OSThe OS that ran the handheld organisers of the 1990s — fast, frugal, and built for a stylus rather than a keyboard.
- Palo Alto NetworksThe company that taught firewalls to ask which application the traffic belongs to, rather than which port it happens to use.
- PAMPrivileged Access Management — systems and procedures for controlling, monitoring, and securing the most powerful accounts…
- PAM4Signalling with four amplitude levels instead of two, doubling the bits per symbol so you do not have to double the…
- Pan lawThe rule for how much a mixer turns a sound down when it's panned to the centre, so it doesn't seem louder there than at the…
- PanamaA design that was both a hash function and a stream cipher, which looked elegant on paper and turned painful in practice.
- PanasonicThe Osaka company from 1918 that started with a lamp socket, won the video format war with VHS and now makes the battery…
- Panda3DDisney's in-house 3D engine, built for theme-park rides and online games, which went open source and found a second life in…
- pandasPython library for data analysis — the DataFrame structure became the de-facto standard for tabular data. Wes McKinney, AQR…
- PanixThe New York provider that sold shell accounts to ordinary people from 1989, before "ISP" was a job description — and got to…
- Pankaj RohatgiIBM side-channel researcher who co-authored both the template attack and the systematic study of electromagnetic leakage…
- PantsScalable polyglot build system — Python, Go, Java, Scala, Rust, Docker, Helm, shell. v2 (2020) full Rust rewrite.
- Paper jamSheets that snag in a printer's paper path — the most common and most cursed of all printer faults.
- Paper tapePrograms stored as holes in a strip of paper — cheaper than punched cards and impossible to reorder.
- Paper tape punchThe write half of paper tape: a row of solenoids driving holes through paper faster than the eye can follow, and a box that…
- Paper tape readerA device that reads data from the pattern of holes in a paper strip — the punch card reader's cousin for a continuous roll.
- PAR2Parity files that let an incomplete Usenet download be repaired.
- Paradox InteractiveThe Stockholm company that turned maps, provinces and dynastic marriages into an export industry.
- Parallax mappingShifts texture coordinates per pixel by a height map and the viewing angle, so the surface appears to have real depth.
- Parallax occlusion mappingMarches a view ray through a heightmap in the fragment shader so a flat surface gains real parallax and self-occlusion…
- Parallax scrollingScrolling background layers at different speeds to fake depth in a two-dimensional game.
- Parallel compressionBlending a heavily compressed copy of a signal with the original, so quiet detail comes up without flattening the transients.
- ParallelismMultiple computations actually running simultaneously — on different CPU cores, GPU, or SIMD pipelines. Often distinguished…
- ParallelsThe company behind Parallels Desktop, which let Mac owners run Windows without rebooting.
- ParaphonySeveral oscillators each play their own note, but share a single filter and a single envelope.
- ParasocialOne-sided "relationship" where a fan experiences an intimate connection with a creator (streamer, YouTuber, influencer) who…
- ParcelJavaScript bundler. Devon Govett, 2017. "Zero config" — automatic detect HTML entry, transforms TS/SCSS/CSS-modules without…
- Parent-document retrieverA RAG strategy where you match on small "child" chunks (precise search) but return the larger "parent" chunk (or the whole…
- Parisa TabrizGoogle's "Security Princess", who ran security for Chrome and went on to run the whole browser.
- Park Jin HyokA North Korean programmer the US blames for the Sony hack, the Bangladesh Bank heist and WannaCry.
- Parkinson's law"Work expands so as to fill the time available for its completion." — Cyril Northcote Parkinson, 1955.
- Parry windowThe short span of frames during which a parry input counters an attack instead of absorbing it.
- ParseAnalyze structure of input according to a formal grammar → build an AST (Abstract Syntax Tree). Basis for compilers, query…
- ParserCode that takes text and builds a structured representation — typically an AST.
- Partial applicationCreate new function by fixing some arguments of existing function. add(a, b) + const add5 = partial(add, 5) → add5(10) = 15…
- Partial hydrationHydrate only interactive components, not whole page. Reduce JS bundle + CPU cost at load. Pioneered by Marko (eBay, 2014)…
- Partial indexAn index that covers only a subset of rows, defined by a WHERE condition. CREATE INDEX ON orders (created_at) WHERE status =…
- Partial-sum attackA bookkeeping trick that makes the square attack on AES several orders of magnitude cheaper by reusing intermediate results.
- Particle systemA way to draw fuzzy, shapeless phenomena — fire, smoke, rain, sparks, magic — as clouds of thousands of tiny, short-lived…
- Partitioned convolutionSplitting a long impulse response into blocks and convolving each one via FFT, so convolution reverb becomes both affordable…
- Partitioned tablesDB feature: logically one table, physically split into multiple "partitions" based on a partition key. Use case: large…
- PartitioningSplit a large table into smaller physical pieces based on some criterion — date, customer ID, region.
- Partitioning cryptanalysisA generalisation of linear cryptanalysis that sorts plaintexts and ciphertexts into classes and measures how unevenly they…
- Partitioning oracle attackAn attack that crafts one ciphertext valid under thousands of keys, so each server response cuts the list of candidate…
- Party reportThe diskmag staple: a scener's own, cheerfully biased account of a weekend at a demoparty.
- Party versionThe build of a demo handed in just before the compo deadline, complete with the bugs and unfinished scenes that implies.
- PascalNiklaus Wirth's 1970 teaching language that turned out to be surprisingly commercial by way of Turbo Pascal.
- Pascal PaillierFrench cryptographer whose 1999 cryptosystem lets you add two encrypted numbers without anyone decrypting them.
- PascalineA nineteen-year-old's attempt to stop watching his father do tax arithmetic by hand, and the first calculating machine…
- Pass-the-hashWindows attack: a stolen password hash can be used directly for authentication — without knowing the password.
- Pass-the-ticketAn attack where an attacker steals a Kerberos ticket (a TGT or service ticket) from the memory of a compromised machine and…
- PasskeyPasswordless login — a cryptographic keypair synced via iCloud/Google/Microsoft, unlocked with Face ID or a PIN.
- PasskeysPasswordless FIDO2/WebAuthn credentials that sync between your devices via iCloud Keychain, Google Password Manager…
- PassphraseSequence of real words instead of random-character password. "correcthorsebatterystaple" (xkcd 936) popularized the concept…
- PasswordThe secret you use to prove you're you — still today's dominant authentication despite many attempts to retire it.
- Password hashingStoring passwords as deliberately slow, salted hashes rather than fast digests.
- Password Hashing CompetitionThe open 2013–2015 contest meant to give the world a better password hash than bcrypt and PBKDF2 — and which gave it Argon2.
- Password managerSoftware that generates and stores unique passwords in an encrypted vault unlocked with a single master password. The single…
- Password sprayingTry logging in to many accounts with one common password — instead of many passwords against one account.
- Passwordless authenticationLogging in without a password — instead using cryptographic keys (passkeys/FIDO2), biometrics, or one-time links. Since…
- Patch managementStructured process for keeping software up to date — inventory, test, distribute, verify.
- Patch TuesdayMicrosoft's monthly security update — the second Tuesday of the month since 2003.
- PatchbayA panel where every input and output in the studio ends up on a socket, so signal paths can be changed with a short cable…
- Path (Usenet)The Usenet header listing every server a post passed through, separated by exclamation marks, with the origin on the far…
- Path MTU Discovery (PMTUD)The method for working out how large packets can be along the whole path. The sender sets the "don't fragment" flag and…
- Path smoothingPost-processing a jagged, node-by-node path into a natural, straighter line that a character can actually follow.
- Path tracingA rendering method that follows light rays along random bounce paths through the scene and computes global illumination…
- Path traversal (Directory traversal)Vulnerability where the user can navigate outside the intended folder via ../ in file paths.
- pathaliasThe program that worked out how a piece of mail should hop across the UUCP network, so users didn't have to type bang paths…
- PathfindingWorking out how a character gets from A to B without walking into walls — in a fraction of a frame.
- PatreonMonthly-membership platform for creators — fans pay $1–$50/month for exclusive content.
- Patrick WardleFormer NSA hacker turned macOS security's most persistent auditor and supplier of free tools.
- PatroniThe template for highly available PostgreSQL. A Python agent that runs alongside each database node and handles primary…
- Pattern (tracker)The building block of tracker music: a grid where time scrolls downward row by row and every column is a sound channel.
- Pattern matchingLanguage feature: destructure + match values against structural patterns in an expression. ML family (OCaml, Haskell)…
- Pattern tableThe actual 8×8 pixel tiles the NES draws from — two bitplanes per tile give four colours, and the nametable points here.
- Paul KargerAmerican computer security researcher who described in 1974 the compiler backdoor Ken Thompson later made famous.
- Paul KocherThe cryptographer who showed that an implementation leaks its keys through how long it takes and how much power it draws.
- Paul MockapetrisReplaced the central HOSTS.TXT file in 1983 with a distributed naming system — without which the internet would have stopped…
- Paul SyversonThe mathematician at the US Navy's research lab who invented onion routing and helped design Tor.
- Paul van OorschotCanadian security researcher at Carleton University whose work runs from authenticated key exchange to white-box…
- Paul VixieThe man who spent decades maintaining much of the internet's name resolution, then invented the spam blocklist.
- Paula (Amiga)The Amiga's sound chip — four DMA channels of eight-bit sampling that made the MOD format and tracker music possible.
- Pauli gatesThe three basic single-qubit operations X, Y and Z — half-turns about their respective axes on the Bloch sphere.
- Paulo BarretoBrazilian cryptographer who designed Whirlpool with Vincent Rijmen and later gave the world the curves many zero-knowledge…
- PaulstretchAn extreme time-stretching algorithm that turns a few seconds of audio into minutes of drifting, weightless texture.
- Pavel CurtisThe Xerox PARC researcher who started LambdaMOO and later turned the lessons into an online-meetings company.
- PaX TeamThe anonymous developer behind PaX, the Linux patch that invented ASLR and laid out much of the exploit-mitigation toolkit…
- PaxosLeslie Lamport's consensus algorithm (1989) — lets a group of unreliable nodes agree on a value even with partial network…
- Payment facilitator (payfac)A company that holds a single contract with an acquirer and then signs up thousands of small merchants underneath it…
- Payment gatewayThe middleman that takes card details from a web shop's checkout, passes them to the acquirer and comes back with a yes or a…
- Payment HSMAn HSM built for card payments, handling PINs and card cryptograms without a single key ever leaving the box.
- Payment orchestrationA layer between checkout and several payment providers that decides where each payment goes and what happens when it is…
- PayPalOnline payment system. Confinity (Peter Thiel + Max Levchin) + X.com (Elon Musk) merged 1999. eBay acquired in 2002 for…
- payShieldThales' line of payment HSMs, the boxes in bank data centres that translate PIN blocks and check card cryptograms.
- PaytmIndian payments and super-app that soared after the 2016 banknote ban and crashed just as spectacularly at its IPO.
- PBKDF1PBKDF2's predecessor, which hashes password and salt over and over but can never produce a key longer than the hash.
- PBKDF2Password-Based Key Derivation Function 2 (RFC 2898) — makes password-to-key conversion deliberately slow by HMAC-ing…
- PC speakerThe IBM PC's tiny built-in beeper, a 1-bit source that clever programmers still coaxed into playing digital audio.
- PC/GEOSThe 1990 graphical desktop that gave a PC XT with 512 KB a complete window system with scalable fonts and real multitasking…
- PCAPFile format for captured network traffic — packet-by-packet recording for analysis.
- PCBPrinted Circuit Board — the circuit board. Substrate (usually FR-4 glass-fiber epoxy) with copper traces that connect…
- PCB layersThe number of copper layers stacked in a circuit board. More layers provide room for more traces, dedicated power/ground…
- PCBC modePropagating CBC, a variant of CBC meant to spread errors onward that turned out to offer no integrity.
- PCBoardOne of the most widely used commercial BBS packages in the United States through the 1980s and 90s.
- PCFPortable Compiled Format, the binary font format the X server loaded its bitmap fonts from, starting with X11R5 in 1991…
- PCI DSS (Payment Card Industry Data Security Standard)Security standard anyone handling credit card data must follow — required by Visa, MasterCard, Amex.
- PCI PIN SecurityThe card industry's rulebook for how PINs are encrypted, moved and handled — PCI DSS's little sibling, with considerably…
- PCIe (PCI Express)The high-speed bus that GPUs, NVMe SSDs and network cards plug into on the motherboard.
- PCIe 6.0The sixth generation of PCI Express (spec 2022). Doubles bandwidth to 64 GT/s per lane by switching signaling from NRZ to…
- PCIe bifurcationSplitting a single physical x16 PCIe slot into multiple smaller links (x8/x8, x4/x4/x4/x4) at the BIOS level — run several…
- PCIe Gen55th-generation PCIe bus. 32 GT/s per lane — double Gen4. Consumer platforms since Intel Alder Lake / AMD Ryzen 7000 (2022)…
- PCLHewlett-Packard's page description language that drives laser and inkjet printers with compact control codes.
- PCM (pulse-code modulation)The plainest way to store sound digitally: measure the wave's amplitude at regular intervals and write each measurement down…
- PDF (Portable Document Format)Adobe's file format for documents that look the same everywhere — text, layout, fonts, images, vector graphics. ISO 32000…
- PDF417A two-dimensional barcode that stacks rows so it holds a good kilobyte of data.
- PDM (pulse-density modulation)A 1-bit format in which signal level is encoded by how densely the ones arrive, and the standard output of digital MEMS…
- PDP-11The minicomputer Unix was rewritten on — and whose instruction set is still visible in C's syntax.
- PDP-8The first minicomputer to sell in volume — a computer you could put in the lab rather than book time on.
- PeaceNetThe peace movement's own online service from the mid-1980s — early proof that activists could organise by modem.
- Peak meterA level meter that shows a signal's highest peaks rather than how loud it sounds.
- Peak shiftWhen flux transitions crowd together, adjacent readback pulses overlap and shift the peak in time — a bit read a little…
- Pedram AminiThe reverse engineer who packaged fuzzing into a framework anyone could download.
- PEEK and POKEThe BASIC commands that read and wrote a single memory address — and so the home computer's only way around whatever BASIC…
- PeerTubeYouTube alternative for the Fediverse — each instance hosts its own videos, WebTorrent P2P offloads bandwidth.
- PEFTParameter-Efficient Fine-Tuning — the umbrella name for methods that adapt a large model by freezing the base weights and…
- PegatronASUS's manufacturing arm, spun off for exactly the reason Wistron left Acer.
- Peiter ZatkoMudge of the L0pht, who told the US Senate his group could take down the internet in 30 minutes.
- pekwmA Swedish window manager from 2003, out of the aewm++ line, with tabs, Emacs-style key chains and rules that place windows…
- Pen plotterAn output device that draws with actual pens on paper, built for line art rather than text.
- Pending sectorA sector that failed on read and has been flagged for relocation, but is waiting for a write before the drive dares declare…
- PendoMeasures what users actually do inside an app and layers guidance prompts on top of the interface — without the developers…
- Penetration depthHow deeply two overlapping bodies have sunk into each other — the shortest push that separates them, along the contact…
- Penetration test (Pentest)An authorized, time-boxed attack against a system to find vulnerabilities before someone else does. It differs from criminal…
- Pentesting (Penetration testing)Authorised simulation of an attack on a system — to find holes before real attackers do.
- PeopleSoftCalifornia company that made HR software for large organisations and ended up on the receiving end of one of the software…
- PepperA secret value mixed into password hashes alongside the salt, but stored separately from the database.
- Percent hackA way of routing email through an intermediate server, alice%target@relay, from the days when networks could not reach each…
- Percentage-closer filteringA technique for softer shadow edges that samples several neighbouring shadow-map texels, runs the depth comparison for each…
- Perceptual codingLossy audio compression that throws away what the ear would not have noticed anyway, rather than what is mathematically…
- Percolator (transactions)Google's model (2010) for layering distributed ACID transactions on top of a key-value store (Bigtable), via client-driven…
- PerconaOpen source company that drove Percona Server for MySQL (drop-in MySQL fork with extra features), Percona XtraBackup (free…
- Percona Server for MySQLDrop-in MySQL replacement. Percona, 2006. Peter Zaitsev (ex-MySQL AB performance team). Same binary API, more features +…
- Percy LudgateA Dublin accountant designed the world's second computer on paper in 1909, independently of Babbage, and died before anyone…
- Perfect forwardingPassing arguments on to another function without losing whether they were temporaries. The thing that makes make_unique and…
- Perfect secrecyA cipher has perfect secrecy when the ciphertext reveals nothing at all about the plaintext.
- PerformanceHow fast and efficiently a system does its job. Almost always two different measures that get conflated: latency (how long…
- PerlScripting language for system administration + text processing. Larry Wall, 1987. Famous motto: "There's more than one way…
- Perlin noiseA smooth, natural-looking pseudo-random function invented for CGI textures — the seed of a thousand procedural worlds.
- Permissions-PolicyThe HTTP header declaring which browser capabilities a page and its embedded frames may use at all — camera, microphone…
- Perpendicular magnetic recording (PMR)Standing each bit's magnetisation on end instead of laying it flat — so more of them fit before they turn thermally unstable.
- PerplexityA measure of how "confused" a language model is about the next token — lower is better.
- Perplexity (metric)Measure of how "confused" a language model is on test data. Lower = better. Calculated as 2^cross-entropy. Standard…
- Perplexity AIAI-driven search engine — Aravind Srinivas (ex-OpenAI), Denis Yarats, Johnny Ho, Andy Konwinski, 2022. Answers questions…
- Persistent Volume Claim (PVC)A request for storage in Kubernetes: a pod says "I need 10 GB of read/write storage" via a PVC, and Kubernetes matches it to…
- Perspective-correct texture mappingTexture interpolation that accounts for depth, so patterns on tilted surfaces shrink properly toward the horizon instead of…
- Pessimistic concurrencyA concurrency strategy that assumes conflicts are likely and therefore locks data up front (e.g. SELECT ... FOR UPDATE)…
- Peter EckersleyAustralian computer scientist at the EFF who measured how unique your browser is and helped make HTTPS free for everyone.
- Peter G. NeumannSRI International researcher who has been collecting and annotating computer failures in RISKS Digest since 1985.
- Peter GutmannNew Zealand security researcher whose name ended up on a 35-pass wiping method he never thought anyone should actually use.
- Peter JungerThe law professor who wanted to post encryption code on his course website and got a federal appeals court to rule that…
- Peter MontgomeryAmerican mathematician whose multiplication method and curve shape live inside nearly every crypto library.
- Peter panningThe error where an object's shadow detaches from its base so the object seems to float — named after the fairy-tale boy who…
- Peter SchwabeThe cryptographer whose name is on three of NIST's first four post-quantum standards.
- Peter ShipleySan Francisco Bay Area security researcher who took the wardialing method out onto the street and turned it into wardriving.
- Peter ShorThe mathematician who showed in 1994 that a large enough quantum computer would break RSA — launching a whole field that is…
- Peter SwireAmerican lawyer who was the White House's first privacy chief and, after Snowden, sat on the panel that reviewed the NSA.
- Péter SzörHungarian virus researcher who wrote the field's standard textbook on how computer viruses work and how to catch them.
- Peter ThielGerman-American entrepreneur and venture capitalist who co-founded PayPal and Palantir — and became Facebook's first outside…
- PetitPotamA technique that forces a Windows server — ideally a domain controller — to authenticate to an address of the attacker's…
- PetmateA modern PETSCII editor for Windows, macOS and Linux that made it easy to draw C64 character graphics without an actual C64.
- Pets.comThe sock puppet that became better known than the business it advertised.
- PETSCIICommodore's character set — ASCII plus block and line graphics right on the keys, the basis for the C64's on-screen art.
- PEXPHIGS Extension to X: the attempt to give the X server 3D graphics, before OpenGL took the job.
- pf (Packet Filter)OpenBSD's stateful firewall. Daniel Hartmeier, 2001 (replacement for IPFilter due to license issues). Standard BSD firewall…
- PFC (Priority Flow Control)Pausing traffic on an Ethernet link for one priority class at a time rather than all of it. The prerequisite for running…
- pfSenseFreeBSD-based open source firewall + router. Web UI for config. Fork from m0n0wall (2004). Today driven by Netgate. Standard…
- pg_dumpPostgreSQL's logical backup tool. It produces either plain SQL or a compressed archive format that pg_restore can read…
- pg_repackPostgreSQL extension that rebuilds bloated tables and indexes without locking them. The alternative to VACUUM FULL, which…
- pg_stat_statementsThe PostgreSQL extension that answers the question "what is actually taking time in this database". The first thing to…
- pg_trgmPostgreSQL extension measuring string similarity via trigrams and — more importantly — making LIKE '%something%' indexable.
- PGA socketPin Grid Array — a CPU design where the pins sit on the processor itself and press down into holes in the motherboard…
- pgBackRestBackup tool for PostgreSQL built for databases that stopped being pg_dump candidates several terabytes ago.
- PgBouncerLightweight connection pooler for PostgreSQL. Own processes speak PostgreSQL protocol both sides. Protects PG from too many…
- PGliteFull PostgreSQL compiled to WebAssembly — run a real Postgres in the browser (or Node.js, Bun, Deno). Only ~3 MB compressed.
- pglogicalPostgreSQL extension for logical replication. 2ndQuadrant (now EDB) 2015. Forerunner of built-in logical replication (since…
- PGP (Pretty Good Privacy)Classic tool for end-to-end encryption of mail and files — invented by Phil Zimmermann in 1991.
- Pgpool-IIPostgreSQL connection pooler + load balancer + replication-aware proxy. More features than PgBouncer but heavier + more…
- pgvectorPostgres extension that adds a vector type and approximate nearest-neighbour search — makes it possible to store embeddings…
- PhanpyA beautiful, minimalist web-based Mastodon client that runs entirely in the browser — no app to install. Open source, known…
- Phantom powerDC power for the microphone down the same cable as the audio, invisible to anything that doesn't need it.
- Phantom readA transaction runs the same range query twice and gets different row counts — because another transaction INSERTed new…
- PharmacodeA simple binary barcode that steers packaging machines in the drug industry — never meant for checkout scanning.
- Phase correlation meterA meter showing how similar the left and right channels are, on a scale from +1 to −1 – and therefore whether the mix…
- Phase distortion synthesisCasio's answer to FM: a cosine wave is read out at an uneven rate within each cycle, bending it into a sawtooth, a square…
- Phase encoding (PE)A self-clocking tape scheme where each bit is a mid-cell phase transition — the 1600 bpi standard on half-inch nine-track…
- Phase vocoderAn algorithm that chops audio into overlapping windows, recomputes each window's spectrum and phase, and reassembles them at…
- Phase-Change Memory (PCM)Non-volatile memory where bits are stored as amorphous or crystalline state of a chalcogenide alloy — switched via heat.
- Phase-locked loop (PLL)A feedback circuit that locks its own oscillator to the frequency and phase of an incoming signal, which lets it recover a…
- PhaserThe most widely used framework for 2D games in the browser. Written by Richard Davey (Photon Storm), first released in 2013…
- PhenomenaSwedish Amiga demo group, best remembered for the 1991 demo Enigma.
- Phi (Microsoft)Microsoft Research's series of small language models — pioneer of the "textbooks are all you need" thesis: small models…
- Phil KarnAmerican engineer and radio ham who sued the State Department in 1994 for the right to export a floppy disk containing code…
- Phil KatzThe Milwaukee programmer behind PKZIP, whose archive format still sits underneath every JAR, DOCX and APK.
- Phil ZimmermannReleased PGP for free in 1991 and became the subject of a three-year criminal investigation into arms exports.
- Philip StarkUC Berkeley statistician who introduced risk-limiting audits in 2008 — a way to check an electronic election result by…
- Philipp Matthäus HahnThe Württemberg pastor who, between sermons and astronomical clocks, built the first calculating machine you could actually…
- Philippe OechslinSwiss researcher at EPFL who invented rainbow tables in 2003 and turned unsalted password hashes into a matter of seconds.
- PhilipsA Dutch light-bulb factory that became one of the great inventors of storage media, then sold off nearly everything except…
- Phillip Hallam-BakerBritish security architect who went from CERN's early web crowd to the certificate business, and wrote the standard for CAA…
- Phillip RogawayThe designer of OCB and XEX who reminded his colleagues in 2015 that cryptography is political.
- Phind"Google for developers with AI" — searches StackOverflow, GitHub, docs and synthesises code examples with citations. Trains…
- Phineas FisherAnonymous hacktivist who broke into two of the best-known vendors of government spyware and dumped their internals online.
- PhishingFraud where an attacker impersonates someone legitimate (your bank, your company, Microsoft) to extract passwords or money.
- Phishing kitA ready-made "kit" to deploy a fake login page — a copy of Microsoft, a bank, etc.
- PhisonTaiwanese maker of controllers for SSDs, USB drives and memory cards — invisible, but in almost everything.
- Phoenix ContactGerman maker of terminal blocks and industrial components that grew into automation with the PLCnext platform.
- Phoenix TechnologiesThe company that clean-room-cloned the IBM PC BIOS and sold it to anyone who wanted to build a compatible.
- PHONE (VMS)The VMS answer to talk: a split-screen real-time chat with telephone vocabulary all the way down to the receiver.
- Phong shadingA shading method that interpolates surface normals per pixel and so captures highlights in the middle of a polygon — unlike…
- Photoconductor drumThe light-sensitive drum in a laser printer that holds a charge in the dark and sheds it where light lands — the image toner…
- PhotocopierThe office machine that makes another of whatever lands on the glass — analog optics for thirty years, nowadays a scanner…
- Photon mappingA two-pass global-illumination method: shoot photons from the lights, store where they land, then read that map back when…
- Photon microGUIQNX's own window system for embedded real-time systems, built on the same microkernel idea as the operating system: a tiny…
- Photonic chip (silicon photonics)Chip that handles light instead of (or in addition to) electrons — for data transfer or direct optical computation.
- Photonic quantum computingQuantum computers using individual particles of light as qubits — and therefore doing without the refrigerator.
- PhotoplotterA plotter that exposes photographic film instead of drawing with a pen — the machine that turns board designs into physical…
- PhototypesetterA typesetting machine that exposes letters with light onto photographic paper or film instead of casting them in lead — the…
- PHPThe web's workhorse — Rasmus Lerdorf, 1995, as CGI scripts for his homepage. Powers 75 %+ of all websites where the…
- phpBBOpen source forum software in PHP. James Atkinson + Anthony Wilkins, 2000. Together with vBulletin dominated the web forum…
- phpMyAdminThe web interface that has let people administer a MySQL database without ever opening a terminal.
- PhpStormJetBrains IDE for PHP. Launched 2009. Built on the IntelliJ platform. Heavy refactoring + framework-specific features…
- PHPUnitPHP's unit testing framework, and effectively the only one — a direct translation of JUnit into a language that for years…
- PhrackThe hacker magazine that began as text files on a BBS in 1985 and is still published, at long intervals.
- PhreakerA hacker who specialized in compromising telephone switching systems and long-distance networks, often through social…
- PhreakingExploring and fooling the telephone network with tones instead of wires — the forerunner of hacker culture, killed off by…
- Physical modelling synthesisSynthesis that simulates the instrument itself — the string, the tube, the body — rather than imitating the sound it makes.
- Physically based rendering (PBR)A shading model built on energy conservation and measurable material parameters, so a surface looks right under any lighting…
- Physics engineThe subsystem that works out how things fall, bounce and collide — approximately right, never exact.
- Physics islandA group of bodies touching or jointed together, solved as a unit — but independently of every other group.
- Physics materialA reusable bundle of surface properties — chiefly friction and bounce — that you stick on a collider instead of setting the…
- Physics sleepingA body whose motion drops below a threshold is pulled out of the simulation until something wakes it.
- PhysXNVIDIA's physics engine — it started as a dedicated hardware card from Ageia, went GPU-accelerated, and finally turned open…
- Pi1541A Raspberry Pi pretending to be a Commodore 1541 right down to the cycle — so even demos with custom drive code work.
- Piano rollThe MIDI editor's grid: time runs to the right, pitch runs up, and each note is a rectangle whose length is its duration.
- PICO-8The fantasy console that turned stingy limits into a selling point: 128×128 pixels, 16 colours and a hard ceiling on how…
- PicoGUIA window system for handhelds, begun in 2000, in which the server owns both the widgets and the layout, so a client sends "a…
- picomThe standalone X11 compositor that is xcompmgr's third-generation heir: shadows, fading, transparency and vsync for anyone…
- PicoSpanThe command-line conferencing program The WELL ran on — written in Ann Arbor, modelled on CONFER.
- PictBridgeA standard for printing photos straight from camera to printer over USB, with no computer in between.
- PID (Process ID)A unique number the OS assigns to each running process.
- PidginA multi-protocol client that gathered every chat network of its era into one window. It was called Gaim from 1998 until…
- PIE (Proportional Integral controller Enhanced)AQM algorithm from Cisco — RFC 8033. Selected as AQM for the DOCSIS 3.1 cable-modem standard, so present in nearly every…
- Pie menuA menu whose items sit like slices of pie around the pointer, so you choose by direction instead of hitting a row.
- Pierrick GaudryFrench algorithmist who computes record-sized discrete logarithms and factorisations — and in doing so puts a price tag on…
- piewmDon Hopkins's early-1990s variant of tvtwm in which every menu is a circle around the pointer: direction chooses, not…
- Piezo inkjetInkjet technology where a crystal shoves the droplet out mechanically, without ever boiling the ink.
- Pigpen cipherLetters become fragments of grids and crosses, dotted or not — mysterious to look at, trivial in practice.
- PII (Personally Identifiable Information)Data that directly or indirectly identifies a person — name, email, national ID, IP, MAC.
- Piling-up lemmaThe rule for how fast a linear approximation fades when you chain several together.
- Pilot ACEThe cut-down version of Alan Turing's computer design — fast, idiosyncratic, and finished only after he had given up and…
- PIMProtocol Independent Multicast — multicast routing protocol that builds on top of unicast routing table (independent from…
- PIMPL (Pointer to Implementation)Putting all private members behind a pointer to a type only declared in the header and defined in the source file. Also…
- PIN blockThe format that packs a PIN together with card data before encryption, so a captured block does not reveal the PIN.
- Pin message"Pinning" an important message to the top of a chat or channel so it doesn't scroll away. Standard in Slack, Discord…
- Pin projectionThe question of whether a field inside a pinned struct is itself pinned. Rust's answer is that you must choose per field…
- PIN translationDecrypting a PIN block under one key and re-encrypting it under another inside an HSM, so the PIN never appears outside the…
- PIN verification value (PVV)A four-digit value that lets an issuer check a PIN without storing the PIN itself.
- Pinch rollerThe soft rubber wheel that presses tape against the capstan so it feeds forward at a steady speed at all.
- Pinduoduo (PDD)Chinese "group buying" app — invite friends to buy the same thing ⇒ discount. Founded 2015, surpassed Alibaba's valuation…
- Pine (mail client)The University of Washington's email client for normal people — and the origin of the pico editor, and therefore of nano.
- Pine64A hardware maker that sells cheap ARM gadgets and leaves the software to the community.
- PineconeThe first managed-only vector database — kicked off the ML vector-DB wave around 2021, built for enterprise RAG.
- PingA tool for testing whether another computer is reachable — sends a small packet and measures the time to reply.
- Ping IdentityThe Denver company selling federated login to large enterprises long before anyone called it an identity platform.
- PingdomSwedish uptime monitoring that pings your site from around the world and alerts you before customers do.
- PiniaOfficial state management for Vue 3, replacing Vuex in 2022. Eduardo San Martin Morote, 2019. TypeScript-first, simpler API…
- Pink noiseNoise with equal energy in every octave — what sounds even to an ear that thinks in octaves rather than hertz.
- PinterestVisual bookmarking — users "pin" images to themed boards. Weddings, recipes, interiors, tattoos.
- Pinwheel calculatorThe calculating machine's third mechanism: a wheel whose number of protruding pins is set by a lever, devised by a Swede…
- PipeA one-way byte stream between two processes — what makes | in the shell possible.
- Pipe codesShort colour codes like |04 and |15 in BBS software, translated into ANSI sequences on their way to the caller.
- PipedriveAn Estonian sales tool built around a single idea: show deals as cards in a pipeline and push them forward, without the…
- Pipeline parallelismSplitting the model by depth: the first layers live on GPU one, the next set on GPU two and so on. Activations travel…
- Pipeline stall (bubble)When the CPU pipeline is forced to pause because an instruction can't continue — it's waiting for data, a resource, or the…
- Pipeline state object (PSO)An immutable object that bundles nearly all of the GPU's fixed pipeline state — shaders, blending, depth test, vertex layout…
- PipeWireThe Linux multimedia server that replaced both PulseAudio and JACK by pretending to be both — and which started life as a…
- Pitch bendThe MIDI message that bends pitch continuously, and one of the few in 1.0 granted fourteen bits of resolution.
- Pitch detectionWorking out which note is sounding, from a signal that has no intention of saying.
- Pitch shiftingMoving a sound up or down in pitch without making it shorter or longer at the same time.
- PITR (Point-in-Time Recovery)The ability to restore a database to any moment you choose — for instance the second before someone ran DROP TABLE at 14:32.
- Pits and landsThe microscopic pits and flat lands a laser reads on an optical disc — the transitions, not the pit itself, carry the bits.
- PIVOT (SQL)An operation that turns rows into columns — e.g. turning a long table of (month, amount) into a wide one with a column per…
- Pivot pointThe point in an object about which it rotates, scales and is positioned — a sprite's zero point against its own texture.
- Pivotal SoftwareThe spin-off that gathered EMC's and VMware's loose open-source projects under one roof, went public, and was bought back…
- PixBrazil's central-bank-run instant payment system, which within a few years overtook both cards and cash by transaction count.
- PixarThe film studio that began as a hardware vendor and whose rendering software was an industry standard long before Toy Story.
- Pixel"Picture element" — the smallest addressable unit in a raster image or screen. Term coined ~1965 by Jet Propulsion Lab…
- Pixel artAn image built by hand one dot at a time, where every single pixel is a deliberate decision.
- Pixel PerfectRendering graphics with no antialiasing or interpolation, where every pixel sits exactly on integer boundaries — a…
- Pixel snappingRounding sprites and the camera to whole screen pixels before drawing, so pixel art does not shimmer, stretch or grow…
- Pixel-perfect collisionTwo sprites only count as colliding when at least one of their visible pixels actually overlaps one of the other's.
- PixelfedInstagram clone for the Fediverse — federated image feed with Stories, hashtags, collections. No algorithm.
- PixiJS2D rendering library — WebGL/WebGPU with Canvas2D fallback. Standard in HTML5-game scene. Goodboy Digital open-sourced 2013.
- Pixmap (X11)An image that lives inside the X server but is never shown directly — the invisible sibling of a window.
- PixrectSun's raster library of the 1980s: a "pixel rectangle" with an operations table, so the same code could draw into memory and…
- PJLHP's Printer Job Language — a layer above PCL and PostScript that controls the print job itself rather than the content of…
- PKCEProof Key for Code Exchange — OAuth extension (RFC 7636, 2015) that protects the authorization-code flow for public clients…
- PKCS #1PKCS #1 is the standard for RSA operations, and its padding has caused more confusion than RSA itself.
- PKCS #1 v1.5 paddingThe older RSA padding scheme that handed Bleichenbacher an oracle, and which still survives in systems where nobody has…
- PKCS #12PKCS #12 is the container format for private keys and certificates, protected by a password. You will meet it as .p12 or…
- PKCS#11A standard API, known as Cryptoki, that lets software ask an HSM or smart card to perform cryptography without the key ever…
- PKCS#5 paddingPadding scheme for 8-byte block ciphers, a narrower relative of PKCS#7 that shares a standard number with PBKDF2.
- PKCS#7 paddingA way to fill out the last block so that the original length can always be recovered.
- PKI (Public Key Infrastructure)The entire system around asymmetric key pairs — CAs, certificates, revocation, trust chains.
- PKT formatFidoNet's transport format: a file with a short header followed by a run of messages, the thing that actually moved between…
- PL1 / PL2 (power limits)Intel's power limits: PL1 is the long-term, sustainable consumption (roughly TDP) and PL2 is the higher short-term "boost"…
- Place and routeThe step that turns a logical netlist into actual geometry: where each cell sits on the silicon and how the wires between…
- PlaidThe invisible layer between American fintech apps and the banks: an API that lets Venmo and friends read your account.
- PlaintextThe message in readable form, before encryption, and the thing an attacker most wants to reach.
- Plan 9Bell Labs' successor to Unix, built by the same people, taking "everything is a file" all the way — and used by almost…
- Planar processJean Hoerni's trick of building transistors flat beneath a protective oxide layer — the foundation of every silicon chip…
- Planar reflectionExact reflections on a flat surface, made by mirroring the camera through the plane and rendering the scene a second time.
- PlanetScaleServerless MySQL built on Vitess — "git-style" schema branching, automatic sharding.
- PlanimeterAn instrument that measures the area of any shape by tracing a stylus round its outline — mechanical integration before…
- PlankalkülThe world's first high-level language, designed in an Alpine village by a man with no computer to run it on — and published…
- PlantUMLWrites UML diagrams as text. Alice -> Bob: Hello becomes a sequence diagram. Started in 2009 by Arnaud Roques and long the…
- Plasma effectThe billowing colour clouds made by summing sine waves and rotating the palette — cheap magic every demo coder wrote first.
- Plate reverbReverberation made by setting a suspended steel plate vibrating and recording how it rings out.
- PlatenThe hard roller behind the paper that hammers or the print head strike against — and that advances the sheet one line at a…
- PLATOA teaching system at the University of Illinois that, almost by accident, invented chat, forums, email and multiplayer games…
- PLATO NotesA bug-reporting tool on PLATO that turned into one of the world's first discussion forums.
- PlatterThe rigid, magnetically coated disc inside a hard drive that actually holds the data — a drive may stack one or several on a…
- Player killingKilling other players instead of monsters — the oldest and most stubborn argument in the MUD world.
- Player routineThe small assembly routine run once per frame to feed the sound chip — the reason a three-minute SID tune fits in a few…
- Player/missile graphicsAtari's own take on hardware sprites: narrow, screen-tall strips that move freely sideways and are collision-checked by the…
- Playfair cipherEncrypts letters in pairs using a keyword-filled 5×5 grid. Invented by Wheatstone, named after the friend who did the…
- PlayStationSony's revenge for a broken deal: the first console past a hundred million units, and the one that ended cartridges.
- PlaywrightThe E2E test tool from Microsoft — runs tests across Chromium, Firefox, and WebKit (Safari's engine) with the same API.
- PLC (Programmable Logic Controller)Industrial automation computer. Robust for factory environments. Programmed in graphical languages (Ladder Logic, Function…
- PleaseBazel-inspired build system — but written in Go, simpler setup, no JDK requirement. Born at Thought Machine 2017.
- PleromaLightweight Mastodon alternative. Elixir/Phoenix, built 2017. Lower resources per instance (3-4x more efficient than…
- Plessey codeOne of the oldest barcodes, devised by Britain's Plessey in 1971 and long seen on library shelves.
- PlextorJapanese optical drives that a generation of audio enthusiasts trusted for error-free ripping.
- PlexusWisconsin-based contract manufacturer focused on complicated products in small runs.
- PlistApple's configuration format: a nested dictionary of strings, numbers, dates and binary blobs, in three mutually…
- PlivoA voice and SMS API that began life as an open-source framework on top of the FreeSWITCH telephony engine.
- PlotlyCharts that are interactive from the outset — zoom, hover, toggle series — with bindings for Python, R and Julia.
- PLPMTUD (Packetization Layer PMTUD)Improved PMTUD that doesn't depend on ICMP messages. Uses TCP/UDP probes to solve the "ICMP blackhole" problem. RFC 4821.
- PlugboardThe program as a physical object: a board full of holes where the wires were the code.
- Plugin delay compensation (PDC)The DAW feature that delays every other track by as much as the slowest plugin, so the kick and the bass still land together.
- Plugin hostThe program that loads audio plugins, feeds them audio buffers and shows their interfaces — usually a DAW, sometimes a…
- PlumeFederated blog platform. ActivityPub-based. Rust, launched 2017. Users can follow blogs via Mastodon — a new post shows up…
- plwmThe Pointless Window Manager: written entirely in Python, and more a construction kit than a finished product.
- PMACA message authentication code built on a block cipher that can process blocks in parallel.
- PMODE/WA DOS extender from the demoscene that gave 32-bit programs the run of all memory — at a fraction of the size of the…
- PMUPerformance Monitoring Unit — CPU hardware that counts micro events: instructions retired, cache misses, branch…
- PNGLossless image compression with alpha channel. Designed 1996 as an open replacement for GIF (the Unisys LZW patent was…
- pnpm"Performant npm" — Zoltan Kochan, 2016. Uses symlinks and content-addressable storage so each package version is stored once…
- PocketBaseYour whole backend (SQLite + auth + file hosting + realtime + admin UI) in a single Go binary. Download. Run. Done.
- PodThe smallest unit in Kubernetes — one or more containers that share network and storage.
- Pod affinity / anti-affinityRules that control how pods are placed relative to EACH OTHER. Affinity draws pods to the same node/zone (e.g. an app near…
- Pod Disruption BudgetA Kubernetes object that guarantees at least N pods (or max M down) in a deployment remain available during planned…
- Pod Security StandardsKubernetes' built-in security levels for pods — Privileged, Baseline, and Restricted — that limit what a pod may do (run as…
- PodmanDocker-compatible container runtime with no daemon, runs rootless — Red Hat's answer to Docker's dockerd model.
- PoEPower and data down the same network cable — one run instead of two to every camera and access point.
- PoE+ (Power over Ethernet)Power over Ethernet — deliver both power and data over a single network cable. "PoE+" (802.3at) gives ~25 W, the original…
- Point (FidoNet)A user with their own FidoNet address under a host node — a full participant in the network without having to run a BBS.
- Point in polygonThe classic geometry test for whether a given point lies inside or outside a polygon.
- Point lightA light source that radiates equally in all directions from a single point, dimming with distance.
- Point-contact transistorThe first working transistor — two gold points on a sliver of germanium, demonstrated in December 1947.
- Point-in-time recoveryBeing able to restore a database to an arbitrary point in time, not just the most recent full backup. Requires continuous…
- PointerA variable that holds a memory address pointing to another variable.
- Poisson disk samplingGenerates points that are randomly spread yet never closer together than a given radius — an even "blue noise".
- POKEYAtari's 1979 chip that handled four-channel sound, the keyboard and serial I/O on one slab of silicon.
- Polar patternHow sensitive a microphone is to sound arriving from different angles, drawn as a polar plot.
- Polarity inversionFlipping a signal upside down — every sample multiplied by −1 — usually so two microphones stop cancelling each other.
- PolarsRust-built DataFrame — Ritchie Vink (Xomnia), 2020. Faster than pandas (5–30×), uses Apache Arrow natively and lazy…
- PolicerA mechanism that forces traffic under a rate limit by immediately dropping (or re-marking) packets that exceed the cap…
- Policy 4 (FidoNet)FidoNet's 1989 rulebook, which arranged the network into a hierarchy of coordinators and made it an offence to be…
- Policy routingChoosing a path on more than the packet's destination — source address, mark, incoming interface — by keeping several…
- Policy-based routing (PBR)Steering traffic based on criteria other than just the destination address — e.g. source address, application, or packet…
- Poly1305A fast message authentication code that Daniel J. Bernstein published in 2005.
- Polyalphabetic cipherA cipher that switches substitution alphabets through the text, so plain frequency analysis loses its grip.
- Polybius squareThe alphabet in a 5×5 grid so that each letter becomes a pair of numbers. Meant for torch signals, later reused in prison…
- PolyBLEPA cheap trick for making digital sawtooth and square waves free of aliasing.
- PolycomThe company behind the triangular speakerphone that sat in the middle of every meeting table for thirty years.
- PolyfillJavaScript code that adds new browser APIs to older browsers that lack them.
- Polygon meshThe standard way to represent a 3D shape in games: a set of vertices joined into faces, almost always triangles.
- Polygon mirrorThe spinning many-sided mirror that sweeps the laser beam across the drum inside a laser printer.
- Polygon soupA pile of triangles with no information about how they connect — no shared edges, no promise that the surface is closed.
- Polygraphic cipherA cipher that encrypts groups of letters rather than one letter at a time.
- PolymerGoogle's library that willed Web Components into existence by pretending browsers already supported them.
- Polymorphism"Same method name, different behaviour per type" — central in OOP.
- Polyphase filterA way of splitting an FIR filter into sub-filters so a sample rate converter only computes the samples it actually keeps.
- PolyphonyHow many notes an instrument can sound at once — counted in voices on a synth, each voice being a full chain of oscillator…
- PolyrepoMulti-repo strategy: each service/component has its own Git repo. Opposite: monorepo (everything in one). Polyrepo dominates…
- Polytopic cryptanalysisDifferential cryptanalysis with more than two plaintexts at a time, tracking the whole group's mutual differences through…
- POLYVALThe universal hash inside AES-GCM-SIV — GHASH in a mirror, with a bit order mortals can follow.
- PongTwo lines and a dot that created an industry — and a machine that stopped working because the coin box was full.
- POODLEA 2014 padding oracle attack that forced connections down to SSL 3.0 and recovered cookies one byte at a time.
- Pool allocatorAn allocator that divides a buffer into equal blocks linked in a free list and hands them out in any order in constant time.
- Poorvi VoraThe computer scientist who helped take a verifiable voting system from conference paper to a real municipal election.
- Pop-inWhen objects or textures snap into view instead of fading in, usually because they just crossed the draw distance or…
- POP3 (Post Office Protocol)Mail retrieval protocol. RFC 1939 (1996, v3 still the only relevant one). Default pattern: download mail to client, delete…
- PopeyeScans a cluster and reports everything that isn't an error but is going to hurt: missing probes, absent resource limits…
- Popover APINative HTML attribute for popovers — tooltips, menus, dialogs — without a line of JavaScript.
- PorkbunDomain registrar with a pig logo and an unusually flat price list.
- PortA "channel" on a server — a numbered entrance for a specific service.
- Port forwardingMap a port on your router to an internal computer — so the outside world can reach your local server.
- Port knockingThe firewall is closed by default — but if you "knock" on a specific sequence of ports, the SSH/admin port is temporarily…
- Port mirrorGeneric term for "send copy of port traffic to another port for monitoring". Cisco calls SPAN; Juniper calls mirroring…
- Port securityA switch feature that limits which MAC addresses can show up on a specific port — defence against MAC flooding and…
- Port-channelCisco term for an aggregated link: 2-8 physical ports bundled into one logical link. Bandwidth: N× single-port; redundancy…
- Porta cipherA polyalphabetic cipher from 1563 in which encrypting and decrypting are exactly the same operation.
- PortainerWeb GUI for Docker, Docker Swarm, Kubernetes and Nomad — Anthony Lapenna, 2016. "Cockpit for container hosts".
- PortalValve's first-person puzzle game from 2007, where you solve rooms by firing linked portals onto the walls.
- Portal cullingVisibility technique that carves a scene into rooms linked by portals and draws only what the camera can see through them.
- Portal renderingSplitting the world into rooms joined by "portals" in the doorways and rendering only through the portals the camera…
- PortamentoA smooth, continuous slide in pitch from one note to the next, rather than an instant jump.
- PortAudioA small C library offering one audio API on Windows, macOS and Linux and translating it to each system's drivers.
- PortFastA Spanning Tree feature that lets an access port go straight to "forwarding" instead of waiting out STP's listening and…
- Position-based dynamicsA physics method that solves constraints by nudging positions directly instead of integrating forces, trading physical…
- Positional encodingSince transformer attention doesn't know in what order tokens come, positional info must be injected explicitly — typically…
- POSIX (Portable Operating System Interface)IEEE standard defining the Unix API — file system semantics, processes, shell, command-line tools. Allows portable code…
- Post formatDifferent ways to post on social media: text, image, video, carousel (multi-image), link card, audio clip, poll. Platforms…
- Post-quantum cryptography (PQC)Encryption algorithms that withstand attacks from future quantum computers — RSA and ECC are not quantum-safe.
- Post–Turing machineEmil Post's 1936 model of computation: a worker moving between boxes in an infinite row, following a numbered list of…
- PostCSSCSS transformer via plugins. Andrey Sitnik, 2013. The basis for Autoprefixer, Tailwind CSS, CSS Modules, Vue scoped styles…
- PostGISA Postgres extension that adds geospatial datatypes, indexes, and functions — the de-facto standard for geo databases.
- PostgreSQLOpen-source relational database known for correctness, robustness, and extensibility. Traces back to Berkeley POSTGRES…
- PostgRESTWritten in Haskell — point it at a Postgres DB and it exposes the whole schema as a RESTful API. Filtering/joins/aggregates…
- PostHogAll-in-one open-source product analytics you can run on your own servers — analytics, session replay, feature flags and A/B…
- PostmanA graphical client for calling and testing APIs. Started in 2012 as a Chrome extension by Abhinav Asthana and became the…
- PostmarkTransactional email service built around receipts, password resets and other triggered mail that has to arrive quickly.
- PostmortemStructured review after an incident — what happened, why, what will we do differently next time?
- POSTNETThe US Postal Service barcode from the 1980s that encodes the ZIP code in tall and short bars for automated sorting.
- PostScriptAdobe's page description language from 1984, created by John Warnock and Chuck Geschke. A full stack-based programming…
- Potato attacksThe family of Windows techniques that convert SeImpersonatePrivilege into full SYSTEM. They have been called Hot, Rotten…
- Pouët.netThe demoscene's noticeboard — the database where every prod gets comments, thumbs and endless thread warfare.
- Poul-Henning KampDanish FreeBSD developer behind md5crypt, FreeBSD jails and the Varnish cache, and the man who gave us "bikeshed".
- Power analysisMeasuring a device's power consumption during a cryptographic operation to recover secret key bits.
- Power CartridgeA Dutch freezer cartridge for the C64/C128 that combined a fast loader, a monitor and a freeze button in one.
- Power gatingAn energy-saving technique that turns off the power ENTIRELY to parts of a circuit not being used — not just the clock. It…
- Power limit throttlingWhen a CPU/GPU clocks down because it hits its configured power limit (watt budget) rather than because it gets too hot. It…
- Power stateACPI-defined power states for CPU + system. C-states (CPU idle: C0 = active, C7+ = deep sleep), P-states (CPU performance…
- PowerEdgeDell's server line since 1994 — the workhorse of countless server rooms, whether it stands in a rack, a tower or as a blade.
- PowerPackerThe Amiga's ubiquitous file packer, whose .pp files and shared library let programs load compressed data without noticing.
- Powers-SamasThe Hollerith machine's only real competitor did the same job with no electricity at all, and still lasted into the 1960s.
- PowerStoreDell's 2020 midrange storage array that folded Compellent, Unity and VNX into a single line.
- PowerVaultDell's own entry-level storage — direct-attached enclosures and tape libraries beneath the pricier SAN lines.
- PPDA text file describing what a PostScript printer can do — trays, resolutions, fonts — so the driver knows what to ask for.
- PPG WaveWolfgang Palm's hybrid synth from Hamburg that turned wavetables into an instrument: digital oscillators, analogue filters.
- PPO (Proximal Policy Optimization)The standard RL algorithm for LLM training (the RLHF phase) — updates the policy "carefully" so it doesn't drift too far…
- PPPoE (PPP over Ethernet)The protocol that carried the dial-up login model into broadband. Standardized in RFC 2516 (1999) and still underlying many…
- PPQNPulses per quarter note — how many time steps a sequencer divides each beat into, and therefore how finely it can place a…
- PPU (NES)The NES graphics chip, Ricoh's 2C02 — a machine that draws tiles and sprites line by line and refuses to be interrupted…
- Pre databasePublic database that logs when, by whom and under what name a warez release was "pre'd".
- Pre-delayThe short gap between the dry signal and the start of the reverb – one knob that decides whether a voice stands in front of…
- Pre-echoThe faint smear of noise you can hear just before a sharp hit in compressed audio, where the codec has spread quantisation…
- Pre-trainingThe first, heavy training phase of an LLM — the model reads the entire internet and learns language.
- Preact SignalsFine-grained reactive primitives from the Preact team — signal(0), computed(), effect(). Inspired by SolidJS signals.
- PrecalcWorking out the expensive stuff ahead of time — sine tables, distance maps — so the real-time loop only reads ready values.
- Precision & RecallClassification metrics: precision = "when I say positive, how often am I right?". Recall = "did I find all the positives?".
- PreemptionThe kernel taking the CPU back from a process without asking — the opposite of waiting for it to yield voluntarily.
- PrefabA preconfigured template for a game object that you instantiate as many times as you like — edit the template and every copy…
- PrefectModern Python orchestration — Jeremiah Lowin (ex-Airflow contributor), 2018. "Negative engineering": focus on what has to be…
- prefers-reduced-motionA CSS media query that detects whether the user has asked their operating system to reduce motion/animations. It lets sites…
- Prefetch / PreloadHTML hints that ask the browser to fetch resources ahead of time before they're needed.
- PrefetcherA mechanism that predicts what data the CPU will soon need and fetches it into the cache in advance — before it's actually…
- Prefill / decodeThe two phases of LLM inference: prefill processes the whole prompt in parallel (filling the KV cache), and decode generates…
- Prefix cachingKeeping the KV cache for a prompt segment that many requests share, instead of recomputing the same system prompt ten…
- Prefix-listA filter that matches network prefixes (with the ability to specify an exact prefix length or a range) to decide which…
- Preimage attackAn attack that tries to find a message producing a given hash value.
- preload / prefetchResource hints (<link rel>) that tell the browser to fetch resources in advance. preload fetches something needed soon on…
- Premultiplied alphaStoring colour already multiplied by its alpha value, rather than alongside it — which makes compositing mathematically…
- Prepared statementSQL pattern: send a query template with placeholders ($1, ?), bind parameters separately. Two main wins: protection against…
- PresarioCompaq's consumer brand from 1993 — the home PC meant to carry the corporate heavyweight into the living room.
- PRESCRIBEKyocera's page description language, embedded in the print stream and recognisable by its opening "!R!" sequence.
- PresenceOnline-status info in chat protocols: available, away, busy, do-not-disturb, offline. XMPP made presence a first-class…
- PRESENTAn ultra-lightweight block cipher from 2007, made for RFID tags and sensors and standardised in ISO/IEC 29192-2.
- Present extension (X11)The X extension that lets a client say "show this pixmap in this window at the next frame" and be told when it actually…
- Presentation ManagerThe graphical windowing system of OS/2, built jointly by IBM and Microsoft — and the source of Windows 3's look.
- Preshifted spriteStoring a sprite as several ready-shifted copies, one for each pixel offset within a byte, so the drawing routine never has…
- PrestelThe world's first public videotex service, best remembered for the break-in that gave Britain its first computer crime law.
- PrestoDistributed SQL query engine — Facebook, 2012, to replace Hive on MapReduce with interactive queries. Forked to Trino in…
- PrettierOpinionated code formatter. JavaScript, TypeScript, CSS, JSON, Markdown, YAML, GraphQL etc. James Long, 2017. "End all style…
- PRF (pseudorandom function)A keyed function that cannot be told apart from a truly random function by an attacker with bounded computing power.
- PRG fileCommodore's simplest program file: two bytes of load address, then raw bytes straight into memory.
- PRG-ROMA cartridge's program memory — the code and game data the CPU runs, kept apart from the graphics' own ROM.
- Primary account number (PAN)The 15 to 19 digits on the front of a card, structured enough to give away both the issuer and your typos.
- Primary keyColumn (or combination) that uniquely identifies every row in a table.
- Prime ComputerThe minicomputer maker whose 32-bit superminis and PRIMOS operating system filled the gap between the mainframe and the PC.
- Primitive restartA reserved index value that breaks a triangle strip mid-stream and starts a new one, so a single draw call can hold many…
- Print hammerThe solenoid-driven hammer in an impact printer that strikes paper and ribbon against the right letter at the instant it…
- Print headThe moving part of a printer that actually lays the ink or strikes the character onto the paper.
- Print serverThe middleman that accepts print jobs from everyone on the network and queues them for the right printer.
- Print spoolerA system service that accepts print jobs, buffers them on disk and feeds the printer at its own pace so the program need not…
- Print-throughThe field from a strongly recorded layer of wound tape prints a faint ghost onto the neighbouring wrap — heard as a pre- or…
- Printer MIBThe SNMP object tree that lets any monitoring station ask any printer how much toner is left.
- Printer ribbonAn ink-soaked fabric strip that impact printers and typewriters strike against to transfer ink onto the paper.
- PrintNightmareCVE-2021-34527 — RCE + LPE in Windows Print Spooler. Accidentally leaked by researchers before Microsoft patched it.
- Priority hints (fetchpriority)The fetchpriority attribute (high/low/auto) that lets you control how the browser prioritizes the download of a specific…
- PrismaTypeScript-first ORM — you describe the schema in schema.prisma, Prisma generates a type-safe client where every query…
- Prismatic jointA joint that allows sliding along a single axis only — the mirror image of the hinge, which allows only rotation.
- PrismicFrench headless CMS that introduced "Slice Machine" — developers define reusable components, marketers drag-drop them as…
- Private IPIP addresses reserved for internal networks — they can't be reached on the internet.
- Private keyOne half of an asymmetric key pair — the one you never share with anyone.
- Private Network AccessBrowser security mechanism that blocks public web pages from talking to private IP addresses (router 192.168.x, localhost…
- Private VLAN (PVLAN)A technique that isolates hosts from each other within the same VLAN and subnet — they share the network and gateway but…
- Privilege escalationWhen an attacker with limited access exploits a vulnerability to gain higher privileges.
- PRM (Process Reward Model)A reward model that judges each step of a chain of reasoning, not just whether the final answer was right. Catches the model…
- PRMLThe read channel that computes the most likely sequence of bits instead of hunting for peaks — letting the hard disk pack…
- Pro ToolsThe DAW that became the recording studio's shared language — to the point where "send me the Pro Tools session" still just…
- Probabilistic neutral bitsKey bits that barely affect a measurable bias, and which the attacker can therefore skip guessing.
- ProBoardBelgian DOS BBS software from the early 90s, popular in Europe with sysops who wanted RemoteAccess compatibility without…
- Procedural animationMotion computed at runtime from rules or physics instead of played back from keyframes — how a lizard's feet find uneven…
- Procedural generationCreating content — levels, terrain, textures — with algorithms at build or run time instead of placing every element by hand.
- ProcessA running instance of a program — gets its own memory, its own PID, can contain many threads.
- Process nodeThe designation of a chip manufacturing process, traditionally given in nanometers ("5 nm", "3 nm"). Nowadays the number is…
- procfsThe virtual filesystem under /proc where the kernel exposes processes and state as readable files.
- procmailThe Unix program that sorted incoming mail with regular expressions, in a configuration language nobody quite managed to…
- Procomm PlusThe terminal program that started as shareware from Missouri and ended up as a Symantec product in corporate modem pools.
- ProdigyIBM and Sears' graphical online service funded by advertising — which learned that users want to talk to each other, not…
- Product cipherA cipher that chains several simple steps, typically substitution and transposition, in successive rounds.
- Product-Market Fit (PMF)When a product solves a real need for a specific market so well that growth "pulls itself". The term was coined by Andy…
- PROFINETIndustrial Ethernet protocol developed by Siemens — drives factory floors worldwide. Real-time extensions go down to 31 µs…
- Program Change (MIDI)The MIDI message that tells a synth to switch sounds — two bytes long, and the source of one of MIDI's most durable…
- Program ManagerThe Windows 3.x shell: a window full of program groups with icons, which replaced the file list of MS-DOS Executive in 1990…
- Program of Thoughts (PoT)LLM generates code (Python) instead of natural-language reasoning — the code is executed, the result is the answer. Better…
- Programmable VoiceTwilio's original product: a cloud API that lets code place, answer and steer phone calls without the developer ever…
- Progress SoftwareThe company behind the OpenEdge fourth-generation language, which reached a much wider audience when its MOVEit file…
- Progressive deliveryAn evolution of continuous delivery where new versions are rolled out gradually to ever-larger portions of users, with…
- Progressive meshA base mesh plus an ordered list of vertex splits, replayed forward or backward to give continuous level of detail.
- Progressive scanEach frame transmitted complete, line by line — the opposite of interlacing, and what the p in 1080p stands for.
- Project AthenaMIT's 1983 campus computing project, meant to put workstations in front of students, which shipped Kerberos, X and Zephyr to…
- Project Looking GlassSun's three-dimensional Java desktop from 2003, where you could flip a window over and write notes on its back.
- Projectile weaponA weapon whose shot is an object in its own right, with velocity and a trajectory, travelling through the world tick by tick…
- ProjectorThrows the image onto an external surface instead of owning it itself. Three dominant technologies: DLP, LCD, LCoS.
- ProlexicA DDoS protection service that started by rescuing online bookmakers from extortionists and ended up inside Akamai.
- ProLiantThe server family Compaq launched in 1993 and that is now HPE's workhorse in the server room.
- PrologLogic programming language from 1972 (Alain Colmerauer, Marseille). Describe the world as facts + rules, then query — the…
- PrometheusOpen source system for metrics — pulls numbers from endpoints and stores them in a time-series database.
- Prometheus exporterAn adapter that exposes metrics from a system in Prometheus text format (/metrics endpoint). Prometheus scrapes these…
- PromiseA JS object that represents a future value — like a receipt you take and later cash in once the food is ready.
- PromptThe input you give an LLM — the question, instruction or context.
- Prompt cachingA feature where an LLM provider caches the processing of a recurring prompt prefix (e.g. a long system prompt or a…
- Prompt engineeringThe craft of writing prompts so the LLM delivers what you actually want.
- Prompt injectionAn attack on an LLM where the user sneaks in instructions that override the system prompt.
- PromptuaryNapier's least-known invention: perforated slats that multiplied multi-digit numbers in one pass, more capable than his…
- Proof of StakeConsensus where the right to create blocks is allocated by how much capital you have locked up, not by how much electricity…
- Proof of Work (PoW)Require costly computation before an action is accepted — making spam/abuse economically unreasonable.
- ProofpointThe email security company that built a multi-billion-dollar business on the fact that people still click links.
- PropertiesJava format for key-value config files (.properties). Text-based, one pair per line: key=value. Standard format for Java app…
- Property (X11)Named blocks of data the X server stores on a window for anyone who cares to read them — the notice board that window…
- Property-based testingYou write invariants (properties that should hold for every input) — the library generates hundreds of random inputs and…
- PropertyNotifyThe X11 event reporting that a property on a window has changed or been deleted — and, by accident, the only way to ask the…
- Prophet-5The first polyphonic synth that remembered its sounds — a microprocessor made patch sheets and pencil sketches obsolete.
- Proportional compass (sector)Two graduated rulers on a hinge that solved proportions, root extraction and gunnery problems with the help of an ordinary…
- Proposed Electronic CalculatorAlan Turing's 1945 computer design: a report describing a machine so stripped down that almost everything had to be done in…
- Proprietary softwareSoftware where source code isn't public + the license restricts use. Opposite: open source. Classic examples: Windows…
- ProseMirrorA toolkit for rich text editing by Marijn Haverbeke (2016). Not a finished editor — a document model library you build an…
- ProsperoA virtual file system for the whole internet that, in practice, became the protocol you used to talk to Archie.
- Protection ringsThe processor's hierarchy of privilege levels, where ring 0 gets everything and ring 3 almost nothing.
- ProtocolRules for how two parties should communicate — message format, ordering, error handling, state transitions. TCP, HTTP, SMTP…
- Protocol Buffers (Protobuf)Google's binary serialization format. Schema-based (.proto files), compiles to code in many languages. Standard in gRPC +…
- Proton MailSwiss end-to-end encrypted email — founded by CERN physicists, funded via crowdfunding and subscriptions. No ads, no…
- Prototype pollutionJavaScript vulnerability — an attacker modifies Object.prototype, which affects every object in the app.
- ProTrackerThe Amiga's definitive MOD tracker — four channels, thirty-one samples, and the grid that shaped a generation's sound.
- Provisioning profileThe file tying together app ID, signing certificate and permitted devices — and the thing iOS developers have a famous…
- Proximity effectThe closer a directional microphone gets to the source, the more bass it picks up.
- Proxmox VEA Debian-based virtualization platform with a web interface. Runs both full virtual machines via KVM and lightweight…
- ProxyIntermediary that forwards network traffic between client and server.
- Proxy ARPWhen a router answers ARP requests on behalf of another host — it gives its own MAC for an IP that actually lives in a…
- ProxyLogonCVE-2021-26855 + 3 chained bugs — pre-auth RCE in Microsoft Exchange Server. Hafnium (Chinese APT) exploited at scale before…
- ProxySQLA proxy that speaks the MySQL protocol and sits between the application and the database. The application thinks it is…
- PRP/PRF switching lemmaThe result that lets a proof pretend a block cipher is a random function, at a cost that grows with the square of the number…
- PSD2The EU's second Payment Services Directive, which forced banks to let third parties in through APIs and introduced strong…
- Pseudo-3D (2.5D)The umbrella name for every trick that fakes three dimensions in an engine that really only draws in two.
- Pseudo-transparencyThe trick that gave X terminals a see-through background before Composite: paint the piece of wallpaper behind the window as…
- PseudocodeCode-like description of an algorithm without committing to a specific language.
- Pseudorandom number generator (PRNG)A deterministic algorithm that produces a sequence that looks random but can be reproduced from its seed.
- Pseudorandom permutation (PRP)A permutation that an adversary with limited access cannot tell apart from a random permutation.
- psh (NeWS)The NeWS PostScript shell: a program that wired your terminal's stdin to the window server, so you could type PostScript…
- PSIDThe file format that packs a C64 tune as tiny machine code and lets an emulator play it back on any computer.
- PSINetOne of the first commercial internet providers, and one of the dot-com era's more spectacular collapses.
- PsionThe London firm that built the handheld computer before the word PDA existed, and whose operating system became the basis of…
- PsiQuantumThe quantum company that skipped the small demo machines and aimed straight for a million qubits.
- PSOLAPitch-Synchronous Overlap-Add: a time-domain method that changes the pitch or duration of speech by cutting out and…
- PSS (Probabilistic Signature Scheme)An RSA signature scheme that adds a random salt to every signature, and the variant TLS 1.3 requires for RSA signatures.
- PSU (Power Supply Unit)The computer's power supply — converts mains AC to lower DC voltages for the motherboard, CPU, GPU.
- pswrapAdobe's preprocessor that turns snippets of PostScript into C functions, so programs could draw with Display PostScript…
- PsychoacousticsThe study of how sound is perceived rather than how it is measured — and the reason an MP3 can throw away most of the audio…
- PsygnosisThe Liverpool publisher with the owl logo that sold the Amiga on its looks and then became Sony's PlayStation studio.
- PTCThe company that made parametric 3D modelling the industry standard with Pro/ENGINEER.
- PTP (Precision Time Protocol)The protocol that keeps clocks on a local network in step to well under a microsecond, and the quiet foundation beneath…
- PTW attackThe 2007 attack that recovered a 104-bit WEP key in under a minute from a few tens of thousands of captured packets.
- Pub-sub (Publish-Subscribe)Messaging pattern where publishers send messages to a "topic" without knowing which subscribers are listening. Loose…
- Public channelOne-to-many broadcast in a chat app: owner/admins post, subscribers read (no replies). Telegram popularized it (2015)…
- Public IPAn IP address visible and reachable from the internet — as opposed to a private IP behind a router/NAT.
- Public keyOne half of an asymmetric key pair — meant to (and supposed to) be shared openly.
- Public Suffix ListMozilla-maintained list of "effective TLDs" — domains under which websites can be registered directly. Includes .com +…
- PubNubAmerican realtime service that markets itself as a global "Data Stream Network" for pub/sub in apps and IoT.
- PubstroA warez storage point raised on someone else's hacked server — the scene's way of getting free bandwidth and not having to…
- PucrunchA 1997 LZ77-plus-RLE hybrid whose open write-up taught a whole generation how crunching actually works.
- Pueblo (MUD client)A mid-1990s attempt to give text worlds pictures, sound and 3D by letting the server send HTML.
- PUF (Physically Unclonable Function)A circuit deriving a unique key from the silicon's own manufacturing variation rather than storing it anywhere. The key…
- PugTemplating engine for Node.js. Originally "Jade" (TJ Holowaychuk, 2010), renamed 2016 (trademark conflict)…
- Pull request (PR / MR)A request to merge changes from a git branch into another, usually with code review.
- Pull secretA Kubernetes secret with registry credentials so pods can pull images from private registries (GHCR, ECR, GitLab, Harbor)…
- Pulley jointA joint that links two bodies over imaginary pulleys so that when one descends, the other rises.
- Pulse Width ModulationA technique for simulating analog signals by varying the width of digital pulses, fundamental to chiptune synthesis for…
- PulseAudioThe sound server that gave the Linux desktop per-application volume and audio that follows you to your headphones — after…
- PulumiIaC with real programming languages — Joe Duffy (ex-Microsoft Midori), 2017. Define AWS/Azure/GCP resources in TypeScript…
- Punch cardThe data medium that gave us 80 characters per line — a limit still present in coding standards written by people who never…
- Punch card readerA device that fed programs and data into a computer by sensing the holes in stacks of punched cards.
- Punch-inDropping into record partway through a track that is already playing, so that only the botched passage is replaced and the…
- Punter protocolThe Commodore world's answer to XMODEM: a modem file transfer protocol that became the standard on C64 bulletin boards in…
- PuppetConfiguration management — Luke Kanies, 2005 (now Perforce). Define the desired end state in a Puppet DSL; agents converge…
- PuppeteerA Node.js library that drives headless Chromium via the Chrome DevTools Protocol. Generate PDFs, screenshots, scraping…
- Pure DataThe Max creator's second attempt: the same boxes and cables, but free, plain-looking and built to be embedded.
- Pure functionA function that always returns the same output for the same input and has no side effects.
- Pure StorageThe storage company that bet on flash replacing spinning disks in the data centre — before the price really justified it.
- PurismAn American company selling laptops and phones with physical switches for the camera, microphone and radios.
- PURPLEJapan's diplomatic cipher machine of 1939, built from telephone-exchange relays instead of rotors — and reconstructed by the…
- Purple MotionJonne Valtonen's handle in Future Crew — the man behind much of Second Reality's music, later an orchestral composer.
- Purple teamA collaboration where the offensive "red team" (attackers) and the defensive "blue team" (defenders) work TOGETHER in real…
- Push notificationA message the server sends to the device without the app asking — the opposite of the app polling.
- PushboxThe collision box that stops two characters from standing on the exact same spot — the thing that shoves them apart when…
- PusherBritish realtime platform whose hosted WebSocket API let web apps push live updates without running their own server…
- Pushpin (OPEN LOOK)OPEN LOOK's answer to menus and dialogs that vanish too soon: a drawn pushpin in the corner, and one click on it keeps the…
- PVC (PersistentVolumeClaim)Kubernetes' way of asking for storage. A pod doesn't mount a disk directly; it claims "20 GB of this storage class", and the…
- PVS (potentially visible set)A precomputed table of which parts of a static world can be seen from each other part — expensive to bake, nearly free to…
- PWA (Progressive Web App)A website that behaves like a native app — installable, works offline, can send notifications.
- PWM (pulse-width modulation)Pulse-Width Modulation — controlling power by rapidly switching a signal on and off, where the fraction of "on" time (duty…
- pwm (window manager)The window manager that invented tabbed frames: several programs in one window frame with a row of tabs on top, long before…
- PwnKitCVE-2021-4034 — pkexec (polkit) bug. argv[0] = NULL ⇒ root via environment variable manipulation. 12 years old at disclosure.
- PyCharmJetBrains' Python IDE — heavy, slow to start, and still the best in class at refactoring.
- PygameA Python library on top of SDL for writing 2D games — and for a whole generation, the first brush with game programming.
- Pyramid TechnologyA Californian company that shipped one of the first commercial RISC machines, and settled the Unix wars by simply running…
- PySparkThe Python API for Apache Spark — all Spark functionality (DataFrame, Spark SQL, MLlib, Structured Streaming) available from…
- pytestPython's de-facto standard test runner — minimal syntax, powerful fixtures, parametrize. Pushed unittest from the standard…
- PythonGuido van Rossum, 1991 — "the monolingualism of legibility". The world's most popular language per TIOBE/Stack Overflow…
- PyTorchThe dominant deep learning framework — Pythonic, dynamic graph, loved by researchers.
Q
- Meta Quest 3Standalone VR headset from Meta — colour passthrough for mixed reality, no external computer required. $499.
- Q factorA measure of how narrow a filter is: the centre frequency divided by the bandwidth between the −3 dB points.
- Q-in-Q (802.1ad)Putting a VLAN tag outside the customer's own VLAN tag, so a carrier can transport a customer's entire VLAN space without…
- QAMThe modulation that packs several bits into each symbol by varying both amplitude and phase.
- QAOAA hybrid algorithm for combinatorial optimisation — the quantum computer proposes, a classical optimiser adjusts, and round…
- QdrantVector database written in Rust — open source, fast, one of the top picks for RAG pipelines.
- QEMUFree machine emulator that can both simulate foreign processor architectures and, paired with KVM, run virtual machines at…
- QICThe quarter-inch tape that handled PC backup through the 1980s and 90s, often through the same connector as the floppy drive.
- QimondaInfineon's spun-off DRAM maker, which managed an IPO and an insolvency in under three years.
- QiskitIBM's Python framework for quantum programming, and the one more people have tried than any other — largely thanks to free…
- QLCQuad-Level Cell — NAND flash with 4 bits per cell (16 voltage levels). Densest + cheapest NAND, but endurance ~1000 erase…
- QLC NANDQuad-Level Cell — NAND flash that stores 4 bits per cell. Gives the cheapest storage per gigabyte and the highest density…
- QLED (Quantum Dot LED)LCD displays with a quantum dot layer for better colour — Samsung's marketing name, not a separate display technology like…
- QlikThe BI company from Lund, Sweden, whose software shows not only what you selected but everything you thereby excluded.
- QLogicThe Emulex spin-off that became its parent's fiercest competitor in server storage adapters.
- QLoRAQuantized LoRA — a technique (2023) that makes it possible to fine-tune very large models on a single consumer GPU by…
- QMLQt's declarative UI language: a JSON-like tree in which any property can be a JavaScript expression that re-evaluates itself.
- QmodemA fast DOS terminal program from a one-man company named after a computer-takeover film, later bought by the makers of…
- QNAPSynology's perennial rival in the NAS market — powerful and feature-stuffed, but notorious for the ransomware waves that hit…
- QNXCommercial microkernel real-time operating system, now pervasive in car infotainment and safety systems.
- QorvoThe radio-frequency firm formed in 2015 when RF Micro Devices and TriQuint merged.
- QoS (Quality of Service)Prioritising certain network traffic over others — e.g. Zoom calls over torrent downloads.
- QoS / DiffServQuality of Service via DiffServ (Differentiated Services) — mark packets with a DSCP code in the IP header so routers can…
- QoS class (K8s)The quality class Kubernetes assigns a pod based on how its resource requests and limits are set. The class determines which…
- QoS policerQoS mechanism: hard rate-limit. Traffic over limit is dropped (or marked down). Token-bucket algorithm. Standard use…
- QoS shaperQoS mechanism: smooth out traffic by buffering and delaying instead of dropping. Output rate capped at target — bursts…
- QOTDQuote of the Day: a service on port 17 that answers with a short quotation and hangs up.
- QR codeTwo-dimensional barcode that stores data in a grid of squares and reads equally fast from any angle.
- QtCross-platform C++ framework for graphical interfaces — and rather more besides.
- Qt CreatorOfficial IDE for Qt development (C++ + QML). Built on Clang for intelligence. Cross-platform: Windows, macOS, Linux.
- Qt/EmbeddedTrolltech's 2000 edition of Qt that drew straight into the Linux framebuffer through its own small window system, QWS, and…
- QtileA tiling window manager written and configured in Python, with a built-in status bar and, since 2021, a Wayland backend as…
- Quadric error metrics (QEM)The error metric that drives mesh simplification: each vertex carries a quadric measuring how far a collapse would move the…
- Quadro (now RTX A/Ada)Nvidia's workstation GPU line for CAD, 3D rendering, CGI. Rebranded 2021 from "Quadro" to "RTX A series" and 2023 to "RTX…
- QuadtreeThe octree's two-dimensional sibling — it divides a plane into four quadrants over and over to avoid testing everything…
- Quagmire cipherQuagmire is a family of polyalphabetic ciphers in which a keyed alphabet replaces the standard one in one or both rows.
- QuakeThe first game with a genuinely three-dimensional world and internet play — and therefore the technical foundation of all…
- QuakeCThe C-like language Quake's game logic was written in, which more or less created the modding scene as a side effect.
- QuakeNetThe IRC network that began as a hangout for Quake players and grew into one of the largest anywhere.
- QualcommOwns a large share of the patents mobile networks are built on — and charges every phone maker regardless of whose chips…
- QualysVulnerability scanning as a hosted service well before anyone called it SaaS — plus a research team that finds bugs in…
- Quanta ComputerThe world's largest laptop maker, from which no consumer has ever bought a laptop.
- QuantinuumThe unlikely result of a thermostat maker and a British software startup pooling their quantum ambitions.
- QuantizationShrink an ML model by storing weights in fewer bits — 32-bit floats → 8-bit ints, or even 4-bit.
- Quantization (LLM)Storing a model's weights at lower numerical precision (e.g. 4 or 8 bits instead of 16) to reduce the memory need and speed…
- Quantization (MIDI)Snapping recorded notes to the nearest line of a time grid, so slightly loose playing lands exactly on the beat.
- Quantization-Aware Training (QAT)Trains the model knowing it will run quantised (INT8/INT4) — fake-quantize forward, full-precision backward. Loses much less…
- Quantum annealingFinding an optimisation problem's best solution by letting a quantum system settle into its lowest energy state.
- Quantum circuitThe standard way of describing a quantum program: qubits as horizontal lines, gates as boxes, measurement at the far right.
- Quantum computingA machine that computes with quantum states rather than bits — faster on a handful of problems, slower on everything else.
- Quantum CorporationThe storage company that started in hard drives, handed them to a rival, and remade itself as the home of tape.
- Quantum cryptanalysisAttacking cryptography with quantum algorithms, which demolishes today's public-key systems but mostly just chafes the…
- Quantum entanglementWhen several particles share a state that cannot be described separately — the resource that makes quantum computers more…
- Quantum error correctionProtecting quantum information from noise without looking at it — the precondition for quantum computers becoming useful.
- Quantum Fourier transformThe counterpart to the FFT but on a quantum register — exponentially faster, though the result cannot be read out.
- Quantum gateThe basic operation in a quantum computer — a rotation of the qubits' state, and unlike classical gates always reversible.
- Quantum key distributionAgreeing on an encryption key with security grounded in physics rather than in mathematical difficulty.
- Quantum LinkA Commodore 64 online service launched in 1985 by the company that later renamed itself America Online.
- Quantum simulatorAn ordinary program computing what a quantum computer would have done — indispensable for development, and hopeless beyond…
- Quantum supremacyThe point where a quantum computer does something no classical computer can keep up with — reached in 2019, on a task with…
- Quantum teleportationMoving a qubit's state to another qubit elsewhere — without sending the qubit, and without exceeding the speed of light.
- Quantum volumeIBM's metric that folds in both qubit count and qubit quality — an attempt to make comparisons between machines meaningful.
- QuarkusRed Hat's attempt to make Java suitable for containers by moving as much work as possible from startup to build time.
- QuarterdeckA company that lived off DOS not having enough memory, and died at roughly the moment that stopped being true.
- Quartz CompositorThe Mac OS X window server that since 2001 has given every window its own buffer and composed the screen from them: the…
- QuaternionFour numbers that describe a rotation in three dimensions without locking up, and that interpolate smoothly between…
- Qubes OSA desktop operating system that assumes something will get compromised, and so carves the machine into isolated virtual…
- QubitThe quantum computer's smallest unit — can be zero, one, or a combination of both right up until it is measured.
- QueryA request to the database — SELECT, INSERT, UPDATE, DELETE.
- Query expansion (AI)Expanding or rephrasing the user's query before retrieval, to catch more relevant documents. An LLM generates synonyms…
- Query plannerDB component that takes a SQL query and decides the physical execution plan: which indexes to use, join order, join…
- QueryPointer“Where is the mouse right now?” in X protocol form — with a reply, and therefore a full round trip to the server.
- QueryTreeThe X11 request that tells you where a window sits in the tree: its root, its parent and every one of its children.
- Quest SoftwareCalifornian company behind Toad, the tool a generation of Oracle developers kept open all day.
- QuestDBTime-series database with Postgres wire and SQL — designed for financial tick data and IoT. Tracking data + InfluxDB Line…
- QueueFIFO data structure — "First In, First Out". First in, first out.
- QUICModern transport over UDP — the basis for HTTP/3, faster handshake and better under packet loss than TCP.
- QUIC datagramA QUIC extension (RFC 9221) for unreliable datagrams — messages that aren't retransmitted on loss, on top of an encrypted…
- QuickBBSA late-1980s DOS bulletin board that was fast and easy to set up, and spawned so many clones that its file formats outlived…
- QuickDrawBill Atkinson's graphics library in the Macintosh ROM, whose regions made overlapping windows feasible on an 8 MHz 68000.
- QuicksortPick an element, push everything smaller to its left and everything larger to its right, then repeat on both halves.
- Quiet zoneThe mandatory blank margin before and after a barcode that lets a scanner find where the code begins and ends.
- QuipuKnotted, coloured cords the Andean empires used to keep tax, census and storehouse records — data stored in string rather…
- QumeThe daisy wheel printer maker founded by an engineer from Diablo in order to compete with Diablo.
- QuorumThe number of replicas that must respond to an operation for it to count — typically a majority (N/2 + 1) to ensure readers…
- Quorum (N/R/W)Voting across replicas — each write needs ack from W nodes, each read queries R nodes. If R + W > N you're guaranteed to…
- Quorum readThe technique of reading from (and writing to) enough replicas to guarantee you see the latest value, via the rule W + R >…
- Quote postRe-share of another user's post with your own comment. Twitter launched in 2015 as "Quote Tweet". Subtly different from…
- Quote-post (Bluesky)A Bluesky feature for quoting a post with your own comment — but with controls Twitter lacks: you can detach your post from…
- Quote-tweetTwitter/X feature: retweet with your own comment above the quoted post. Introduced 2015. Dual use: share with added context…
- qvwmAn X window manager that imitated Windows 95 down to the pixel, taskbar, Start menu and keyboard shortcuts included.
- QwenAlibaba Cloud's open-weights model family — among the strongest non-frontier models of 2024–2025, ranging from 0.5B to 235B…
- QwikMisko Hevery (the Angular creator) framework that replaces hydration with "resumability" — the app "wakes" from server state…
- Qwik City"Next.js for Qwik" — file-system routing, server functions, middleware, edge deployment on top of Qwik's resumability.
- Qwik resumabilityQwik's innovation: no hydration. The page serialises with all event state baked in ⇒ client "continues" from where the…
- QWKAn offline mail packet for BBSes — download all the new messages, read and reply without the connection's ticking meter.
R
- C++ rangesC++20's overhaul of the standard algorithms: a collection is passed as one object instead of two iterators, and…
- RProgramming language for statistics + data analysis. Ross Ihaka + Robert Gentleman, University of Auckland, 1993…
- RabbitA fast stream cipher from 2003 with a 128-bit key and a 64-bit IV, which advanced to the eSTREAM project.
- RabbitMQOpen-source message broker — AMQP-based, built in Erlang for fault tolerance. Standard message queue in many stacks.
- Raccoon attackA timing attack on TLS 1.2 and earlier, where leading zero bytes of the Diffie-Hellman secret are stripped before key…
- Race conditionA bug that surfaces when two threads/processes "race" each other and the result depends on who gets there first.
- Race condition / TOCTOUA vulnerability where state changes between when a program CHECKS something and USES it (Time-Of-Check to Time-Of-Use). The…
- Race-to-idleAn energy strategy where the processor runs a task as fast as possible to finish quickly and then go into a deep…
- Rachel TobacAmerican social engineer who demonstrates, preferably on camera, how few phone calls it takes to take over someone's…
- Racing the beamSynchronising the processor to the exact position of the electron beam, changing graphics registers line by line as the…
- Rack ExtensionReason's own sandboxed plugin format, invented to avoid opening the door to VST.
- Rack unit (U)The height measure for equipment in a 19-inch rack. 1U is exactly 44.45 mm (1.75 inches). A typical server is 1U or 2U; a…
- RacketModern Scheme dialect. Matthew Flatt + PLT team, 1994 (then "PLT Scheme", renamed 2010). Famous for its macro system…
- RackspaceA hosting company that sold human support in an industry busy automating it away.
- Radia PerlmanSolved the problem of loops in bridged networks with an algorithm she wrote in a day — and summarised it in a poem.
- Radial blurA blur that smears every pixel toward or away from a centre point so the image seems to stream out in shafts of light — the…
- RadioShackThe electronics chain with drawers full of resistors and cables that once sold one of the first home computers.
- RadiosityA global-illumination method that solves how diffuse light bounces between surfaces by computing the energy exchange among…
- RADIUSAAA protocol (Authentication, Authorization, Accounting) — central user database for network devices (Wi-Fi APs, switches…
- Radix UIHeadless React component library — accessibility + behavior, no styling. Build on top with Tailwind or your own CSS. WorkOS…
- RadixAttentionSGLang's way of reusing KV cache across requests by keeping every prefix it has seen in a radix tree instead of throwing the…
- RadwareAn Israeli maker of load balancers and DDoS protection that picked up one of the industry's oldest product lines from a…
- Rafail OstrovskyThe UCLA cryptographer who, with Goldreich, invented oblivious RAM — memory where even the access pattern gives nothing away.
- Rafał WojtczukPolish low-level researcher who, together with Joanna Rutkowska, showed that most of what sits beneath the operating system…
- RaftDistributed consensus algorithm — gets multiple nodes to agree on which writes happened, in what order.
- RAG (Retrieval-Augmented Generation)The technique where an AI first searches a knowledge base, then formulates the answer based on what it found.
- RAG (Retrieval-Augmented Generation)The technique of fetching relevant documents from a knowledge base and inserting them into an LLM's context before it…
- RAG pipelineThe full chain from document to answer: ingest (parse + chunk) → embed → store in vector DB → query: retrieve → optionally…
- RAGASThe most popular open-source eval framework for RAG — metrics like faithfulness, answer relevancy, context recall, context…
- RagdollPhysics-driven character animation in which a limp body is simulated as linked rigid bodies rather than played from a canned…
- Ragdoll blendingThe transition between a physics-driven ragdoll and regular animation — usually in the hard direction, when a knocked-down…
- RAGE (Rockstar Advanced Game Engine)Rockstar's own engine, built when RenderWare vanished — and the backbone of every GTA and Red Dead since.
- Rage baitContent deliberately designed to make people angry, so they reply, quote, and share in anger — which the algorithm reads as…
- RAID (Redundant Array of Independent Disks)Combine multiple disks for speed, redundancy, or both.
- RAID 0Striping without redundancy: data split across N disks, each row write split. Throughput Nx. ZERO failure protection: one…
- RAID 10RAID 1+0: pairs of mirrors striped. 4+ disks, half capacity used. Best balance of performance + redundancy + rebuild time…
- RAID 50Nested RAID: pairs of RAID 5 arrays striped together. Min 6 disks. Better rebuild time + write performance than plain RAID…
- RAII (Resource Acquisition Is Initialization)C++ pattern: tie a resource's lifetime to an object's scope. When the object is destroyed, the resource is automatically…
- Rail fence cipherWrite the plaintext in a zigzag across a few rows, then read it off row by row — a transposition cipher that yields to a…
- RailwayModern PaaS with a visual project canvas — each service is a node, drag & drop dependencies between database + backend +…
- Rainbow BooksThe collective name for the CD standards, which Sony and Philips issued in binders of different colours.
- Rainbow tablePre-computed table of common passwords and their hashes — look up a hash instead of brute-forcing it.
- RakutenJapanese e-commerce + ecosystem — Hiroshi Mikitani founded 1997. Today a superapp: marketplace, bank, credit card, mobile…
- Ralf BurgerGerman programmer who demonstrated a virus at the CCC in 1986 and then printed virus source code in a book.
- Ralf-Philipp WeinmannGerman cryptographer and exploit writer who moved comfortably between paper proofs and working attacks on phones.
- RalinkTaiwanese Wi-Fi chipmaker found inside a remarkable share of the world's cheap USB adapters and home routers.
- Ralph LangnerGerman industrial-control-systems specialist who worked out what Stuxnet was actually for.
- Ralph MerkleInvented public-key cryptography as an undergraduate, had the idea rejected by the course, and ended up outside the history…
- RAM (Random Access Memory)The computer's short-term memory — fast, volatile, holding everything that's running right now.
- RAM diskA virtual "disk" that lives entirely in RAM, giving extreme read/write speed but vanishing on reboot (volatile). Useful for…
- RAMACThe world's first hard disk: fifty twenty-four-inch platters holding less than a single phone photo.
- RambusA memory company that makes almost nothing and lives on licences — best known for RDRAM and for suing half the industry.
- RampCorporate card and expense platform that, unusually, stakes its brand on getting customers to spend less.
- Ramp load/unloadA plastic ramp at the disk's edge onto which the heads are parked, lifting them clear of the platter instead of landing on…
- RANThe radio access network — everything between the phone and the core, meaning antennas, base stations and their control.
- Ran CanettiCo-author of HMAC and creator of the framework that decides whether a secure protocol stays secure once it meets other…
- RancherOpen source Kubernetes management platform. Multi-cluster UI: manage 100 clusters from one console. Rancher Labs (2014)…
- RAND CorporationThe US Air Force's Santa Monica think tank, where packet switching was dreamed up to survive a nuclear war.
- Random ForestAn ensemble of many decision trees — each trained on a random subset of data and features. Majority vote for the answer.
- Random number generatorA program or circuit that produces numbers meant to look random, which in cryptography must also be impossible for an…
- Random oracleAn idealised hash function that answers every new query with a random value, used as a model for proving security of…
- random_page_costThe planner's estimate of what it costs to fetch a page from a random location. The default of 4.0 describes a spinning hard…
- Randomness extractorA function that boils a lumpy, partly predictable entropy source down to fewer bits that are almost perfectly uniform.
- RandR (xrandr)The X11 extension that made it possible to change resolution, rotate and plug in monitors without restarting X.
- Range partitionPartitioning strategy: split data by range of partition-key values. Classic use: time-series where data is partitioned per…
- RangekeeperThe US Navy's mechanical fire-control computer, which from 1916 solved gunnery's founding problem: where the ship will be by…
- RansomwareMalicious code that encrypts your files and demands ransom (usually crypto) for the decryption key.
- Raphael GrayWelsh teenager, a.k.a. Curador, who stole tens of thousands of card numbers from online shops in 2000 and sent Viagra to…
- Raphael MudgeAmerican developer of Armitage and Cobalt Strike, the red team tool that became as popular with criminals as with the people…
- Rapid SelectorVannevar Bush's microfilm machine that looked documents up by content instead of by position — and is the actual blueprint…
- Rapid7The Boston company that bought Metasploit and with it custody of the most widely used tool in the industry's grey zone.
- RapidlokOne of the toughest copy protections on the C64 — custom GCR formatting on the disk plus a fast loader, built so an ordinary…
- RapidMinerVisual ML platform that began life as a university project called YALE and ended up part of Altair.
- RapidusJapan's state-backed attempt to leap straight to 2-nanometre chips after two decades off the leading edge.
- RapierA 2D and 3D physics engine written in Rust that also runs in the browser through WebAssembly.
- RARP (Reverse Address Resolution Protocol)ARP backwards: a machine that knows its own MAC address but not its IP address asks the network who it is. Standardized in…
- Rasmus LerdorfWrote a few CGI scripts to count visitors to his own CV — and accidentally produced the web's most used server language.
- Raspberry PiSmall ARM-based single-board computer — credit-card-sized, runs full Linux, $50-100.
- Raster barsThe smoothly gliding horizontal colour bands — the demoscene's signature, painted by swapping the background colour on every…
- Raster EffectGraphics effect that manipulates screen coordinates on a per-scanline basis while the display is actively being drawn…
- Raster image processorThe component that translates a page description language into the dot raster the printer's engine actually lays on paper.
- Raster interruptAn interrupt fired when the VIC-II reaches a chosen scanline, letting code change hardware registers partway down the screen.
- RasterisationWorking out which pixels a triangle covers — the foundation of all real-time graphics for thirty years.
- Rasterizer ordered views (ROV)A hardware guarantee that overlapping fragments read and write the same pixel in draw order, letting a shader do its own…
- RastertimeHow much of a frame a routine uses, measured in scanlines and made visible by changing the border colour while the code runs.
- Rate limitingCap how many requests a client may make per time window — "100 requests/min per IP".
- Rate limiting (ops)Limiting how many requests a client may make in a time period, to protect a service against overload, abuse, and unfair…
- RatioTwitter slang: when a tweet gets more replies than likes/retweets → signal the post is bad/dumb/provocative. "Ratio'd" =…
- Ratio (compressor)How hard a compressor squeezes whatever crosses the threshold — 4:1 means four decibels in becomes one decibel out.
- Ratio (getting "ratioed")When a post on Twitter/X gets more replies than likes — a sign that people disagree or are upset, since they stop to respond…
- RatioedWhen the replies to your post outnumber the likes, the audience has spoken, and it said no.
- Rational SoftwareThe company that put the three big methodology gurus under one roof and came out with UML, Rational Rose and an entire…
- ratpoisonA window manager with no mouse, no frames and no overlap, driven entirely by GNU Screen-style key bindings.
- RAVENNAAn open technology for uncompressed audio over IP networks, built for broadcasters rather than conference rooms.
- RAWUnprocessed sensor data from the camera — not an image yet, but the raw material an image can be developed from.
- RayUC Berkeley RISELab, 2017 — distributed compute for Python, primarily for ML. Commercialised as Anyscale.
- Ray TomlinsonThe BBN programmer who sent the first email between two computers in 1971 and chose the @ sign to separate the user from the…
- Ray tracingA rendering technique that follows light rays through the scene instead of projecting triangles onto the screen. Produces…
- Raycast vehicleA vehicle model whose wheels are not physical bodies but rays cast downward from the chassis to sense the ground and compute…
- RaycastingA rendering technique that shoots one ray per screen column into a 2D grid map to draw walls, faking 3D cheaply.
- raylibA stripped-down C library for games, built to teach — no editor, no dependencies, just a flat API.
- RaymarchingA 3D rendering technique where the camera "walks" through space in small steps until it hits a surface — compact enough to…
- RazerThe gaming mouse with three snakes in its logo that grew into an entire ecosystem of keyboards, laptops and acid-green RGB…
- Razor 1911One of the world's oldest cracking groups, founded in Norway in 1985 and still talked about long after most of its…
- RBAC (Role-Based Access Control)Permission model: users have roles (admin, editor, viewer), roles have permissions.
- RBBS-PCFree BBS software for the IBM PC, written in BASIC and handed out with source, which let thousands of hobbyists open a board…
- RBCD (Resource-Based Constrained Delegation)Delegation where the resource itself declares who may act on users' behalf against it. Requires no domain administrator to…
- RC2Ron Rivest's 1987 block cipher, tailored to slip past US export rules with short keys.
- RC4The stream cipher so small and fast it ended up everywhere — and so biased in its first bytes that it took WEP down with it.
- RC4 biasRC4's output is not uniformly random, and the non-randomness shows up in the very first bytes.
- RC5Ron Rivest's 1994 block cipher in which block size, key length and round count are all parameters.
- RC6RSA Security's AES candidate: RC5 stretched to a 128-bit block, with integer multiplication thrown in for good measure.
- RCA Mark IIA room-sized 1957 synthesizer built from vacuum tubes and programmed with punched paper, which became the heart of the…
- RCE (Remote Code Execution)The worst kind of vulnerability — the attacker can run arbitrary code on your server without being logged in.
- RCS (Rich Communication Services)The SMS successor — typing indicators, read receipts, high-quality media, group chat. Standardised by the GSMA, in practice…
- RDF (Resource Description Framework)The W3C's data model for the semantic web: everything is expressed as triples of subject, predicate and object.
- RE EngineCapcom's in-house engine, which took over from MT Framework and now carries more or less the publisher's entire catalogue.
- ReactThe frontend library from Meta — components, virtual DOM, declarative UI.
- ReAct (prompting pattern)Reasoning + Acting — an agent pattern where the LLM alternates between generating "Thought:" (reasoning) and "Action:" (tool…
- ReAct agentReasoning + Acting — an agent pattern (paper 2022) where an LLM alternates reasoning ("Thought"), action ("Action", e.g. a…
- React NativeMeta's cross-platform framework — build native iOS/Android apps with React + JavaScript. Launched 2015. Powers Facebook…
- React RouterDefault routing library for React — Michael Jackson + Ryan Florence (Remix team). v7 (2024) merged Remix into React Router.
- React SuspenseReact feature: declarative loading state. <Suspense fallback={<Spinner />}><DataComponent /></Suspense>. Child can "suspend"…
- Reaction emojiReplying to a message with a small emoji (👍❤️😂) instead of text. A lightweight response that confirms…
- Reactive signalsProgramming model for reactivity — observable values + auto-tracking of dependencies. Knockout (2010) → MobX → SolidJS made…
- Reactive StreamsA specification for asynchronous streams with non-blocking backpressure, developed 2013–2015 by people from Netflix…
- Read amplificationWhen a single logical read requires several physical read operations. In an LSM tree a key can exist on several levels, so a…
- Read channelThe circuitry that reconstructs bits from the analogue voltage the read head delivers — the hardest step between the…
- Read CommittedThe most common transaction isolation level (and PostgreSQL's default). A query only sees data that was committed when the…
- Read receiptNotification to the sender that the recipient has read the message. Three common levels: delivered (✓), read (✓✓)…
- Read repairWhen a read finds that different replicas have different values for the same key, the newest value is pushed back to the…
- Read replicaA read-only copy of a primary DB that follows along via WAL streaming. Scales read-heavy workloads horizontally — the…
- Read-after-writeThe verify technique where a read head sits just behind the write head and checks every block the instant it is written.
- Read-while-writeA read head sits just behind the write head so every block is read back and checked microseconds after it's written.
- Read/write headThe tiny electromagnetic transducer that flies nanometres above the platter, turning magnetic patterns into bits and back.
- Readiness probeA health check that determines whether a container is READY to receive traffic. If it fails, the pod is temporarily removed…
- readnewsUsenet's original reader: one article at a time, scrolling up the terminal, with a question after each.
- Real-timeSystems that must respond within a guaranteed time bound — not just "fast".
- Reality AdLib TrackerDOS tracker from the demogroup Reality for writing music straight for the FM chip on AdLib and Sound Blaster cards.
- Reality WinnerNSA contractor who leaked a report on Russian hacking of US election systems in 2017 and received the longest sentence to…
- RealNetworksThe company that made audio on the web possible in 1995, then spent a decade making people regret installing its player.
- RealtekTaiwanese chip designer whose cheap network and audio parts sit in a staggering share of the world's PCs.
- RealtimeKit (rtkit)A small Linux service that hands out real-time priority to ordinary user processes, so the sound server doesn't have to run…
- ReampingRecording the guitar dry and sending it back through a real amplifier at mix time, once you know what it should sound like.
- REAPERThe small, fast and almost impolitely cheap DAW from the man who wrote Winamp.
- Reason Studios (Propellerhead)The Stockholm company that built an entire studio rack in software — cables on the back included — and went by Propellerhead…
- Reasoning modelLLMs trained to "think" step by step before answering — better at maths, code, logic.
- Reasoning models ("thinking models")LLMs trained to produce long internal "thinking" traces before answering — better at maths, code, logic. Costs far more per…
- Rebecca BaceNSA research leader who funded and held together the early work on intrusion detection.
- Rebecca MercuriThe computer scientist who insisted that every election be recountable on paper, long before that was the conventional…
- Rebound attackA cryptanalytic technique that finds collisions in AES-like hash functions by searching the middle rounds first.
- rec.*Usenet's leisure hierarchy — music, games, films, books, cooking and everything else that wasn't work but happened during…
- rec.humor.funnyUsenet's moderated joke group, which for a while had more readers than almost anything else on the network.
- Recast NavigationAn open toolkit that builds a navmesh automatically from a level's geometry and runs pathfinding on it at runtime.
- Receipt printerThe small till printer that spools receipts off a paper roll — almost always thermal, cutting and feeding on its own.
- Reciprocal velocity obstacles (RVO)A method for letting many agents avoid each other smoothly by having each take half the responsibility for dodging.
- RecoilMeta's state-management library — popularised the "atom" + "selector" pattern. Archived January 2025 after the lead…
- Recommendation systemML system that suggests what you should watch, buy or read next.
- Reconstruction filterThe low-pass filter after a DAC that removes the images above the Nyquist frequency and turns samples back into a smooth…
- RECORD extension (X11)The X extension that lets one client eavesdrop on the protocol traffic between the server and every other client, intended…
- Recorded FutureSwedish-founded threat intelligence company that reads the internet at machine scale and sells the conclusions.
- Rectangle attackA boomerang-style attack that counts many differential pairs instead of a single path, which can make some key guesses…
- RecursionA function that calls itself to solve a problem.
- Recursive CTESQL feature: WITH RECURSIVE syntax for a recursive query. Use: traverse tree structures (org hierarchy, category trees)…
- Recursive queryA SQL query that calls itself to traverse hierarchies and graphs — implemented with WITH RECURSIVE. The standard way to…
- Recursive shadowcastingA field-of-view algorithm for grid games that scans each of eight octants tracking visible angle ranges, where blocking…
- ReCycle (REX)Propellerhead's program that chopped drum loops into slices at every transient and saved them as REX files, so a loop could…
- REDJapanese diplomatic cipher machine of the 1930s, broken by American cryptologists and replaced by PURPLE.
- REDRandom Early Detection — congestion avoidance algorithm. Sally Floyd + Van Jacobson, 1993. Drop packets probabilistically…
- Red HatProved you can build a billion-dollar company on software you give away — by selling support instead of licences.
- Red Pill (VM detection)Joanna Rutkowska's 2004 trick for telling whether code runs inside a virtual machine using a single CPU instruction.
- Red Sector Inc.German cracking and demo group that set the tone for the Amiga's megademos before folding into TRSI in 1990.
- Red teamSecurity team that acts as attackers to test defences — without warning the operations team.
- Red-black treeSelf-balancing binary search tree with "colour" invariants — Rudolf Bayer 1972, named by Leonidas Guibas (1978). The most…
- RedditLink aggregator and discussion platform — "the front page of the internet". Founded in 2005 by Steve Huffman and Alexis…
- REDengineCD Projekt RED's in-house engine, built for the big open worlds of The Witcher 2 and 3 and Cyberpunk 2077.
- RedisIn-memory key-value database — blazing-fast cache, session store, pub-sub, queues.
- Redis ClusterRedis native sharding mode. 16,384 hash slots distributed across master nodes; each master has 0-N replicas. Client knows…
- Redis SentinelRedis HA solution without sharding. Sentinel processes (3+) monitor master + replicas, vote quorum on failover. Client asks…
- Redis StreamsAppend-only stream data structure in Redis — like a lightweight Kafka. Consumer groups, XADD/XREAD/XACK commands. Added in…
- Redo logMySQL/InnoDB's equivalent of the write-ahead log: it stores committed changes so they can be "redone" after a crash. It…
- RedpandaKafka API-compatible message queue written in C++ (Seastar framework). Single binary, no JVM, no ZooKeeper/KRaft setup.
- Reduced write currentA control signal that lowered the write current on the inner tracks, where the bits crowd together and too much current…
- Reduced-round attackAn attack on a cut-down version of a cipher, with fewer rounds than the real thing, measuring how much margin is left.
- ReduxPredictable state container for JS — Dan Abramov & Andrew Clark (2015). Implements the Flux architecture as a single store +…
- Redux Toolkit (RTK)Official modernisation of Redux — eliminates boilerplate through createSlice + Immer. Default recommendation for all Redux…
- redux-sagaRedux middleware for handling side effects (async API calls, navigation) via ES6 generators. Yassine Elouafi, 2015. Powerful…
- RefactoringChange the structure of code without changing its behaviour — making it easier to read, modify, test.
- ReferenceIndirect access to a value — instead of the value itself you have a pointer/handle. Allows multiple variables to share the…
- Referential integrityThe guarantee that foreign keys always point to a row that exists — no "orphans".
- Referential transparencyA property where an expression can be replaced with its value without changing the program's behavior. add(2,3) can always…
- ReflectionA program's ability to inspect and manipulate its own structure at runtime — list classes, get fields, invoke methods by…
- Reflection attackAn attack that exploits round keys recurring in reverse order, so that one part of the cipher undoes another.
- Reflection loopLLM evaluates its own output, identifies errors, generates a new attempt — repeats until satisfied. "Reflexion" paper Noah…
- Reflection probeA point in the scene that captures its surroundings as a cubemap, letting glossy surfaces reflect the room without…
- Reflection XWRQ's X server for Windows PCs, the perennial runner-up to Exceed in companies that wanted to reach their Unix boxes from…
- Reflective shadow maps (RSM)A shadow map reused as a light source: every lit texel becomes a tiny secondary lamp that casts indirect light.
- ReflectorThe fixed disc in the Enigma that sent the signal back through the rotors and made encryption self-reciprocal.
- ReflexionAgent pattern where the LLM verbally reflects on failed attempts, stores the reflection in memory, and tries again — "verbal…
- Refresh rateHow many times per second the display redraws its image, measured in hertz. 60 Hz is the floor, 120–144 Hz is common today…
- Refresh tokenA long-lived token (days/weeks/months) exchanged for a new access token when the old one expires — without asking the user…
- Regenerative memoryMemory that forgets if left alone: its contents must be read and rewritten in a constant cycle just to persist.
- Regex (Regular Expression)A compact language for finding and matching patterns in text.
- Region (X11)Xlib's data type for an arbitrary area expressed as a set of non-overlapping rectangles — the thing you clip against…
- Register fileThe collection of the processor's registers — the fastest storage of all, where the data the CPU is working with right now…
- Register renamingThe technique of mapping the few architectural registers the instruction set exposes (e.g. 16 in x86-64) to a much larger…
- RegistryServer hosting container images — Docker Hub, GitHub Container Registry, AWS ECR.
- Regression testA test that ensures something which once worked still does. A regression is therefore not just any bug — it's a defect in…
- RegularizationThe collective name for everything done to stop a model memorizing the training data instead of learning the pattern. The…
- Reinforcement learning (RL)ML paradigm where an agent learns through reward — try, get feedback, improve.
- Related-key attackAn attack model in which the attacker can observe encryption under keys that are known to be related to each other.
- Related-key boomerang attackA boomerang attack in which the two half-differentials are also allowed to run under different but related keys.
- Relational database (RDBMS)DB model based on tables (relations) with rows + columns. Query language: SQL. Edgar F. Codd, IBM, 1970. Dominated the DB…
- Relative color syntaxThe CSS syntax that lets one colour be defined in terms of another: take this one, take it apart into channels, change one…
- RelayFacebook's GraphQL client for React. 2015. Pragmatic + opinionated: fragment colocation, cursor-based pagination (Relay…
- Relay (BITNET)The chat program on BITNET's mainframes that had channels and nicknames three years before IRC existed.
- Relay computerThe computer built from the telephone network's basic part: thousands of electromechanical switches clacking their way to an…
- Relay InterpolatorThe first machine that could tell when it had got the answer wrong — and therefore the first one anybody dared leave running…
- RelayNetRelayNet International Message Exchange (RIME), a large BBS network from the PCBoard world around 1990.
- RelcomThe first Soviet computer network connected to the internet, built by a Moscow programmers' cooperative in 1990.
- Release groupThe named crews that crack, package and release — the scene that competes to be first rather than to make money.
- Relief mappingA per-pixel shader technique that fakes real surface depth by ray-marching a height map, so bricks and cobbles occlude one…
- RemanenceThe magnetisation left behind once the applied field returns to zero — where a bit is actually stored.
- Remedy EntertainmentA Finnish studio with demoscene roots that turned bullet time into a game mechanic with Max Payne.
- RemixReact framework with web-fundamentals focus (forms, progressive enhancement, nested routing). Michael Jackson + Ryan…
- RemoteAccessAustralian DOS BBS software that started as a QuickBBS-compatible alternative and became one of the most common packages in…
- Ren'PyA game engine for visual novels in which the script itself is the program.
- Renaud DeraisonThe Frenchman who wrote the Nessus vulnerability scanner as a teenager and later closed its source.
- Render"Heroku 2.0" — git-based deploy, managed Postgres/Redis, static sites, cron jobs. One of the big winners after Heroku killed…
- Render graphA data structure that describes a frame's render passes and their resource dependencies as a graph, letting the engine…
- Render passA bounded rendering phase in modern graphics APIs that declares up front which buffers it reads and writes, so the driver…
- Render queueRather than drawing in scene order, the engine collects draw calls and sorts them by a packed sort key.
- Render targetAn off-screen buffer the GPU draws into instead of the screen, so the result can be read back as a texture.
- Render threadA dedicated thread that feeds the GPU the previous frame's draw calls while the game thread is already simulating the next…
- Render to textureRendering a scene or sub-pass into an off-screen texture so the result can be fed back as input to a later pass.
- Render-blockingResources (primarily CSS and synchronous scripts) that must be loaded and processed before the browser can paint anything on…
- RenderDocA free graphics debugger that captures a single frame and lets you take it apart call by call.
- Rendering equationThe integral that all photorealistic rendering tries to solve: the light leaving a point equals what it emits plus all…
- RenderWareBritish middleware that powered half the PlayStation 2's catalogue — until EA bought it and quietly retired the licence.
- RenditionThe graphics startup whose Vérité cards earned their own Quake port — and were then bought for the engineers.
- Renegade (BBS)DOS-based BBS software built on Telegard's code, a household name in the North American warez and underground scene of the…
- RenesasJapan's microcontroller industry rolled into one company — and with it, a large share of the electronics in any given car.
- RenoiseCommercial 2000s tracker that took the tracker's vertical pattern editing and married it to VST and a modern audio engine.
- RenovateA more configurable alternative to Dependabot — Rhys Arkins (now Mend, formerly WhiteSource), 2017. Runs as a GitHub App…
- Reorder buffer (ROB)The structure that lets an out-of-order CPU execute instructions in any order yet "retire" (make the results visible) in…
- ReparentingThe window manager trick of moving an application's window inside a frame of its own, so a title bar and buttons can be…
- ReparentNotifyThe X11 event announcing that a window has a new parent — usually because the window manager just wrapped a frame around it.
- Repeatable ReadIsolation level where the same row read twice in one transaction is guaranteed to return the same value. Prevents…
- ReperforatorA receiving teleprinter that punches the incoming signal onto paper tape instead of printing it on a page.
- Repetition penaltySampling parameter that dampens the probability of tokens that have already appeared in context — counteracts LLM loops…
- REPL (Read-Eval-Print Loop)An interactive shell where you write code one line at a time and see the result immediately.
- Replay attackRecord valid communication and replay it later — without understanding the contents.
- Replay systemPlays a match back afterwards by storing the players' inputs and re-running the simulation, not by filming the screen.
- ReplayGainA way of evening out perceived loudness between tracks by storing a volume adjustment in the file's tags instead of altering…
- ReplicateA cloud service that runs machine-learning models behind an API — pay by the second, no GPU to own.
- ReplicationCopy data to multiple database instances — for redundancy, read load balancing, geographic proximity.
- Replication slotPostgreSQL mechanism: server reserves WAL segments until a specific consumer (replica or logical decoding client) has…
- ReplitA browser-based development environment where you write, run and deploy code straight in the browser without installing…
- Reply guySocial media phenomenon: users (statistically often men) who reply unprompted to popular posts from strangers (statistically…
- Reply threadTree structure of reply-to-reply in a conversation. Twitter: linear (all replies shown below), Reddit: nested (replies have…
- Report flowThe process of reporting content or accounts that break the rules to the platform — pick a reason, submit, and the post…
- Reporting APIThe browser's mechanism for sending home reports about things going wrong out in the field that your own error monitoring…
- Repository (Repo)A folder that tracks the entire history of a project — every change, by whom, when, why.
- Repository patternAbstraction between domain logic and storage — domain code talks to a UserRepository interface, not directly to…
- RepRapAdrian Bowyer's 2005 project: an open-design 3D printer that prints its own parts.
- Reproducing punchThe punched-card machine whose whole job was copying a deck — which in this era was a scheduled machine run, not a command.
- requestAnimationFrameA web API for scheduling a function to run just before the browser's next repaint, synchronized with the screen's refresh…
- requestIdleCallbackA web API for scheduling low-priority work so it runs when the browser is idle anyway (in the gaps between frames), without…
- ReRAM (Resistive RAM, RRAM, "memristor")Non-volatile memory where bits are stored as resistance states in a metal-oxide film. Crossbar architecture enables analog…
- RerankerStep 2 of a RAG pipeline — after the vector DB fetches ~50 candidates, a cross-encoder re-orders them by more detailed…
- Research Machines (RM)The Oxford firm that filled British classrooms with computers — the duller rival to the BBC Micro, for anyone at school in…
- reSIDDag Lem's software model of the C64's SID chip — accurate enough to mimic even the grubby analogue stages that made the…
- Residual connection (Skip connection)A shortcut that adds a layer's input to its output: y = F(x) + x. Introduced in ResNet (He et al., 2015) and since then…
- Resizable BARA PCIe feature that lets the system change the size of the "Base Address Register" window so the CPU can access all of the…
- Resize ObserverA web API that notifies when a specific element's size changes — not just the whole window. It solves the problem of…
- ResizeRequestThe X11 event that lets one client intercept other clients' attempts to resize a window instead of the server carrying them…
- ResolutionNumber of pixels wide × tall on a display — 1080p (1920×1080), 1440p, 4K (3840×2160), 8K.
- Resource barrierThe instruction in modern graphics APIs that announces when a resource changes use — without it, the GPU reads half-written…
- Resource ID (XID)The 29-bit number identifying every window, pixmap, font and cursor in an X server — chosen by the client itself, so that a…
- Resource requests/limitsHow you specify a container's CPU and memory needs in Kubernetes. Request = what the pod is guaranteed (used for…
- ResourceQuotaKubernetes object that limits total resource use per namespace: max CPU/memory aggregated, number of pods, number of…
- Respawn EntertainmentFounded by the Call of Duty creators after a bitter split with Activision — and home to Apex Legends.
- Responsive designWebsite that adapts its layout to screen size — one codebase, works on mobile and desktop.
- Responsive imageServe different image versions based on screen size and pixel density.
- REST (Representational State Transfer)A design style for APIs that uses HTTP consistently and predictably.
- resticA backup tool written in Go by Alexander Neumann. One static binary, an encrypted and deduplicated repository, and no…
- ReSTIRA technique that reuses and combines light samples across neighbouring pixels and frames to make ray-traced lighting…
- RestitutionThe coefficient of restitution e: how much of its speed an impact keeps — the measure of how bouncy something is.
- ResumabilityQwik framework concept: server serializes entire app state to HTML, client resumes execution from where server left without…
- Retained modeA UI or graphics approach where the application builds a lasting model of the scene that the library keeps, and you mutate…
- Retention (Usenet)How long a news server keeps articles before purging them — a couple of weeks in the 1980s, more than a decade for today's…
- Reticle limitThe maximum physical size a single chip (die) can have, set by the lithography machine's exposure field — around 858 mm² for…
- RetinaApple's marketing name for displays with pixel density high enough that individual pixels can't be perceived at normal…
- RetirementThe final step in an instruction's life in the CPU, where its result is made permanent and visible in the architectural…
- RetNet (Retentive Network)Architecture from Microsoft Research in 2023 that swaps attention for retention, a mechanism computable in three different…
- RetoolA low-code kit for the ugly internal admin panels every company needs but no developer wants to hand-write.
- RetryTry-again strategy on transient errors (network timeout, 503). Default in modern SDKs. Must be paired with exponential…
- Return stack buffer (RSB)A small hardware stack in the CPU that specifically predicts the return address from function calls. When a function is…
- RETURNING clausePostgreSQL extension: INSERT/UPDATE/DELETE returns the modified rows. INSERT INTO users (name) VALUES ('Alice') RETURNING…
- REU (RAM Expansion Unit)Commodore's external RAM module for the C64 and C128, with a DMA chip that shifts whole blocks between main and expansion…
- Reverb zoneA volume in the scene that stamps the surrounding space's reverberation — a cave's echo, a bathroom's ring — onto every…
- Reverberation time (RT60)How long it takes sound in a room to decay by 60 dB after the source stops – the single most quoted number in acoustics.
- Reverse engineeringThe practice of dissecting software to understand how it works — often to remove restrictions, break copy protection, or…
- Reverse Polish notation (RPN)A way of writing expressions where the operator comes after its operands — 3 4 + instead of 3 + 4 — so parentheses become…
- Reverse proxyServer that accepts incoming traffic and forwards it to a backend.
- Reverse reverbReverb that swells up before a sound instead of decaying after it.
- Reverse-ZThe trick of storing depth reversed — the near plane as 1, the far plane as 0 — so a floating-point buffer's precision…
- Revision (demoparty)The largest pure demoparty of the present day — the German Easter party that inherited Breakpoint's role as the scene's…
- RevolutBritish neobank that began as a currency card at the interbank rate and swelled into accounts, stock trading and crypto in…
- Reward hackingWhen a model finds a way to score highly without doing the thing the score was meant to measure. Goodhart's law in…
- ReWireA protocol that let two music programs run as one: one drove transport and tempo, the other piped its audio straight into…
- RF64The EBU's extension of WAV with 64-bit size fields, so a recording no longer stops dead at 4 GB.
- RFC (Request for Comments)Technical specification documents from the IETF — the definition of the internet protocols.
- RFC 1036The 1987 specification describing what a Usenet article looks like and how servers pass it between them.
- RFC 19181996 specification that reserves three IPv4 blocks for private use: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16. Never routes…
- RFC 822The 1982 standard that decided what an email looks like: header lines, a blank line, then the text — and still holds in…
- RFC 850The first document to write down what a Usenet article should look like — four years before anyone needed to change it.
- RFC EditorThe function that numbers RFCs, copy-edits them and makes sure they never change once published.
- RGB (Red, green, blue)An additive colour model: red, green and blue light add up to produce every other colour. All off is black, all full is…
- rgb.txtX11's list of colour names, AliceBlue, PapayaWhip, DarkSlateGray and the rest, which by way of Netscape and SVG became the…
- RHEL (Red Hat Enterprise Linux)Red Hat's paid enterprise Linux. 10-year support per major version. The de-facto standard in larger companies, banks…
- RIAA equalizationThe frequency curve every vinyl record is cut with and every phono preamp has to undo — bass down, treble up, and then the…
- Ribbon microphoneA microphone in which a corrugated aluminium ribbon a few micrometres thick hangs in a magnetic field and is itself the…
- Rich SkrentaWrote Elk Cloner at fifteen, one of the first computer viruses to spread in the wild — and went on to build search companies.
- Richard BartleBritish game designer and academic who co-wrote the first MUD at the University of Essex, then spent a career explaining why…
- Richard BejtlichFormer Air Force officer who turned network security monitoring into a discipline, starting from the premise that intrusions…
- Richard ClarkeThe American official who warned about al-Qaeda before 9/11 and about cyberwar long before the word was common currency.
- Richard ClaytonCambridge researcher who came to academia from an ISP and studies online crime with an operations engineer's scepticism.
- Richard KemmererThe UCSB professor who gave the world a systematic way to hunt covert channels, rather than hoping someone stumbled on them.
- Richard PryceLondon teenager who, as Datastream Cowboy, got into the US Air Force's research network in 1994 with a modem and a home…
- Richard StallmanStarted the free software movement in 1983 and designed the legal mechanism — copyleft — that made it self-reinforcing.
- Rick AdamsThe sysadmin who ran one of Usenet's most important hubs on the side, then built one of the world's first commercial…
- RickrollTricking someone into clicking a link that promises one thing and delivers the music video for Rick Astley's 1987 single…
- RicohJapanese imaging giant whose semiconductor arm happened to build the brains of an entire console generation.
- Ricoh 2A03The custom chip inside the NES — a 6502 CPU and a five-channel sound unit on one die, which made it chiptune's second…
- Rigetti ComputingThe upstart that set out to build superconducting quantum computers in its own fab rather than wait for IBM and Google.
- RiggingBuilding a skeleton of bones with controls and constraints so an animator can pose and deform a 3D model without touching…
- Rigid bodyAn idealised body that never deforms, whose entire state fits in a position, an orientation and its two velocities.
- RijndaelRijndael is the block cipher that became AES, designed by the Belgians Joan Daemen and Vincent Rijmen.
- Rim lightingA bright edge tracing an object's silhouette that lifts it off the background — borrowed from the backlight of photography…
- Ring AttentionA method for training and running models with context windows of millions of tokens by splitting the sequence across…
- Ring busIntel's interconnect topology where CPU cores, cache segments, and I/O sit on a ring-shaped data bus. Data travels around…
- Ring counterTen flip-flops in a loop with exactly one lit — how ENIAC counted in decimal without ever detouring through binary.
- Ring modulationMultiplying two signals into new, inharmonic frequencies — on the SID, a cheap version that yields bells, gongs and metallic…
- RingCentralAn American company that replaced the office phone switch and desk handsets with a cloud service for calls, video and…
- RingstellungEnigma's extra setting: the alphabet ring could be turned relative to the rotor wiring.
- rioPlan 9's window system since the third edition in 2000: a file server in which every window is a directory holding a…
- Riot GamesThe studio that built an entire company on one free game, League of Legends, and later an anti-cheat that lives in the…
- RIP (Routing Information Protocol)The first widely used routing protocol on the internet. Distance vector with hop count as its only metric, and a maximum…
- RIPEMD-160A European 160-bit hash function from 1996, best known today as half of how Bitcoin addresses are derived.
- ripgrep (rg)Recursive search across file trees, written in Rust by Andrew Gallant in 2016. Faster than grep, ack and The Silver…
- RIPscripA graphics protocol that gave dial-up bulletin boards real vector images, clickable buttons, and a mouse — ANSI art's…
- RISC OSAcorn's operating system for the Archimedes, whose desktop in 1989 had an icon bar, anti-aliased fonts and drag-and-drop…
- RISC vs CISCThe classic design-philosophy clash: RISC (Reduced Instruction Set Computer) with few, simple, uniform instructions, versus…
- RISC-VOpen ISA — anyone can design CPUs around it, without paying licensing fees to ARM or Intel.
- RisingWaveOpen-source alternative to Materialize — streaming SQL, compatible with the Postgres protocol, built in Rust…
- RISKS DigestThe moderated newsletter that has been collecting cases of computers hurting people since 1985.
- RiverbedThe appliances that made the head-office file server feel local to the branch three time zones away.
- RivosStealth startup building RISC-V server chips for AI — and the one Apple sued for poaching engineers who brought secrets with…
- RK4 (Runge–Kutta)A fourth-order integrator that samples acceleration four times per step and blends them — far more accurate than Euler for…
- RKERancher Kubernetes Engine: a distribution that runs the entire control plane in Docker containers, so a cluster needs…
- RKE2Rancher Kubernetes Engine 2 — a security-hardened Kubernetes distribution built for government and regulated industries.
- RL (Reinforcement Learning)ML paradigm where an agent learns by trial-and-error in an environment, rewarded/penalized by a reward signal. No labeled…
- RLAIFReinforcement Learning from AI Feedback — replaces human raters in RLHF with an AI rater. Anthropic + Google papers 2023.
- RLHF (Reinforcement Learning from Human Feedback)The technique that turns a raw LLM into something helpful, harmless and polite: humans rank AI answers and the model learns…
- RLL (run length limited)A family of encodings that caps how many zeros may sit between two flux transitions, letting bits pack tighter without…
- RLL encodingSqueezed another half again out of 1980s hard disks by controlling how many zeros could sit between flux transitions.
- rloginBSD's remote login from the early 1980s, which trusted the machine you came from instead of asking you for a password.
- RM4SCCRoyal Mail's four-state barcode, where every bar carries a top tick, a bottom tick, both or neither — a picket fence…
- RMEA German maker of audio interfaces better known for its drivers than its hardware — which, in that business, is the highest…
- RMS levelThe root mean square of a signal over a time window – a measure of how much energy the sound carries, as opposed to how high…
- RMSNormSimplification of LayerNorm — normalise by the root mean square only, skip the mean subtraction. Slightly faster, equal or…
- rn (newsreader)Larry Wall's 1984 Usenet reader, which gave the world the kill file before he gave it Perl.
- RNG (Random Number Generator)Generates (pseudo-)random numbers. Two classes: PRNG (deterministic from seed, for games/simulation) and CSPRNG…
- RNN (Recurrent Neural Network)Neural network for sequences — has a "hidden state" that propagates across time steps, letting information from earlier…
- RNNoiseReal-time speech noise suppression in which a small neural network only decides the gain — everything else is classic signal…
- ROAMBuilds terrain as a binary triangle tree and splits or merges triangles every frame against a screen-error metric…
- RoamingUsing a network other than your own and still being billed by your home operator.
- Rob HubbardThe Briton who squeezed a full synth out of the C64's three sound channels, and set the template for 8-bit game music doing…
- Rob JoyceThe NSA's hacker-in-chief, who took the stage in 2016 to tell defenders what makes his job hard.
- Rob NorthenBritish programmer whose Copylock protection sat in countless Amiga and Atari ST games and became the crackers' favourite…
- Robert CourtneyThe IBM veteran behind the first quantitative risk analyses and a handful of laws that still hold.
- Robert GrahamAmerican security researcher who wrote BlackICE, demonstrated sidejacking and built masscan to sweep all of IPv4 in minutes.
- Robert HansenThe web security researcher RSnake, whose XSS cheat sheet taught a generation how filters fail.
- Robert M. LeeFounder of Dragos and the person who turned industrial control system security into a discipline with its own threat actors.
- Robert McElieceThe information theorist whose 1978 cryptosystem was ignored for forty years because the keys were too big — and then turned…
- Robert MoogAmerican engineer (1934–2005) whose voltage-controlled modules turned the synthesizer into something you could buy, play and…
- Robert Morris (cryptographer)The Bell Labs mathematician who designed Unix password protection, then became chief scientist at the NSA – and whose son…
- Robert N. M. WatsonThe FreeBSD developer whose sandboxing ideas ended up inside Apple's operating systems, and whose hardware research aims to…
- Robert NoyceKnown as the Mayor of Silicon Valley — invented the silicon integrated circuit and founded two of the industry's most…
- Robert SchifreenBritish journalist who broke into Prestel in 1984 and read Prince Philip's mailbox — and whose acquittal gave the UK its…
- Robert Tappan MorrisThe grad student whose 1988 experiment brought the internet to its knees, and who went on to become an MIT professor and…
- Robert WinternitzThe Stanford mathematician behind the Winternitz signature, the hash-chain trick now holding up standardised post-quantum…
- Robin SeggelmannThe PhD student who wrote OpenSSL's heartbeat extension — and with it, by plain oversight, Heartbleed.
- RobloxUser-generated games platform — 80M+ daily users, mostly kids aged 8–16. Creators build games in Lua (Roblox Studio), earn…
- ROBOT attackROBOT is Bleichenbacher's 1998 padding oracle, revived in 2017 against TLS servers that still performed RSA key exchange.
- robots.txtA text file at a site's root telling web crawlers (Googlebot, Bingbot) what they can and can't index.
- ROC-AUCA measure of how well a model ranks, independent of the threshold you pick. The ROC curve plots the true positive rate…
- RoCERDMA over Converged Ethernet — InfiniBand-like RDMA on Ethernet hardware. RoCEv1 is L2-only, RoCEv2 (2014) is L3-routable…
- Rock RidgeAn ISO 9660 extension that smuggled Unix semantics — long names, permissions, symlinks — onto a CD.
- RockchipA Chinese ARM chip designer that went from MP3 players to Chromebooks and serious single-board computers.
- RocketMailOne of the very first webmail services, in 1997; Yahoo bought it and turned it into Yahoo Mail.
- RocksDBAn embedded key-value store from Meta, forked from Google's LevelDB in 2012 and optimized for SSDs and multi-threaded…
- Rockstar GamesThe New York publisher behind Grand Theft Auto, which ships few games, rarely, and sells them by the hundred million.
- Rockwell AutomationThe largest pure-play automation vendor in the US, home of Allen-Bradley PLCs and the Logix platform.
- ROCmAMD's open source GPU compute stack. Competitor to Nvidia's CUDA. Launched 2016. Powers AMD Instinct MI300X accelerators…
- Roger DingledineMIT-trained computer scientist who built Tor together with Nick Mathewson and Paul Syverson.
- Roger NeedhamBritish computer scientist (1935–2003) who laid the groundwork for how computers authenticate each other over an untrusted…
- Roger SchellUS Air Force officer who pushed the Orange Book into existence and made formally verifiable security kernels government…
- ROHMJapanese semiconductor maker that started with resistors and now leads in silicon carbide.
- Roland D-50Roland's first fully digital synth (1987), which stitched short samples onto subtractive synthesis and called the result LA…
- Roland GSRoland's 1991 extension of General MIDI, adding extra sound banks, more drum kits and controllable effects.
- Roland Juno-106Roland's six-voice analogue synth from 1984, with digitally controlled oscillators, MIDI and a chorus that turned out to be…
- Roland MT-32Roland's 1987 sound module that set the standard for high-end DOS game music before General MIDI took over.
- Roland RE-201 Space EchoRoland's 1974 tape echo, with an endless tape loop, three playback heads and a spring reverb in the same box.
- Roland TB-303A bass machine meant to replace the bass player for solo guitarists, which failed at that completely and invented acid house…
- Roland TR-808The drum machine that was meant to sound like drums, failed, and ended up as the sound of hip-hop, electro and trap instead.
- Roland TR-909Roland's 1983 drum machine that flopped in the shops and went on to become the very pulse of house and techno.
- Rolf RollesA reverse engineer who specialises in breaking the kind of obfuscation that turns a program into bytecode for a secret…
- RollbackReturning to a previous version after a failed deploy.
- Rollback netcodeCarry on from a guess about the opponent's input, then rewind and recompute when the real one turns up.
- Rolling deployUpdate servers a few at a time instead of all at once — no downtime if one is taken out of traffic at a time.
- Rolling updateThe default strategy for updating a Kubernetes deployment: replace the old pods gradually, a few at a time, with new ones…
- RollupJavaScript bundler. Rich Harris (Svelte creator), 2015. Pioneered tree-shaking — strip unused exports from ESM imports…
- ROLLUP (SQL)A SQL shortcut within GROUPING SETS that generates hierarchical subtotals. GROUP BY ROLLUP (year, month, day) gives totals…
- ROM (Read-Only Memory)Memory that retains data without power — where firmware and boot code live.
- ROM (MUD)Rivers of MUD — an extension of Merc that became the codebase more MUDs started from than any other.
- Roman SeleznevRussian card fraudster known as "Track2" who received one of the longest sentences ever handed down for computer crime in…
- RomplerAn instrument that plays factory samples out of ROM but can't record its own — a sampler with the record button surgically…
- Ron DeibertThe political scientist who built a university lab to track state hackers — much to the annoyance of the spyware vendors it…
- Ron GulaFormer NSA penetration tester who built the Dragon intrusion detector and then turned Nessus into a company.
- Ron RivestThe R in RSA and the R in CLRS — also the author of MD5, which he now advises against using.
- Ronald CramerDutch cryptographer who, with Victor Shoup, proved that practical encryption can resist chosen-ciphertext attacks without…
- Rook (Ceph on Kubernetes)Operator that runs the Ceph storage system inside Kubernetes, giving the cluster block, file and object storage without any…
- Room 40The British Admiralty's codebreaking section in the First World War, named after the room it worked in.
- Room correctionMeasure how the room distorts the speakers at the listening position, then compute a filter that undoes the damage.
- Room modesStanding waves between a room's walls that make some bass notes boom and others vanish.
- Rooms (Xerox PARC)The 1986 research system in which Austin Henderson and Stuart Card gave each task its own "room" with its own windows: the…
- Rooms and corridorsThe classic dungeon-generation recipe: scatter non-overlapping rectangular rooms, then connect them with corridors.
- RootThe Unix superuser — the account with UID 0, for which permission checks are simply skipped.
- Root guardA Spanning Tree feature that prevents a switch in the "wrong" place in the network from becoming the root bridge. If a port…
- Root menuThe menu that pops up when you click the empty desktop background, and which in many window managers is the entire…
- Root motionDriving a character's actual movement from the animation's root bone rather than from code, so the feet land where the…
- Root signatureDirect3D 12's contract declaring exactly which resources a shader expects and how they are bound to the pipeline.
- Root windowThe window that covers the entire screen in X11, and the ancestor of every other window on it.
- RootkitMalware that hides itself in the OS kernel — extremely hard to detect and remove.
- Rootless containerA container that runs without root privileges — neither the container runtime nor the process inside needs to be root on the…
- ROP (Return-Oriented Programming)Exploit technique that bypasses DEP/NX — use "gadgets" (existing code snippets in the program) instead of injecting code.
- Rop GonggrijpDutch hacker who helped start an ISP and talked his country out of voting by computer.
- RoPE (Rotary Position Embedding)How most modern LLMs encode token position — rotation in vector space instead of an additive embedding.
- RoPE scalingTechniques for extending the context length of models that use RoPE (Rotary Position Embedding) by rescaling the position…
- Rosario GennaroCryptographer whose work on threshold signatures and quadratic arithmetic programs sits underneath both crypto wallets and…
- Ross AndersonThe Cambridge professor who argued that security fails far more often through incentives, sloppiness and bad procedure than…
- Ross UlbrichtFounder of Silk Road, the first big darknet market, who was undone by an old forum post.
- ROT13A Caesar cipher with a shift of 13 — its own inverse, and never intended as security.
- ROT47A ROT variant that rotates the 94 printable ASCII characters by 47 places, making it its own inverse.
- RotatePropertiesAn entire X protocol request whose job is to shuffle eight cut buffers along by one — and very little else.
- Rotational cryptanalysisAn attack on ciphers built from addition, rotation and XOR, where simplicity turns out to be the weakness.
- Rotational latencyThe wait for the target sector to spin under the head after it reaches the right track — half a revolution on average, gone…
- Rotor machineThe cipher machine that changes alphabet on every keystroke by routing current through wheels that turn out from under it.
- Rotor orderThe Walzenlage was which rotors an Enigma used and in what order, part of the daily key.
- RotozoomerThe effect that rotates and zooms a texture in real time — the early-90s way to show you had fixed-point maths down.
- Round functionThe function repeated in every round of a block cipher, mixing the data with key material.
- Round keyThe subkey used in a single round of a block cipher, derived from the main key by the key schedule.
- Round robin (sampling)Recording the same note several times and letting the sampler cycle through the takes, so repeated hits don't sound…
- Round trip (X11)A request that must wait for the server's reply before the program can continue: the most expensive operation in the X…
- Round-trip latencyThe time from a note entering the audio interface to it coming back out of the headphones, after a lap through the computer.
- Route cipherThe letters are read out of a grid along a fixed path, such as a spiral, a zigzag, or some other route.
- Route flappingA route announced and withdrawn over and over — whose trembling propagates through the entire internet routing table.
- Route poisoningA loop-prevention technique in distance-vector routing (RIP, EIGRP) where a router that has lost a route actively advertises…
- Route redistributionTaking routes learned via one routing protocol and injecting them into another — e.g. bringing OSPF routes into BGP, or…
- Route summarizationMerging several specific network prefixes into one larger one ("supernet") in routing advertisements. It shrinks routing…
- Route targetThe label deciding which VPN routes land in which customer's routing table. It is this, not the route distinguisher, that…
- Route-mapA flexible "if-this-do-this" tool in routing: a sequence of rules that match traffic or routes on various criteria and then…
- RouterDevice that forwards packets between different networks — the foundation of the entire internet.
- Router Advertisement (RA, IPv6)IPv6 packet the router sends (multicast, every ~7-200 seconds) announcing its presence + prefix + flags (DHCPv6 needed?).
- Router Advertisement flagsRA packets' flags control how clients should address themselves: M (Managed config, run DHCPv6), O (Other config, run DHCPv6…
- RouterOSMikroTik's Linux-based router operating system. It runs on all their hardware and can also run on plain x86 or in a virtual…
- Routing tableA router's lookup table — for each destination prefix, which interface/next-hop the packet should be sent to. Uses longest…
- RövarspråketA Swedish children's word game where every consonant is doubled with an o in between.
- RovioFinnish studio that made fifty-odd forgettable games and then Angry Birds, one of the first big hits of the smartphone era.
- Row lockLock on individual rows instead of entire table. Standard for UPDATE/DELETE in modern DBs. Enables high concurrency: 100…
- Row storageClassic DB layout: rows stored contiguously — all columns for row 1, then all columns for row 2. Optimal for OLTP where…
- Row-level security (RLS)Per-row authorisation built into PostgreSQL since 9.5. The database filters out rows the user isn't allowed to see, whatever…
- RowhammerBy reading the same DRAM row fast enough, an attacker can flip bits in the neighbouring row — bypassing every software…
- ROX DesktopThe desktop environment that set out in 1999 to keep the RISC OS way of working — everything is a file, everything is…
- Roy TrubshawThe Essex student who wrote the first MUD in 1978, then handed it to Richard Bartle when graduation got in the way.
- rp_filter (Reverse Path Filtering)Linux setting that drops incoming packets whose source address the kernel would not route back out the same interface. An…
- RPG MakerA Japanese tool series for building 16-bit-style role-playing games without writing code — or with code, once you want to.
- RPKI (Resource Public Key Infrastructure)Resource Public Key Infrastructure — a system for cryptographically verifying that an autonomous system actually has the…
- RS-485A robust serial standard for differential signaling over long distances (up to ~1200 m) and in electrically noisy…
- RSAThe first practical public-key system — secure exactly as long as nobody can factor the product of two large primes.
- RSA blindingA countermeasure against timing attacks in which RSA decryption runs on a randomly multiplied value that is then removed.
- RSA SecurityThe company founded to monetise the RSA patent, later better known for SecurID tokens and an NSA scandal.
- RsbuildA high-level build tool on top of Rspack (Rust-based webpack reimplementation) from ByteDance.
- RSC (React Server Components)React components that run only on the server, are never shipped to the browser, and may fetch data directly instead of going…
- RSCSIBM's software for moving spool files between VM mainframes — and so the engine underneath both VNET and BITNET.
- RSIDThe flavour of the SID file format for C64 tunes that only play correctly on a fully emulated Commodore 64.
- RspackByteDance, 2023 — a Rust implementation of webpack with the same plugin API. 10× faster on large projects without ditching…
- RSpecThe Ruby test framework that established the BDD-style describe / it / expect syntax many others (Jest, Vitest, Jasmine)…
- RSS (Receive Side Scaling) (Receive Side Scaling)The network card's way of spreading incoming packets across several receive queues, so that one CPU core doesn't have to…
- RSS (web feed) (Really Simple Syndication)XML format for subscribing to a site's updates — blogs, podcasts, news.
- rstartX11R6's protocol and tool for starting an X program on another machine in a way that let it actually find its way back to…
- RSTPRapid Spanning Tree Protocol (802.1w, 2001). Replacement for original STP (802.1D, 1990). Convergence 1-3 sec instead of…
- rsyncUnix tool for incremental file sync. Andrew Tridgell, 1996. The delta-transfer algorithm only sends changed parts of files ⇒…
- RT CoreDedicated hardware for ray-tracing acceleration in Nvidia GPU. Turing (RTX 20 series, 2018) introduced. Computes…
- RTASReal-Time AudioSuite — the Pro Tools plugin format for effects running on the computer's own CPU, as opposed to TDM, which…
- RtAudioA small C++ library offering one audio API on top of ASIO, WASAPI, Core Audio, ALSA, JACK and PulseAudio.
- RTGS (real-time gross settlement)The central bank system in which payments between banks settle one by one, immediately and with finality, in central bank…
- RTL (Siemens tiled window manager)The first tiling window manager for X, out of Siemens' research lab in Princeton in 1988, which laid windows out without…
- RTP-MIDIMIDI messages wrapped in RTP over UDP, so that two computers or synths can play together across an ordinary network.
- RTTYTeleprinting over radio — the teleprinter's characters encoded as frequency-shifting tones, the backbone of weather reports…
- RTTY artPictures made from teleprinter characters and swapped between radio amateurs on punched tape — the ancestor of ASCII art…
- Rubber BandAn open C++ library for time-stretching and pitch shifting, and the default choice for free audio software that needs either.
- Rubber vectorA rotating 3D object in which each line trails slightly behind the one above it, so the shape wobbles like jelly.
- Rubber-hose cryptanalysisA tongue-in-cheek name for getting a key out of the person who knows it, instead of breaking the cipher.
- RubrikBackup company that worked out the best sales pitch for backups wasn't disk failure but ransomware.
- RubyYukihiro "Matz" Matsumoto, 1995. Design principle: "optimized for programmer happiness". Dynamically typed, everything is an…
- Ruby on RailsWeb framework in Ruby, released 2004. Defined modern web development: convention over configuration, ActiveRecord…
- RuckusEnterprise Wi-Fi brand known for antenna technology that steers the signal to where the client is rather than shouting in…
- Rule of fiveIf a class needs its own destructor it almost certainly also needs its own copy constructor, copy assignment and — since…
- Rule of zeroThe better answer to the rule of five: design classes so they need none of the five at all.
- RumbleCanadian YouTube competitor — went from small-creator platform to "free speech" positioning, grew with conservative creators…
- Runa SandvikNorwegian security researcher known for Tor, for hacking a networked sniper rifle and for protecting journalists.
- RunbookStep-by-step instructions for handling a specific incident or operations task.
- runcThe reference implementation of the OCI runtime — the small Go binary that actually calls Linux syscalls (clone, namespaces…
- Running key cipherA Vigenère cipher whose key is a long passage of text, usually from a book, so the key never repeats.
- Running statusMIDI's compression trick: leave out the status byte when it matches the previous message, and let the receiver assume it…
- RunPodGPU cloud that rents graphics cards by the second — both cheap community nodes and serverless inference endpoints for AI…
- RuntimeThe environment that runs your code — handles memory, threads, I/O, garbage collection.
- Runtime errorError that occurs during execution, not at compile time. Common types: NullPointerException, division by zero, TypeError…
- Runway MLAI tooling for video artists — generative video, motion brush, green screen without green screen, frame interpolation. New…
- rusersA Unix command that asks the machines on the local network who is logged in, using Sun RPC and the rpc.rusersd daemon.
- Russ HousleyThe man whose name sits in the header of a surprising share of the internet's security standards.
- Russell ImpagliazzoUC San Diego complexity theorist who sorted every possible universe into five, according to how much cryptography can be…
- RustSystems language with memory safety without GC — Graydon Hoare at Mozilla, 2010, v1.0 in 2015. "Stop writing C++."
- Rust borrow checkerThe Rust compiler component that enforces ownership + lifetime rules: one mutable XOR many immutable references, all…
- RVO (Reciprocal Velocity Obstacles)Local collision avoidance where each agent takes half the responsibility for dodging, so two who meet don't wobble.
- rwallwall over the network: a command that put a message on every terminal of another machine — or of a whole group of machines…
- rwhoThe BSD command that showed who was logged in on every machine on the local network — because every machine announced it.
- RWKV"Receptance Weighted Key Value" — architecture that trains in parallel like a transformer but runs as an RNN at inference…
- rxvtThe lightweight X terminal that threw out everything xterm was dragging along, and which, as rxvt-unicode, is still the…
- Ryan AckroydLulzSec's most technically capable member posed as a teenage girl — and turned out to be a former British soldier.
- Ryan ClearyA British teenager whose botnet and IRC servers gave LulzSec its muscle, and whom the group itself called only "mildly…
- Ryan LackeyAmerican cypherpunk who in 2000 co-founded HavenCo, a data haven on a disused anti-aircraft fort in the North Sea.
- Ryan SleeviThe Google engineer who was the loudest voice when browsers started punishing sloppy certificate authorities.
- RyzenAMD's consumer CPU family — the comeback that forced Intel to start competing again.
S
- <slot> elementThe mechanism in web components for letting outside content be "projected" into set places inside a component's Shadow DOM…
- 6GThe next mobile generation, planned for around 2030 — still research, and already subject to the same overselling as 5G.
- Apache SolrDistributed search engine built on Apache Lucene — Yonik Seeley (CNET), 2004. Donated to ASF in 2006. The first large-scale…
- AWS SageMakerAWS's ML platform — data labelling, training jobs, hyperparameter tuning, model registry, deployment, monitoring in one…
- AWS SNS (Simple Notification Service)Pub-sub fan-out — publish to a topic; AWS delivers to all subscribers (SQS queues, Lambda, HTTP, SMS, email, mobile push).
- AWS SQS (Simple Queue Service)The world's oldest managed message queue — launched 2004, AWS's third service ever. Producer sends to a queue, a consumer…
- AWS Step FunctionsServerless workflow orchestrator — define state machines in JSON/YAML; AWS runs them with built-in retry, parallel, choice…
- BPDUBridge Protocol Data Unit — the messages switches exchange to run the Spanning Tree Protocol. By sending BPDUs they agree on…
- Claude SonnetAnthropic's middle-tier model. Sonnet 4.6 (2026) is the latest. Optimal balance performance/price: ~$3/M input, $15/M…
- CSS scroll snapA CSS feature that makes scrolling "snap" to set points — like a carousel that lands neatly on each image, or a page-by-page…
- ECH (Encrypted Client Hello)TLS 1.3 extension that encrypts the SNI field (hostname) in ClientHello. Default ClientHello is plaintext → ISP/middleboxes…
- GNU ScreenThe original terminal multiplexer — lets you detach from a session and find it still running when you log back in.
- IBM System/360The machine family that invented backward compatibility — and whose instruction set still runs the banks sixty years on.
- iframe sandboxHTML5 attribute on <iframe> that drastically restricts what embedded content may do. <iframe sandbox> = max-restrictive (no…
- React Server ComponentsReact feature: components rendered only on server, send HTML output to client, never run JS in browser. Launched in Next.js…
- S-boxThe lookup table that makes a cipher nonlinear — and that modern designers prefer to keep out of memory.
- S/PDIFSony/Philips Digital Interface — the consumer link that carries digital stereo from CD players and computers to amplifiers…
- S3 (Simple Storage Service)AWS's object storage — cheap, massively scalable, "read/write via HTTP".
- S3 GraphicsThe graphics chip maker inside nearly every budget PC of the 1990s, which left behind the texture compression games still…
- S3M formatScream Tracker 3's module format, which gave the PC scene more channels and effects than the Amiga's MOD and became a bridge…
- S4U2ProxyThe Kerberos extension implementing constrained delegation: a service requests a ticket to another service in the user's…
- SAA1099Philips' six-channel stereo sound chip from the mid-1980s — the heart of the Game Blaster card and of the SAM Coupé home…
- SaaS (Software as a Service)Software running in the cloud, accessed via browser, customer pays a subscription. Salesforce pioneered ~1999. Today the…
- SACKSelective Acknowledgment — TCP option (RFC 2018, 1996) that lets the receiver tell exactly which packets it received, not…
- SafariApple's browser. Launched 2003 for macOS, 2007 for iOS. Built on WebKit (forked from KHTML, KDE project). The only browser…
- Safe areaThe part of the screen guaranteed not to be obscured by a notch, rounded corners or the system's own elements.
- SAFERA 1993 block cipher built to run fast in software, and a good example of how the key schedule can become the problem.
- SAFER+A 1998 block cipher that competed for AES, lost, and then lived on in billions of Bluetooth devices.
- safetensorsSafe file format for ML model weights — replacing the unsafe pickle-based .pt/.bin.
- SagaPattern for distributed transactions — instead of 2PC, run a sequence of local transactions and define compensating actions…
- Saga compensationThe pattern of undoing a multi-step, distributed transaction (a "saga") by running explicit compensating actions for each…
- Saga patternA long-running transaction broken into a series of local steps, each with a compensating action if something goes wrong. For…
- SageBritish maker of accounting software for small businesses — one of the few European software companies in the heavier weight…
- SailPointIdentity governance: the software that finally explains why the 2019 intern still has write access to payroll.
- Sal StolfoThe Columbia professor who had machine learning hunting for intrusions long before anyone called it AI security.
- Salamis TabletA marble slab from ancient Greece where pebbles on engraved lines did the addition — the oldest surviving counting board.
- SalesforceThe company that invented SaaS as a business model and then bought half the industry with the proceeds.
- Salil VadhanHarvard professor working where pseudorandomness, zero-knowledge and differential privacy meet, and trying to make the…
- Salsa20A stream cipher by Daniel J. Bernstein from 2005, built from addition, rotation and XOR.
- SaltA random string added to a password before hashing so two identical passwords don't produce the same hash.
- SaltStackConfiguration management in Python — Thomas Hatch, 2011, acquired by VMware in 2020 (now Broadcom). Famous for speed…
- Salvatore SanfilippoWrote Redis to fix a performance problem in his own startup — and thereby gave the web its default cache.
- SAM (speech synthesizer)A speech synthesizer done entirely in software from 1982 — the robot voice that became the home computer's standard sound…
- SAM CoupéA British home computer from 1989, pitched as an upgraded ZX Spectrum — a technical hit but a commercial latecomer.
- SambaFree implementation of the SMB protocol that lets Linux and Unix servers share files with Windows.
- SambaNova SystemsStanford-rooted AI chip company betting on dataflow architecture rather than the GPU's thousands of parallel threads.
- Same-Origin Policy (SOP)Browser security rule: a page can only read data from the same "origin" (same scheme + host + port). Prevents a malicious…
- SameSite cookieCookie attribute that controls when the cookie is sent for cross-site requests. Strict = never cross-site, Lax = on…
- SAMLXML-based protocol for Single Sign-On in enterprises — Okta, Azure AD, OneLogin, Ping.
- Sample and holdA circuit that measures a voltage at one instant and then holds exactly that value until the next measurement, whatever the…
- Sample Dump Standard (SDS)The 1986 MIDI protocol for moving audio samples between samplers and computers, one patient byte at a time.
- Sample loopingTwo markers inside a sample that make the sampler repeat a middle section for as long as the key is held.
- Sample rateHow many times per second an analogue audio signal is measured when it is turned into numbers.
- Sample rate conversionRecomputing audio from one sample rate to another — trivial on paper, and a classic source of audible junk in practice.
- SamplerAn instrument that plays back recorded sound instead of synthesising it — each key triggers a recording, pitched to the…
- Sampling (Decoding)How a language model picks the next token from the probability distribution it computed. The model is deterministic…
- SamsungA South Korean conglomerate that began by trading dried fish and noodles and grew into the world's largest memory maker.
- Samsung FoundrySouth Korea's leading foundry — second largest after TSMC. Manufactures Samsung Exynos, Qualcomm Snapdragon variants, Nvidia…
- Samsung GalaxySamsung's Android line, launched in 2009, that made the company the world's largest smartphone maker.
- Samsung KnoxSamsung's hardware-rooted security platform on Galaxy devices since 2013 — with an e-fuse you can't reset.
- Samsung SDSThe Samsung group's in-house IT department spun out as a company – the one running the systems behind the phones, the…
- Samuel MorlandThe diplomat and spy who built calculating machines that left the carry to the user's own hand — a deliberate cheat in the…
- Samy KamkarThe hacker whose 2005 MySpace worm earned him over a million friends in under a day, plus a criminal conviction.
- SAN (Storage Area Network)A dedicated network giving servers access to storage at the block level. The server sees a LUN as if it were a local disk…
- SandboxAn isolated environment where code runs without being able to affect the rest of the system.
- Sandbox escapeVulnerability letting code break out of its sandbox — e.g. browser → OS, container → host.
- SandboxingRunning code in a heavily constrained environment where it can reach only what it absolutely must. The starting assumption…
- SandForceThe controller firm whose DuraWrite compression made SSDs faster for free — as long as your data actually squeezed.
- SanDiskThe flash memory company whose name was, for decades, printed on the card in your camera and the USB stick in your pocket.
- Sandpiper NetworksA California company that ran a CDN before Akamai had launched one — and that history mostly remembers as a footnote to…
- Sandwich attackA boomerang variant that slips a thin middle layer between the cipher's two halves, and used it to break KASUMI on an…
- SANEScanner Access Now Easy — an open standard API for image scanners on Unix-like systems, the Unix world's answer to TWAIN.
- SanityNorwegian headless CMS with a fully customisable React-based studio + its own query language GROQ. Real-time collaboration…
- SanminaAmerican EMS specialist in hard-to-build, regulated electronics — medical, defense, optical.
- SanyoA Japanese electronics giant that for decades made everything from televisions to rechargeable batteries, before being…
- SAPEurope's largest software company — the enterprise system that runs inventory, finance and production across much of the…
- SapphireThe window manager for the PERQ workstation under CMU's Accent, written by Brad Myers in 1983 and remembered for its…
- Sapphire TechnologyThe Hong Kong maker that has been AMD's primary Radeon add-in board partner since 2001.
- Sarah FlanneryIrish schoolgirl who in 1999 unveiled a faster alternative to RSA – and then explained why it didn't hold up.
- Sarah GordonAmerican security researcher who did something unusual in the 1990s: she asked virus writers why they did it.
- Sarah MeiklejohnThe cryptographer who showed Bitcoin is pseudonymous, not anonymous — by buying things and following the money.
- SAS (Serial Attached SCSI)The enterprise world's counterpart to SATA. Same connector size, entirely different ambition: dual ports per drive, longer…
- SAS driveSerial Attached SCSI — an enterprise interface for drives in servers and storage systems. Faster and more robust than SATA…
- SAS InstituteThe North Carolina analytics giant that never went public — and lost one of software's most consequential copyright cases.
- SASE (Secure Access Service Edge)A Gartner-coined architecture that merges networking and security into a cloud service at the edge instead of a firewall at…
- Sass (SCSS)CSS preprocessor with variables, nesting, mixins, functions — compiles to plain CSS.
- SAST (Static Application Security Testing)Security analysis of source code — without running the program. Catches common vulnerability patterns.
- SAT-based cryptanalysisTranslating a cipher into an enormous Boolean formula and letting a SAT solver go looking for the key.
- SATASerial ATA — dominant consumer disk interface since 2003. SATA3 (6 Gb/s) standard since 2009. Mainstream HDDs + 2.5" SSDs…
- SATA ExpressA failed transitional standard (~2013) that was supposed to move SATA disk storage onto PCIe via a clumsy dual connector. It…
- Satellite internetConnectivity via satellite rather than cable — and a technology that only became usable once the satellites moved closer.
- Satoshi NakamotoThe pseudonym that published Bitcoin, disappeared after two years, and left behind a million untouched bitcoin.
- SAUCEThe 128-byte metadata record scene artists appended to their ANSI and ASCII works to sign them.
- Save gameWriting down exactly enough of the game world's state to rebuild it later — and not a byte more.
- Save-set (X11)The list of other clients' windows an X client wants to outlive it — the reason a crashing window manager doesn't drag every…
- Save-under (X11)A window attribute asking the X server to keep the pixels beneath a short-lived window, so whatever was there can be…
- SavepointA named point within a transaction that you can roll back to — without aborting the whole transaction. It enables partial…
- SawfishA window manager that was really a Lisp program with window management as a side effect, and GNOME's default around the turn…
- SBC (Bluetooth codec)The mandatory audio codec in Bluetooth A2DP — simple enough for a cheap earbud chip, and therefore the one every device is…
- SBOM (Software Bill of Materials)Software Bill of Materials — a complete "inventory" of all the components and dependencies in a piece of software. When a…
- SCA virusThe first known Amiga virus, released in 1987 — a bootblock virus that spread on floppies and showed an almost friendly…
- ScaffoldingAuto-generated starter code — directories, config files, base classes. Modern counterpart to boilerplate but produced by a…
- ScalaJVM language that blends functional + OO. Martin Odersky, EPFL, 2004. Influential type system design. Big city: Twitter…
- Scala (tuning format)The .scl text format that became the common language microtonal synths use to describe a scale.
- Scale AIThe company that sells the human labour behind machine learning: labelled images, ranked answers and checked examples.
- Scale2x (EPX)A rule-based upscaler for pixel graphics that doubles the resolution and rounds off the staircases — without inventing a…
- ScaleformMiddleware that ran Flash files inside game engines, so menus and HUDs could be built by artists rather than programmers.
- ScalewayFrench cloud provider — EU sovereignty outside US/CN jurisdiction, data centres in Paris, Amsterdam, Warsaw.
- Scan chainWiring all of a chip's flip-flops into one long shift register used only during test. Without it a modern chip cannot be…
- Scanline renderingBuilding the image one horizontal row at a time, tracking which polygons cross that row.
- ScanoutThe process by which the display controller reads the framebuffer row by row and streams it to the monitor at its refresh…
- ScantronThe reader that turned the fill-in-the-bubble multiple-choice test into an American institution — grading in a second what…
- SCC (Konami)Konami's wavetable chip that smuggled extra sound channels into MSX games through the cartridge itself.
- SCD (Slowly Changing Dimension)A pattern for handling dimension data in a data warehouse changing over time. Described by Ralph Kimball and one of the…
- Scene chartsThe top lists in diskmags where the scene ranked its own best groups, coders, musicians, graphicians and swappers.
- Scene graphA tree of nodes where each node's transform is relative to its parent — move the parent and everything beneath it follows.
- Scene musicElectronic music composed using tracker software and limited sound hardware — distributed at scene parties and on disk…
- Scene partyLarge youth festivals in the 1980s–90s where demoscene programmers, musicians, and artists gathered to compete and share…
- Scene releaseA piece of software or media packaged by the warez scene's strict rules — a standardised directory name, an NFO file…
- Scene.orgThe demoscene's central file archive and home of the annual Scene.org Awards.
- ScenerAn active member of the demoscene — coder, graphician, musician or swapper — known by their handle rather than their name.
- SceneTree (Godot)Godot's main loop, and the tree of nodes that everything in a running game hangs from.
- SchedulerThe kernel component deciding which process runs next, and for how long.
- Schema (database)The structure of a database — which tables, columns, types, constraints, relations exist.
- Schema migrationA versioned, incremental change to a database's structure, applied in a fixed order so every environment ends up on exactly…
- Schema.orgA shared vocabulary for structured data on the web, created by Google, Bing, Yahoo and Yandex in 2011.
- SchemeMinimalist Lisp dialect — Gerald Sussman + Guy Steele, MIT, 1975. Just a handful of primitives, everything else built on…
- Schickard's calculating clockThe first known mechanical calculator burned down before it was finished, and the world only found out about it three…
- Schism TrackerFree reimplementation of Impulse Tracker that stays as close to the DOS original as it possibly can.
- Schneider ElectricFrench energy and automation group whose Modicon subsidiary built the world's first PLC.
- Schneier's lawAnyone can design a security system they themselves cannot break — which tells you nothing about whether anyone else can.
- SCI (Sierra Creative Interpreter)Sierra's adventure game engine from 1988 to the late 1990s, a bytecode interpreter that let the same game run on PC, Amiga…
- sci.*Usenet's science hierarchy — where researchers argued in public with each other, and with anyone who had a modem and a…
- SCIM (System for Cross-domain Identity Management)Standard protocol for automatically provisioning/deprovisioning users across systems. "When I hire someone in Workday →…
- SciPyPython's scientific computing library, built on top of NumPy. Started in 2001 by Travis Oliphant, Pearu Peterson and Eric…
- Scissor testThe GPU stage that throws away every fragment outside a given rectangle before it is drawn — cheaper than rendering…
- SCO GroupThe Unix vendor best remembered for suing IBM over Linux — and for losing the argument about who owned Unix in the first…
- ScoopWindows package manager for developers — doesn't require admin (installs in user home), focused on CLI tools (git, nodejs…
- ScoopexOne of the Amiga scene's oldest and longest-lived demo groups, founded in 1988 and still active well into the 2000s.
- ScopeWhere in the code a variable is visible — block scope, function scope, global scope.
- ScorewriterSoftware for writing, engraving and printing sheet music — the word processor of the score.
- Scott FluhrerThe Cisco cryptographer whose initial comes first in the FMS attack, the paper that turned WEP into a textbook example of…
- Scott HelmeBritish web security researcher who turned HTTP security headers into something you get a grade for.
- Scott StornettaThe physicist who, with Stuart Haber, built the first blockchain in 1991 — to prove when a document existed, not to move…
- Scott VanstoneCanadian mathematician who took elliptic curve cryptography from journal paper to phones, smart cards and standards.
- scp"Secure copy" — Unix command for file transfer over SSH. scp file user@host:/path. OpenSSH 9 (2022) marked it deprecated due…
- SCRAMSalted Challenge Response Authentication Mechanism. SASL standard (RFC 5802, 2010). Client proves it knows the password…
- ScratchProgramming as jigsaw pieces that only snap together when they fit, making syntax errors physically impossible.
- Scream TrackerThe PC scene's breakthrough tracker — Future Crew's music tool that gave the world the S3M format.
- Screen HoldingsThe Kyoto company that washes the wafer between every step — and that once took its name from the printing trade.
- Screen readerDoes not read the screen but the accessibility tree — which is why a beautiful page can still be unusable.
- Screen scrapingExtracting data from an interface built for eyes rather than programs — always a workaround, often a permanent one.
- Screen shakeThe camera jolts for a few frames on hits and explosions to lend blows a sense of weight.
- Screen shareShare your screen (full screen, specific window or browser tab) live in a call. Standard since TeamViewer 2005; modern…
- Screen spaceThe last stop on the transform chain: coordinates in actual pixels on the render target, plus a depth value as a souvenir of…
- Screen space reflections (SSR)Faking reflections by marching rays through the depth and colour buffers and reusing already-rendered pixels, instead of…
- Screen-door transparencyFaking translucency by drawing only some of the pixels, so the background shows through the gaps like through an insect…
- Screen-space errorHow many pixels a simplified model would deviate from the original on screen — the metric most LOD systems pick levels by.
- Screenshot cultureThe habit of taking screenshots of posts, messages, and stories to save, prove, or spread them — often outside their…
- ScriptableObjectUnity's class for data that lives as its own file in the project rather than as a component on a game object.
- Scroll registerA hardware register in old graphics chips that slides the visible window over a larger background, so the picture scrolls…
- Scroll-driven animationsCSS animations driven by scroll position rather than time — without a line of JavaScript.
- ScrollerThe horizontal ribbon of scrolling text at the foot of every demo and cracktro — the carrier of greetings, boasts and greets.
- ScrumThe most popular agile framework — 2-week sprints, daily standups, retrospectives, scrum master.
- scryptA key derivation function from 2009 by Colin Percival, originally for the Tarsnap backup service. The first one deliberately…
- SCUMMScript Creation Utility for Maniac Mansion — the scripting language and engine behind almost every LucasArts adventure for a…
- ScwmThe Scheme Constraints Window Manager, an X11 window manager configured in Scheme that let windows stay tied together…
- ScyllaDBDrop-in reimplementation of Cassandra in C++ with a shard-per-core architecture — 5–10× lower latency and higher throughput…
- ScytaleA rod and a leather strip from Sparta: possibly the oldest transposition cipher on record, with a key measured in diameter.
- SD card (Secure Digital)Removable flash memory card — standard since 1999, comes in the sub-formats SD, miniSD (extinct), microSD.
- SD-WANSoftware-Defined WAN — an abstraction layer that manages multiple physical WAN links (MPLS, internet, 4G/5G) as one logical…
- SD2IECA small microcontroller that pretends to be a Commodore disk drive and reads D64 images off an SD card.
- SDDMSimple Desktop Display Manager: the login screen KDE Plasma has used since 2014, where the whole look is a QML theme and…
- SDF Public Access UNIX SystemA public Unix machine from 1987 that still hands out shell accounts as if the web never happened.
- SDK (Software Development Kit)A ready-made code kit for integrating with a service or platform — wrappers, examples, docs.
- SDL (Simple DirectMedia Layer)A thin C library that gives games one interface to windows, keyboards, gamepads, audio and graphics across every major…
- SDLC (Software Development Life Cycle)The entire process from idea to production — requirements, design, code, test, deploy, maintenance, EOL.
- SDLT (Super DLT)Quantum's 2001 tape format that extended the DLT line with laser-guided head positioning and servo tracks on the back of the…
- se.*The Swedish Usenet hierarchy that replaced swnet.* and took its name from the country code rather than from a network.
- SEACThe first stored-program computer to actually run in the United States — built on borrowed time while the "real" machines…
- SEAdogOne of the first standalone FidoNet mailers: the program that handled the nightly mail exchange so the BBS itself didn't…
- SeagateThe drive maker that shrank the hard disk to PC size in 1980 and, forty years on, is still arguing that spinning platters…
- SEALA stream cipher by Phillip Rogaway and Don Coppersmith, tuned for fast software on 32-bit machines.
- Sealed SecretsEncrypts a Kubernetes Secret with the cluster's public key so it can be committed to Git without anyone but the cluster…
- Sealed SenderSignal feature that hides the sender even from Signal's own server. The server sees only "a message to recipient X" — not…
- SEAlinkXMODEM with a sliding window: a 1986 file transfer protocol that stopped waiting for an acknowledgement after every block.
- SealioningBad-faith rhetorical tactic: pester someone with endless "sincerely curious" questions and polite "sources, please?" until…
- Sean HeelanIrish vulnerability researcher who wrote about automatic exploit generation in 2009 and in 2025 had a language model find a…
- seccompLinux mechanism for whitelisting which syscalls a process is allowed to make — anything off the list kills the process (or…
- Second RealityFuture Crew's 1993 PC demo, routinely named one of the greatest ever made.
- Secondary indexAn index on a column other than the primary key, letting you search quickly on that attribute. "Find all users with last…
- Secondary motionMovement not driven directly by a character's intent but following from it — hair swishing, a cape trailing, a pouch…
- Secret (K8s)A Kubernetes object for sensitive configuration — passwords, API keys, certificates. It works like a ConfigMap but is…
- Secret managementSecurely store and distribute API keys, database passwords, certificates — and rotate them regularly.
- Secret rotationRegularly replacing secrets — passwords, API keys, certificates, database credentials — so that a leaked secret is only…
- Secret sharingSplit a key into five parts where any three reconstruct it — and any two reveal nothing at all.
- Secrets and LiesBruce Schneier's 2000 book in which the author of Applied Cryptography more or less concedes that the maths was never the…
- Secrets in codeWhen sensitive data — API keys, passwords, tokens, private keys — is checked into the source code or version history. A…
- Secrets managerA central service for secret storage + distribution + rotation. Replaces hardcoded passwords in config files. HashiCorp…
- SectigoOne of the world's largest commercial certificate authorities, formerly known as Comodo CA.
- Sector interleaveNumbering the sectors around a track out of order so a slow controller gets a breath between two reads.
- Sector slippingHandling a defective sector by skipping over it and shifting every following sector one step forward, so the numbering stays…
- SectraA Swedish company doing two things that don't seem to belong together: encrypted phones for the EU and NATO, and imaging…
- SecuniaA Danish company that collected, verified and summarised other people's vulnerabilities – and nagged users to patch.
- Secure BootUEFI feature that verifies bootloader signatures before execution. Prevents bootkits/rootkits from hijacking the boot…
- Secure by designPhilosophy: security is built into the architecture from the start, not bolted on afterwards.
- Secure cookieCookie with the Secure attribute is sent only over HTTPS. Browser drops it on HTTP requests. Protection against MITM that…
- Secure elementA tamper-resistant chip that stores keys and performs cryptography in isolation from the host operating system.
- Secure EnclaveApple's on-chip co-processor that stores and uses cryptographic keys — the main CPU never sees the key material, only…
- SecureDropFree software that lets sources hand documents to newsrooms anonymously over Tor, without the newsroom itself knowing who…
- SecureworksThe Atlanta security firm that Dell bought, took public and eventually sold on to Sophos.
- Security championA developer within a product team who takes extra responsibility for security — a bridge between the central security team…
- SECURITY extension (X11)X11's belated attempt to separate trusted clients from untrusted ones, and the reason ssh -X and ssh -Y are not the same…
- Security GroupStateful firewall at the instance level in AWS — allow-only rules for inbound/outbound traffic. Attached to ENIs (EC2, RDS…
- Security headersHTTP headers that harden websites — CSP, HSTS, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, Permissions-Policy.
- Security levelA measure, in bits, of how much work the best known attack takes — 128-bit security means roughly 2¹²⁸ operations.
- Security misconfigurationWhen systems, frameworks, or cloud services are insecurely configured — default passwords left in place, unnecessary…
- Security theaterMeasures that make people feel safer without actually making them safer.
- Security through obscurityRelying on nobody knowing how the system works — which holds up right until somebody takes it apart.
- sed (Stream editor)Unix tool for text transformations line-by-line via scripts. Lee McMahon, Bell Labs, 1973. sed 's/foo/bar/g' file.txt is the…
- Seed phraseTwelve or twenty-four words that are the entire wallet — whoever has the words has the money, regardless of who bought it.
- Seek timeHow long a hard drive's arm takes to reach the right track — the number that shaped forty years of systems design.
- SEEN-BYLines at the end of an echomail message listing every node that had already received it, so nobody sent it there again.
- SegaBegan with coin-op machines on American military bases in Japan, ended as a games publisher after losing the console war.
- Sega Mega DriveThe sixteen-bit console that took on Nintendo with attitude, faster hardware and a hedgehog.
- Sega Super ScalerSega's mid-1980s line of arcade boards that scaled sprites in hardware, faking three dimensions until polygons caught up.
- Segment Routing (SR, SRv6)Modern source routing — the sender determines the entire path through a list of "segments" in the packet header, instead of…
- Segmentation fault (segfault)Posix signal SIGSEGV — the program tried to access memory it isn't allowed to read/write. Most common cause of crashes in…
- seismoA computer at a seismology research centre in Virginia that accidentally became one of Usenet's most important hubs — and…
- SekaA bare-bones 68000 assembler from the mid-1980s that became the first generation of Amiga sceners' tool of choice — more…
- SelectionRequest and SelectionNotifyThe pair of events behind every copy and paste on X11: a question to whoever owns the selection, and an answer saying where…
- Selective hydrationHydrate (bind JS to) only the parts of the page that need interactivity — in the order the user touches them.
- Selectron tubeThe memory tube the IAS machine was designed around, and which failed to arrive on time.
- SeleniumThe original for browser automation — controls a real browser via the WebDriver protocol. Selenium IDE (record/playback)…
- Self-attentionMechanism where each token in a sequence "looks at" every other token and decides how much weight to give them — the heart…
- Self-clocking codeAn encoding that carries its own clock inside the data stream, so the receiver can recover timing without a separate clock…
- Self-consistencyA technique that runs the same question several times with random variation (sampling), gets several independent reasoning…
- Self-demagnetizationA magnetised medium builds an internal field that fights itself — the wall that stopped longitudinal recording.
- Self-modifying codeA program that rewrites its own instructions as it runs — on the first stored-program machines a necessity, not a dirty…
- Self-PlayAn AI agent plays against itself to improve — classic RL technique. AlphaGo Zero (2017) made it iconic. Now: LLMs use…
- Self-Rewarding LLMLLM acts as both generator AND reward model on its own outputs — used for iterative DPO without human raters. Meta paper…
- Self-signed certA TLS certificate signed by itself instead of a CA — browsers show a warning.
- Self-synchronizing stream cipherA stream cipher that finds its keystream again on its own after bits have been lost.
- SELinux (Security-Enhanced Linux)Mandatory access control in the Linux kernel, developed by the NSA and merged in 2003. Every process and file gets a label…
- Semantic chunkingSplitting a document at points where the topic actually shifts, instead of at a fixed character limit. It measures the…
- Semantic HTMLUsing HTML elements for their meaning, not their look: <article>, <nav>, <button> instead of divs everywhere.
- Semantic searchSearch based on meaning instead of exact words — "how do I fix my car" finds documents on "automotive repair".
- Semantic securityThe requirement that a ciphertext reveals nothing about its plaintext, not merely that the key is hard to guess.
- Semantics (programming)What a program means, what it does when it runs. Distinct from syntax (what it looks like). Three formal approaches to…
- SemaphoreSynchronisation primitive that allows N threads at once — a generalisation of a mutex (where N=1).
- SemgrepStatic analysis tool where rules are written as "code patterns" instead of AST graphs — $X.execute($SQL) matches SQL…
- Semi-implicit EulerA simple integrator that updates velocity first and then uses the new velocity for position — a small change that makes it…
- SemtechThe analog company that happened to buy the French startup whose radio technology became LoRa.
- SemVer (Semantic Versioning)Version format MAJOR.MINOR.PATCH with clear semantics: 2.4.1.
- SendEvent (X11)The X11 request that lets one client hand a fabricated event to another program's window — stamped with a flag that gives…
- SendGridTransactional email API — "send order confirmations, password resets, notifications". The reason not to run your own SMTP…
- SendmailBerkeley's mail server, which delivered most of the internet's email for two decades and was infamous for its configuration…
- SenseTimeOne of the world's most valuable computer-vision companies, known for facial recognition — and for landing on the US…
- Sentence Transformers (SBERT)Python library for generating embeddings — wraps BERT-derivatives and newer models for text similarity.
- Sentence windowA RAG strategy that indexes and matches on individual sentences (high precision in the search), but then gives the model a…
- SentencePieceGoogle's 2018 tokenizer, which treats text as a raw character stream including the spaces, and therefore works the same on…
- SentinelOneCrowdStrike's closest EDR rival, selling the promise of rewinding a ransomware attack.
- SentryAn error-tracking service that collects exceptions from running software and groups them before users get round to…
- SEO (Search Engine Optimization)The work of ranking high in search results without paying for the placement. Traditionally split into technical SEO, content…
- SEPAThe Single Euro Payments Area, where a euro transfer to another country is meant to be as fast and as cheap as a domestic…
- Separating axis theorem (SAT)Two convex shapes fail to overlap if and only if there exists an axis along which their shadows do not overlap.
- SequelizeNode's oldest major ORM — Active Record style for Postgres, MySQL, MariaDB, SQLite, Microsoft SQL Server.
- SequenceA database object whose only job is to hand out the next number in order. It sits behind SERIAL and IDENTITY and is the…
- Sequence number (X11)The silent running count attached to every X request, and the only way to match an error to the call that caused it.
- Sequence parallelismSplitting activations along the sequence dimension across devices, to reach the memory that tensor parallelism cannot…
- Sequent Computer SystemsThe Oregon company that showed big servers could be built from lots of cheap microprocessors instead of one expensive one.
- Sequential consistencyA consistency model where all operations appear to occur in some single global order, and each process's operations keep…
- Sequential impulseErin Catto's iterative physics solver, which nudges the bodies' velocities one contact at a time until every constraint is…
- Serdar ArgicAn automated poster that in 1993–94 replied to every Usenet article mentioning Turkey, including the ones about the…
- Serge HumpichFrench engineer who showed in 1998 that the signing key on French bank cards could be factored on a home computer, and got a…
- Serge VaudenayCryptographer at EPFL who showed in 2002 that CBC encryption with padding can be broken through error messages.
- Sergei SkorobogatovCambridge hardware researcher who keeps demonstrating, soldering iron in hand, what vendors insist cannot be done.
- Sergey BratusResearcher who argues that most vulnerabilities are really parsing bugs, and who gave exploitation a theoretical vocabulary.
- Sergey BrinThe other half of Google — the mathematician who took Larry Page's link idea and turned it into a working search engine.
- Sergey UlasenThe Belarusian antivirus analyst who found Stuxnet in June 2010 while chasing down why an Iranian customer's machines kept…
- SerializabilityThe strictest isolation level — execution of parallel transactions yields the same result as if they were run one at a time…
- Serializable isolationStrictest transaction isolation level. Guarantees that concurrent transactions produce the same result as if run one at a…
- SerializationConverting an in-memory object to a format that can be saved/transmitted — JSON, Protobuf, XML, binary.
- Serialization failureThe error a database gives when, under SERIALIZABLE isolation, it detects that concurrent transactions can't be ordered into…
- SerpentA 1998 AES finalist that put security margin ahead of speed — and lost the competition because of it.
- Serum (synthesizer)Steve Duda's wavetable software synth, which from 2014 became the default instrument of electronic dance music.
- ServerA computer that waits for and answers requests from other computers.
- Server ActionAsync function tagged with "use server" directive — bundles never sent to client, callable from client-side via…
- Server blockingA Mastodon instance admin blocks an entire other instance — users on X can't see or be seen by users on Y. Standard…
- Server reconciliationThe netcode step where a client re-applies its still-unacknowledged inputs on top of an authoritative server state…
- Server reset (X11)What the X server traditionally does when the last client disconnects: tear down everything it has built, reinitialise and…
- Server-Sent Events (SSE)One-way real-time communication from server to browser — like WebSocket but unidirectional, over plain HTTP.
- Server-side decorationsWhen the window manager, not the application, draws the title bar, borders and close button around a window.
- ServerlessRun code without managing servers — the cloud starts an instance on demand and shuts it down.
- Service AccountIdentity for pods to authenticate against the Kubernetes API + external systems. Distinct from User Account (humans). Every…
- Service discoveryThe mechanism for how services find each other in a dynamic environment where IP addresses constantly change. Instead of…
- Service locatorA registry that hands out a service through its interface, sparing the caller from knowing or constructing the concrete…
- Service meshInfrastructure layer for microservices — handles traffic, mTLS, retries, observability between them.
- Service mesh sidecarThe proxy (usually Envoy) injected as a sidecar beside each service in a service mesh and capturing all its network traffic…
- Service workerJavaScript that runs in the background in the browser, independent of the site — powers PWAs.
- Service worker lifecycleThe phases a service worker goes through — install, activate, then active (fetch) — with a deliberate "waiting" mechanic…
- ServiceNowThe ticketing system that big-company IT departments live inside — and that most employees know only as the form where you…
- Servo trackPositioning information burned onto the platter that the head-actuator reads to stay centred on a data track.
- Servo wedgeThe wedge-shaped fields of pre-written position data embedded among the user data that keep the read head on track.
- SessionA user's ongoing interaction with a site — usually a server-side object with an ID mapped via a cookie.
- Session fixationAttack: attacker plants a known session ID in the victim's browser (via XSS, MITM, or URL parameter), waits for the victim…
- Session hijackingSteal a user's session cookie and thereby log in as them without knowing the password.
- Session keyA key that protects a single session and is discarded when it ends.
- sessionStorageBrowser API for temporary key-value storage per tab. Data is deleted when the tab closes. Distinct from localStorage…
- sessregThe small program that records an X login in utmp and wtmp so that who and last can see it — because xdm, unlike getty and…
- SetData structure that stores unique elements. Supports fast membership testing: "is x in the set?". Usually built on a hash…
- Seth SchoenThe EFF's first staff technologist, who decoded colour printers' hidden tracking dots and helped freeze encryption keys out…
- SetInputFocusThe X protocol request that decides which window the keyboard types into — and what happens when that window goes away.
- Settling timeThe time after a seek when the head is still oscillating and must stabilise over the target track before any read or write…
- Setup and hold timeThe two timing requirements on a flip-flop's input: data must be stable for a period before the clock edge and for a period…
- setxkbmapThe command that switches keyboard layout in a running X session by asking the XKB rules database for a new keymap.
- SEV-SNPAMD Secure Encrypted Virtualization - Secure Nested Paging. EPYC Milan (2021+). Adds memory-integrity protection + remote…
- Seymour CrayBuilt the world's fastest computer repeatedly across thirty years, and solved the heat problem before anyone else understood…
- SF-LOVERSThe ARPANET mailing list for science fiction fans — the first big list that had nothing to do with work.
- SFF (Small Form Factor)PC build under 20 liters volume. Mini-ITX mobo + SFX PSU + custom-fit case (NCASE M2, Dan Cases A4, Fractal Terra). Niche…
- SFINAE (Substitution Failure Is Not An Error)The C++ rule that a template which becomes invalid once the types are substituted is quietly dropped from the candidate set…
- sFlowSampled Flow — industry standard for packet sampling-based monitoring. InMon, 1999. Sends 1-in-N packet samples + interface…
- SFMLSimple and Fast Multimedia Library — a C++ library for windows, 2D graphics, audio and networking, and often the first thing…
- SFP (Small Form-factor Pluggable)A standardized pluggable transceiver for network gear. It lets the same switch port become fibre, copper or a direct-attach…
- SFT (Supervised Fine-Tuning)The first finetuning step after pre-training — train on prompt+response pairs so the model learns to follow instructions.
- SFTP (SSH File Transfer Protocol)File transfer over an SSH connection — encrypted from the first byte, no separate port.
- SFU (Selective Forwarding Unit)The server that makes group video calls viable: it takes one stream per participant and forwards it to everyone else.
- SFV fileThe little text file of CRC checksums that tells you whether a multi-part scene release downloaded whole and intact.
- SFZA plain-text format describing a sampler instrument: which audio files play for which keys and velocities, and what happens…
- SGD (Stochastic Gradient Descent)Classic neural-training optimizer: compute the gradient on a mini-batch (not the entire dataset), take a step in the…
- SGLangLLM inference server from UC Berkeley/LMSYS — challenges vLLM with RadixAttention for prefix-cache sharing and fast…
- SGX (Software Guard Extensions)Intel's hardware-based "enclaves" — encrypted memory the OS kernel itself can't read. For confidential computing and DRM (4K…
- SHA-0The original Secure Hash Algorithm, published in 1993 and withdrawn two years later without explanation.
- SHA-1The hash function the whole internet rested on for twenty years, and which took another twelve to retire after it was…
- SHA-1 is a ShamblesThe first chosen-prefix collision for SHA-1, from 2020 — the step from "theoretical worry" to "you can forge signatures with…
- SHA-2The family of SHA-224, SHA-256, SHA-384 and SHA-512, which is still the hash standard most people use.
- SHA-256Hash algorithm in the SHA-2 family — 256 bits, still secure. The de facto standard for file checksums and Bitcoin.
- SHA-3The hash function NIST standardised in 2015 as an independent alternative to SHA-2.
- SHA-512The 512-bit member of the SHA-2 family, built on 64-bit words.
- SHACALBlock ciphers built from the compression functions of SHA-1 and SHA-256, an unusual way to recycle a hash.
- shadcn/ui"Copy-paste" component library — Shad Cohen, 2023. You don't install an npm package; the CLI copies the component source…
- ShadebobsTranslucent blobs that leave smoky trails of light where they overlap — the Amiga's "bobs" drawn additively against the…
- ShaderA small program run on the GPU, once per vertex or per pixel, massively in parallel.
- Shader compilation stutterThe hitch when a PC game meets a new effect and has to compile its shader right then — in the middle of the fight.
- Shader graphVisual, node-based shader authoring where you wire nodes together instead of writing HLSL or GLSL by hand.
- Shader MinifierTool that squeezes GLSL and HLSL code into the shortest possible text, built for intros where every byte counts.
- Shader ShowdownA live-coding tournament at Revision in which two programmers write shaders from a blank screen while the crowd watches.
- Shader variantOne concrete compiled version of a shader, produced by fixing a particular combination of its compile-time keywords and…
- ShadertoyA website for writing and sharing fragment shaders that run directly in the browser.
- ShadesA British multiplayer text adventure from 1985 that ran on Micronet 800, Prestel's service for home computer owners.
- Shadow acneThe speckled, moiré-patterned blotches that appear when a surface wrongly shadows itself, because the shadow map's depth…
- Shadow banForm of moderation: an account is blocked without being told. Posts are visible to the poster themselves but not to others…
- Shadow biasThe depth offset added before the shadow-map comparison to stop surfaces from wrongly shadowing themselves.
- Shadow CredentialsAdding your own key to an account's passwordless-login attribute, then logging in as that account. More discreet than…
- Shadow DOMAn isolated DOM subtree inside an element — outside CSS and scripts can't reach into it.
- Shadow mappingShadows are produced by first rendering the scene's depth as seen from the light, then, during the normal pass, comparing…
- Shadow parts (::part())The way a web component nominates which of its internal elements may be styled from outside. An explicit contract rather…
- Shadow volumeShadows as geometry: extrude the silhouette edges away from the light into closed volumes and use the stencil buffer to…
- Shafi GoldwasserGave cryptography its proofs — before her a cipher was secure until someone broke it, after her security could be defined.
- Shai HaleviIsraeli-American cryptographer who made fully homomorphic encryption actually run and showed where the random oracle model…
- Shape extension (X11)The X11 extension that let windows be something other than rectangles — the reason xeyes exists.
- ShapecastLike a raycast, but it sweeps a whole shape — sphere, capsule or box — along a direction and returns the first hit.
- sharA file archive disguised as a shell script: run it with sh and it unpacks itself.
- SHARCAnalog Devices' family of floating-point DSPs, one of the most common chips in professional audio hardware.
- Shard keyThe column that determines which shard (database node) a row lands on in a horizontally partitioned database. The choice of…
- ShardingSplit a database across multiple servers — each shard holds a subset of the data.
- Shared expertAn expert every token passes through, in addition to the ones the router picks. It exists so the same basic knowledge…
- Shared memoryThe fastest form of inter-process communication: two processes map the same physical memory pages and read each other's data…
- shared_buffersPostgreSQL's own buffer cache in shared memory. The default is 128 MB, a leftover from when servers had a fraction of…
- SharedWorkerJS worker shared by multiple tabs/iframes from the same origin — a single instance, many clients, communication via…
- SharewareThe distribution model where the program is free to pass on and payment rests on the honour system.
- SharkeyAn actively maintained fork of Misskey that became a de facto successor when Firefish (Calckey) lost momentum. It keeps…
- SharpJapanese electronics maker named after a mechanical pencil, which took the calculator and the LCD from the lab to the pocket.
- SHAtteredThe first public SHA-1 collision: two different PDF files with the same hash, unveiled by Google and CWI Amsterdam in…
- Shebang (#!)The first two characters of an executable Unix script file: #!/usr/bin/env python3. Tells the kernel which interpreter to…
- Sheet feederThe mechanism that feeds one loose sheet of paper at a time — the opposite of the continuous tractor web.
- Sheet-fed scannerA scanner that pulls in loose sheets one at a time past a fixed sensor, rather than laying them on a glass plate.
- SheinChinese ultra-fast-fashion app — beat Zara/H&M as the world's largest fashion retailer in 2022. ~6000 new garments per day…
- Shell accountInternet access by logging in to someone else's Unix box — how most private individuals first got online.
- Shell injectionWhen unsanitised input is executed as a shell command — attackers can run arbitrary commands on the server.
- Shell scriptA program written in the shell's own language. The glue of Unix: run commands, connect them with pipes, check exit codes…
- Shell widget (Xt)The Xt widget you never see but which talks to the window manager: every top-level window, dialog and popup menu in an Xt…
- ShellshockCVE-2014-6271 in Bash. Specially crafted environment variable that begins with () { :;}; → bash executes arbitrary commands…
- Shelving filterA filter that boosts or cuts everything above or below a corner frequency by a fixed amount, so the curve levels off like a…
- Sherman FairchildThe inventor and IBM's largest shareholder whose money started Fairchild Semiconductor — and with it Silicon Valley.
- Shift JIS artJapanese text art built from kana, kanji and symbols in the Shift JIS encoding, usually just called AA.
- ShiftRowsShiftRows is the AES step that rotates the rows of the state so that the columns get mixed in the next step.
- ShimA thin layer of code that intercepts calls to an API and turns them into something the environment actually understands.
- Shimmer reverbA reverb whose tail is fed through a pitch shifter and back in, so each pass climbs an octave higher.
- Shin-EtsuThe Japanese chemicals giant that makes the actual slice of silicon everyone else's machines then work on.
- Shingled magnetic recording (SMR)Letting the write tracks overlap like roof shingles — denser data, but every rewrite tears up the neighbouring track.
- ShitpostDeliberately low-quality or absurd internet post. Often humor through contrast against the venue's norms. 4chan roots…
- Shockley Semiconductor LaboratoryThe first silicon company in what would become Silicon Valley, remembered mainly for the eight people who quit.
- Shoe-shiningWhen the host can't feed a streaming drive fast enough, the tape stops, backs up and restarts — over and over, like…
- Shoot-'Em-Up Construction Kit (SEUCK)Sensible Software's 1987 tool that let anyone build a vertical shooter on the Commodore 64 without writing a line of code.
- ShopifyE-commerce platform. Tobi Lütke (Germany → Canada), 2006. Originally built as an internal solution for a snowboard shop…
- Shor's algorithmFactors large numbers in polynomial time — and thereby renders RSA and elliptic curves unusable the day the hardware exists.
- Short CodeThe first attempt to let the programmer write the formula instead of the machine code — paid for with a fiftyfold slowdown.
- ShovelwareSoftware shovelled together into a product with no curation — sold on quantity rather than content.
- ShrinklerAn Amiga cruncher by Blueberry that squeezes executables with a context-modelling range coder — the 4k intro's favourite.
- Shuffle bagRandomness without replacement: every outcome goes into a bag, gets drawn in shuffled order, and the bag is refilled only…
- Shugart AssociatesThe floppy company that gave the world the 5¼-inch disk and the interface that became SCSI.
- ShuttleTaiwanese maker that kicked off the tiny-computer trend in 2001 with its XPC cube.
- SibeliusThe scorewriter that started life on the Acorn Archimedes and became the industry standard for composers and music…
- SiC transistorSilicon Carbide MOSFET. Wide-bandgap (3.3 eV), handles 1200V+ with low losses. Standard in modern EV-motor inverters (Tesla…
- SICP (Structure and Interpretation of Computer Programs)The textbook by Harold Abelson and Gerald Jay Sussman (1985, second edition 1996). Course book for MIT's 6.001. Known as the…
- SID chipThe sound chip in the Commodore 64 — three oscillators, ADSR, and an analog filter that sounded slightly different on every…
- SID Factory IIA modern cross-platform editor for C64 music, built by the veterans behind JCH Editor and the Vibrants player routines.
- SID filterThe analog filter in Commodore's SID chip — and the reason the same tune sounds different on two C64s.
- SID historyThe attribute that lets an account keep its old identifiers after a domain migration. Write a privileged value into it and…
- SID MusicElectronic music composed for the SID chip in the Commodore 64, a signature sound of 1980s homebrew computing and the…
- SID replacementModern chips that drop into a C64's SID socket and emulate the sound chip, since the originals are no longer made and are…
- SID tuneA piece of Commodore 64 music stored as 6502 machine code rather than recorded audio.
- SID-WizardA full-featured SID tracker by Hermit that runs on a real C64 — not a cross-editor on a PC.
- Side effectWhen a function does something beyond returning a value — writing a file, changing global state, sending a network request.
- Side-channel attackExtract secrets by measuring something that isn't the algorithm itself — time, power, EM radiation, acoustics, cache state.
- SidecarPattern: run a helper container next to your app container — for logging, proxy, mTLS, secret fetching.
- Sidecar containerA helper container that runs in the same pod as the main application and extends it with functionality — logging, a proxy…
- SidechainAn independent blockchain linked to a main chain by a bridge — faster and cheaper, but with security of its own.
- Sidechain compressionCompression where a signal other than the one being processed decides when the compressor clamps down.
- SIDPlayThe player that makes the Commodore 64's SID music listenable on modern machines by emulating the whole sound chip.
- SidStationThe first product from Gothenburg's Elektron: a MIDI-controlled synth module built around the Commodore 64's SID chip.
- Siebel SystemsThe dominant CRM vendor around the turn of the millennium – and the target when Salesforce set out to prove software could…
- SIEM (Security Information and Event Management)Central system that collects logs from everything and looks for security incidents.
- SiemensGerman conglomerate from the telegraph era whose control systems run a large share of the world's factories, which is…
- Sierra On-LineThe family business that put pictures in adventure games and got home-computer owners upgrading to see them.
- Sierra WirelessCanadian company that put mobile data into laptops long before phones could share theirs.
- SiFiveThe company RISC-V's creators started to prove you can sell cores for an open instruction set — rather like ARM, minus the…
- SIGABAThe American rotor machine with fifteen wheels, ten of which enciphered nothing at all and merely decided how the other five…
- SIGKILLSignal 9 — the only one that cannot be caught, ignored or blocked. kill -9.
- Sigma ruleA generic, vendor-neutral rule format for log detection — "YARA for logs". A Sigma rule describes a suspicious pattern in…
- SignalEnd-to-end encrypted messenger run by a non-profit — the gold standard for private communication.
- Signal (Messenger)End-to-end encrypted chat app from the non-profit Signal Foundation — the gold standard for secure communication, funded by…
- Signal FoundationThe non-profit foundation that owns the Signal messenger — founded 2018 with a $50M donation from WhatsApp co-founder Brian…
- Signal ProtocolE2EE protocol developed by Open Whisper Systems (Moxie Marlinspike, 2013). Combines X3DH for initial key exchange and Double…
- Signal StoriesSignal feature launched 2022: 24-hour ephemeral posts à la Instagram Stories. Controversially received by puristic Signal…
- Signal usernameA Signal feature (2024) that lets you be contacted via a username instead of revealing your phone number. A big privacy step…
- Signal-to-noise ratio (SNR)How much stronger the wanted signal is than the noise beneath it, expressed in decibels.
- Signals (JS)Reactive primitive: a variable that automatically notifies consumers when it changes. A modern alternative to React state.
- Signals (reactivity)A reactivity model for UI frameworks where values ("signals") automatically track which parts of the interface depend on…
- Signature block (.signature)The block of text appended to every post and email, with its own delimiter and an unwritten length limit.
- Signed distance field (SDF)A function that answers, for any point in space, how far it is to the nearest surface — positive outside, negative inside…
- SigneticsOne of the first companies to make nothing but integrated circuits, and the home of the 555 timer.
- SigNozAn open-source observability platform built on OpenTelemetry and ClickHouse — a self-hostable alternative to Datadog in a…
- SIGSALYBell Labs encrypted Churchill's and Roosevelt's phone calls with noise pressed onto gramophone records — fifty tons of…
- SigstoreOpen-source supply-chain signing — sign artifacts (containers, packages, files) with OIDC identities instead of long-lived…
- Sigstore / cosignAn open source ecosystem (Linux Foundation/OpenSSF) for signing and verifying software artifacts — container images…
- SIGTERM / SIGKILLUnix signals for stopping processes. SIGTERM = "please exit" (catchable). SIGKILL = "die now" (the kernel terminates…
- Silicon Carbide (SiC)Wide-bandgap semiconductor (3.3 eV) — perfect for high-voltage high-temperature power electronics. Drives EVs (Tesla, BYD)…
- Silicon Graphics (SGI)The dream machines of nineties 3D graphics: purple and teal workstations that rendered Hollywood's dinosaurs and cost about…
- Silicon ImageThe chip company whose signalling sits underneath DVI and HDMI, and which therefore made money on almost every flat-screen…
- Silicon LabsThe Austin company that gathered the smart home's radio protocols — Zigbee, Thread, Bluetooth and Matter — onto a single…
- Silicon MotionFabless semiconductor company that makes controllers for NAND flash — Phison's main competitor.
- Silly VentureA demoparty in Gdańsk for Atari platforms only, from the 8-bit machines to the ST and Falcon.
- Silly Window SyndromePathological TCP behaviour where the receiver advertises a few bytes of free space at a time and the sender dutifully emits…
- Silver TicketA forged Kerberos service ticket. Grants access to a single service on a single host — but never writes a line into the…
- Silvio MicaliItalian-American cryptographer who, with Shafi Goldwasser, put modern cryptography on provable foundations.
- SIM card (Subscriber Identity Module)A smart card that identifies the subscriber to the mobile network. First manufactured by Giesecke & Devrient in 1991 for…
- SIMD (Single Instruction, Multiple Data)CPU instruction that performs the same operation on multiple data elements in parallel — typically 4, 8, 16, or 32 at a time.
- SimonA family of lightweight block ciphers published by the NSA in 2013, alongside Speck.
- Simon SinghBritish science writer whose book The Code Book talked a generation into breaking ciphers.
- Simon's algorithmA quantum algorithm that finds a hidden XOR period in a function exponentially faster than any classical method.
- Simple power analysisReading secrets from a single power trace, by eye rather than by statistics.
- Simplex noiseKen Perlin's 2001 redesign of his own gradient noise, built on a simplex grid that scales better to high dimensions and…
- SimplygonSwedish middleware that generates the coarser LOD versions of 3D models automatically, so artists don't have to build them…
- Simson GarfinkelAmerican security researcher and author whose career runs from Unix handbooks through second-hand hard drives to the…
- SimtelA software archive on an army computer in the New Mexico desert that was, for about a decade, where you got your DOS…
- SimulaA Norwegian simulation language from 1967 that happened to invent classes, objects and inheritance — that is, object…
- Simulation islandA group of bodies that touch or constrain one another and so must be solved together — separate islands are solved, and put…
- Sinc interpolationThe theoretically perfect way to compute values between the samples of a band-limited signal, and the thing every serious…
- SinchThe Swedish company behind a good share of the one-time codes landing on your phone, even though almost nobody has heard of…
- Sinclair ResearchClive Sinclair's company, which made computers cheap enough for British bedrooms and then bet the farm on an electric…
- SingleStore (previously MemSQL)In-memory distributed SQL database — HTAP (Hybrid Transactional/Analytical Processing). MemSQL rebranded to SingleStore in…
- SingletonDesign pattern: ensure a class has just one instance in the entire program.
- Singleton componentAn ECS component that exists exactly once in the whole world and holds the global state that belongs to no particular entity.
- Singleton patternGang-of-Four pattern — ensure a class has exactly one instance and give global access to it. Famously an anti-pattern as…
- SingularityContainers for supercomputers, built on the premise that researchers must never become root.
- SIPThe protocol that sets up and tears down calls over IP — the signalling, not the audio.
- Sir DysticThe cDc member who wrote Back Orifice, the remote-control tool that showed how little Windows 98 defended itself.
- SisenseIsraeli BI platform whose columnar "ElastiCube" engine promised to crunch large datasets on ordinary servers, no separate…
- SiteGroundBulgarian host that WordPress officially recommends — and that is just as famous for its renewal prices.
- SitemapXML file listing all URLs on your site — helps search engines (Google, Bing) discover content. Standard since 2005 (Google…
- SiteopThe person who ran a warez topsite — the internet age's sysop, with power over affiliations, quotas and who got in.
- SIV (Synthetic Initialization Vector)An AEAD mode that derives its IV from the message itself, so a repeated nonce does not completely destroy security.
- SixelDEC's raster format in which every character carries six pixels stacked vertically — bitmaps that travel down a plain text…
- SizecodingThe art of fitting image, music and motion into a few kilobytes — or a few hundred bytes — of code.
- SK hynixMemory's eternal number two, promoted to number one because AI needed stacked DRAM.
- Skaffold"npm run dev" for Kubernetes — watches files, builds an image, deploys to your local cluster, streams logs.
- SkavenPeter Hajba's handle — a Future Crew musician and artist who later ended up at Remedy.
- SkeinA hash function submitted to the 2008 SHA-3 competition that reached the final round but did not win.
- Skeletal animationA technique in which a visible surface is deformed by an invisible hierarchy of bones, so animators move bones instead of…
- Skeleton KeyPatching a domain controller's memory so that one master password works for every account in the domain — while everyone's…
- SketchMac-exclusive design tool for UI/UX. Pieter Omvlee + Emanuel Sá, Bohemian Coding (Netherlands), 2010. Pioneer of…
- SketchpadIvan Sutherland's 1963 doctoral thesis: a drawing program that invented computer graphics and the idea of pointing at what…
- Skid RowAn Amiga-era cracking group whose name was picked up by a later generation of PC crackers and became shorthand for broken…
- Skin weightsThe numbers that decide how much each bone influences a vertex — normalized to sum to one and usually capped at four bones…
- Skip listProbabilistic data structure — a sorted linked list with "expresses" at higher levels that let you skip past elements. O(log…
- SKIP LOCKEDA SQL clause (FOR UPDATE SKIP LOCKED) that, when row-locking, skips rows already locked by another transaction instead of…
- Skip scanAn optimization technique where the database can use a composite index even if the query lacks a condition on the index's…
- SkipjackThe NSA's secret block cipher inside the Clipper chip, with a 64-bit block and an 80-bit key.
- SkyboxA textured cube drawn around the entire scene to fake a distant horizon and sky.
- SkypeVoIP pioneer from 2003 — Estonian-Swedish founding team (Niklas Zennström, Janus Friis), built on top of P2P architecture…
- SkyscannerScottish flight meta search engine — started 2002 in Edinburgh by Gareth Williams (ex-Rolls-Royce). Trip.com Group (Chinese…
- SkyworksQorvo's twin rival in radio front-ends, and one of the suppliers most dependent on Apple.
- sl (Steam Locomotive)An ASCII steam train that chugs across your terminal when you type sl instead of ls.
- SLA (Service Level Agreement)Contractual promise about a service's uptime/performance — break it and the customer gets compensation.
- SLAAC (Stateless Address Autoconfiguration)IPv6's way of letting a machine give itself a valid address by listening to what the router says, with no server involved at…
- Slab allocatorThe kernel's allocator for small, frequently recurring objects — it caches ready-made inodes and network buffers instead of…
- Slab methodThe fast test for whether a ray hits an axis-aligned box: intersect it with three pairs of parallel planes and compare the…
- SlackWorkplace chat launched in 2013 by Stewart Butterfield (after his game studio crashed and the team had internally built a…
- Slack HuddleSlack feature for spontaneous voice calls inside a channel or DM. Launched 2021 as a lightweight alternative to Zoom…
- Slapback echoA single short echo of roughly 70–180 milliseconds with no feedback — the signature sound of rockabilly.
- Slash commandText commands that start with a slash (/) and trigger an action in a chat app — /giphy, /remind, /poll. The bridge between…
- Slashdot ("News for nerds")Ancient tech news forum — the precursor to Reddit and Hacker News, still going.
- Slashdot effectA small site gets linked from a large forum and collapses under the traffic within minutes. Named after Slashdot, which was…
- SLAY RadioA round-the-clock station for Commodore 64 remixes, where 1980s game music gets rearranged with modern instruments.
- SLCSingle-Level Cell — NAND flash with 1 bit per cell (on/off). Fastest + longest life (~100k erase cycles) + most…
- SLC cacheA portion of a TLC/QLC SSD temporarily run in fast SLC mode (1 bit per cell) to absorb writes at high speed. Explains why…
- Sleep obfuscationEncrypting your own code in memory while lying dormant and decrypting it right before waking up. Aimed at scanners that…
- Sleeping bodiesHow a physics engine stops paying for objects that are just lying there.
- SlerpInterpolating between two orientations along the shortest arc on the quaternion sphere, at a steady angular velocity the…
- SLESSUSE Linux Enterprise Server — the German distribution's paid, long-term-supported server edition.
- Slew limiterA module that caps how fast a control voltage is allowed to change, turning jumps into ramps.
- SLI (Service Level Indicator)An actual measured metric: "fraction of HTTP requests under 500 ms", "error rate", "uptime".
- Slide attackA cryptanalytic attack that exploits identical rounds under one key in a block cipher.
- Slide ruleTwo logarithmic scales sliding past each other, turning multiplication into the addition of lengths.
- Slider (read/write head)The tiny air-foil block at the end of the actuator arm that carries the read and write elements and flies nanometres above…
- SlideshowDemo format consisting of a sequence of static images or graphics with music and transition effects, used when real-time…
- Sliding-window attentionA form of sparse attention where each token only gets to look at a fixed number of nearest preceding tokens (a sliding…
- SLiMSimple Login Manager: a small, themeable login box for X with no desktop dependencies, the lightweight distributions'…
- SLIPThe simplest conceivable way to push IP packets down a serial line — so simple it barely qualifies as a protocol.
- SLO (Service Level Objective)Internal target for an SLI: "99.5% of requests must be < 300 ms over a month".
- SLO / SLIThe foundational concepts in SRE for measuring and targeting reliability. An SLI is an actual metric (e.g. the fraction of…
- slockThe suckless screen locker: a single-colour screen with no input box, which changes colour as you type and turns red when…
- Slope collisionHandling movement along angled ground in platformers — keeping the character grounded on a hill, projecting velocity along…
- Sloppy quorumA variant of quorum where a write is accepted by any N available nodes — not necessarily the N that "own" the data — when…
- Slot mapA container that stores elements densely yet hands out stable handles of an index plus a generation counter, so a stale…
- Slow query logLogging every query that takes longer than a set threshold. The fastest route from "the database feels slow" to a concrete…
- SlowlorisA low-bandwidth DoS — open lots of HTTP connections and send headers very slowly, one byte at a time. The web server…
- Slowly Changing Dimension (SCD)A data-warehouse pattern for handling dimension data that changes over time — e.g. a customer who moves. The question is…
- slrnA terminal Usenet reader from 1994, built on the S-Lang library and beloved by people who read far more than they posted.
- SLSA (Supply-chain Levels for Software Artifacts)Supply-chain Levels for Software Artifacts (pronounced "salsa") — a framework from Google/OpenSSF for incrementally…
- SMAAA post-process anti-aliasing that reads an image's edge patterns morphologically and softens them, with better quality than…
- smailA simpler Unix mail server, built to spare admins Sendmail's config file — and to find a way through the UUCP maze.
- Small cellA short-range base station filling in where the big masts fall short — on lampposts, in ceilings, in tunnels.
- Small subgroup attackAn attack on Diffie–Hellman where the attacker sends a public key of small order and reads off the private key piece by…
- SmalltalkThe language that defined object orientation. Developed at Xerox PARC by Alan Kay, Dan Ingalls and Adele Goldberg through…
- Smart Access Memory (SAM)AMD's brand name for Resizable BAR — the feature that lets the CPU address all of the graphics card's memory (VRAM) at once…
- Smart contractCode that lives on a blockchain and is executed by every node when someone calls it. The term was coined by Nick Szabo in…
- SmartCard-HSMA smart card from Germany's CardContact that does most of what an HSM does, at a fraction of the price, on a chip the size…
- SmartNICA network card that can be programmed to do part of the packet processing itself instead of merely delivering bytes to the…
- SmartsheetProject management that looks like a spreadsheet — rows, columns and Gantt views for everyone who already thinks in cells…
- SmartThingsSamsung's smart-home platform — a 2012 Kickstarter hit that Samsung bought two years later.
- SMAUGThe MUD engine behind Realms of Despair, which let builders create the world from inside the game without touching the…
- SMB (Server Message Block)Windows' protocol for file and printer sharing — what sits behind every \\server\share.
- SMICChina's largest contract chipmaker, and the main target of Western export controls.
- Smishing (SMS phishing)Phishing over SMS — "your parcel couldn't be delivered, click to reschedule", "your bank detected unusual activity, verify…
- Smoke testThe fastest possible test: does the system start at all, or does it smoke?
- Smooth scrollingScrolling a pixel at a time instead of jumping a whole tile, so the world glides past evenly.
- smproxyX11R6's session proxy: a program that connects to the session manager on behalf of every window whose owner never learned…
- SMPTE ST 2110The family of standards moving professional TV production off SDI cabling and onto ordinary IP networks, with video, audio…
- SMPTE timecodeHours, minutes, seconds and frames — the address that gives every frame in a production a unique name.
- SMS (Short Message Service)Text messages over the mobile network. The first SMS was sent in December 1992 ("Merry Christmas"). Max 160 characters (GSM…
- SMT (Simultaneous Multi-Threading / Hyper-Threading)A physical CPU core appears as two (or more) "logical" cores — switches between threads when one stalls on a cache miss or…
- SMT disable (security)Disabling Simultaneous Multi-Threading (Intel Hyper-Threading, AMD SMT) as a mitigation against side-channel attacks (L1TF…
- SMT threadA logical thread created by Simultaneous Multi-Threading (Intel's Hyper-Threading), where a single physical core runs…
- SMTP (Simple Mail Transfer Protocol)The protocol for sending email — IMAP/POP3 are for reading, SMTP is for sending.
- Smurf attackDDoS technique from the 90s: spoof the victim's IP, send ICMP echo request to broadcast addresses → all machines on the…
- SN76489Texas Instruments sound generator with three square-wave channels that gave the TI-99, ColecoVision, Sega and BBC Micro…
- SNA (Intel)Chris Wilson's acceleration layer for Intel's X driver: faster than anything before it, and so intricate that only he really…
- Snap (Snapcraft)Canonical's universal Linux package format. 2014. Containerized apps (squashfs + AppArmor confinement) that can run on any…
- Snap MapSnapchat's map that shows where your friends are in real time via Bitmoji avatars. Launched 2017. Heatmap of Snaps…
- SnapchatEphemeral photo/video messages — Evan Spiegel and others, 2011. Introduced two formative concepts: ephemeral content…
- Snapchat streakSnapchat mechanic: two users who send snaps to each other every day build a "streak" — counter + 🔥 emoji next to the name…
- SnapperSUSE's filesystem-snapshot tool that makes a bad update undoable — roll back straight from the boot menu.
- Snapshot interpolationThe client draws the world a fraction of a second in the past, interpolating between two server snapshots so motion stays…
- Snapshot isolationTransaction isolation level where each transaction sees a consistent snapshot of the database from its start time — no read…
- SNDHThe Atari ST scene's chiptune archive: files carrying the games' own replay code so an emulated YM2149 recreates the music.
- sndioOpenBSD's audio and MIDI framework, built on the principle that less code means fewer bugs.
- SneakernetTransferring data by walking it over — enormous bandwidth, catastrophic latency.
- SnefruA 1990 hash function designed by Ralph Merkle at Xerox PARC and named after the Egyptian pharaoh Sneferu.
- SNI routingServer Name Indication — TLS extension that lets client specify hostname in ClientHello (before TLS handshake completes)…
- SNKThe arcade maker whose Neo Geo let you take home the exact same game that stood in the bar — at a price to match.
- SNMP (Simple Network Management Protocol)Classic protocol for monitoring network hardware — switches, routers, UPS, printers.
- SNMP trapsSNMP push notifications from agent to manager when events occur (interface down, threshold breach, auth fail). UDP 162…
- SNOWA family of stream ciphers from Lund that ended up in mobile networks, protecting traffic in UMTS and LTE.
- SnowflakeCloud data warehouse built from scratch for the cloud — Benoit Dageville, Thierry Cruanes, Marcin Zukowski, 2012. Separates…
- Snowflake IDTwitter-invented distributed unique ID generation technique (2010). 64-bit integer: 41 bits timestamp + 10 bits worker ID +…
- Snowflake schemaA variant of the star schema where dimension tables are normalized into several levels — e.g. product → category →…
- SnykIsraeli security platform — open-source dependency scanning, container scanning, IaC scanning, SAST. Founded 2015.
- SO_REUSEPORTSocket option that lets several processes bind the exact same port, after which the kernel itself distributes incoming…
- SO-DIMMSmall Outline DIMM — compact RAM form factor for laptops, NUC mini-PCs, some servers. ~50% smaller area than desktop DIMM…
- SOAP (Simple Object Access Protocol)XML-based protocol for web services. Dominated enterprise integration in the early 2000s before REST took over. Still alive…
- SOAR (Security Orchestration, Automation and Response)Automate SOC work — on alert: run the playbook (block IP, isolate host, gather evidence, open ticket).
- SoCSystem on Chip — all major components (CPU, GPU, RAM controller, modem, NPU, IO) on one die. Standard in mobile phones since…
- SoC (System-on-Chip)A chip that integrates nearly the entire computer system — CPU, GPU, memory controller, NPU, modem, I/O — onto a single…
- SOC 2An audit standard (AICPA) where an independent auditor reviews and attests that a company's internal security controls…
- soc.*Usenet's hierarchy for society, culture and religion — where the net first discovered that people from different countries…
- socat (SOcket CAT)Connects two arbitrary data channels and pipes everything arriving on one out through the other. Netcat with ten times more…
- Social engineeringHacking people instead of systems — manipulating them into giving out information or doing something.
- Social graphNetwork structure of relationships between users: friends (mutual), followers (asymmetric), mutuals, second-degree…
- SocketThe programming interface for network traffic — an endpoint you read from and write to like a file.
- Socket AM5AMD's desktop CPU socket since 2022 — LGA 1718 (1718 pins, the first LGA socket on AMD desktop), used by Ryzen…
- Socket.IOReal-time events between browser and Node — not WebSocket, but its own protocol that uses WebSocket when it can.
- SockpuppetA fake extra account a person uses to pretend to be someone else — to agree with themselves, evade a ban, manipulate votes…
- SOCKS proxyGeneric proxy protocol — works for any TCP/UDP traffic, not just HTTP.
- SOCKS5Proxy protocol. RFC 1928 (1996). Application-agnostic — proxies TCP (and v5 also UDP). Distinct from HTTP proxy (HTTP only)…
- Soft bodyA body that deforms under force instead of holding a fixed shape — cloth, jelly, rubber — the opposite of a rigid body.
- Soft deleteMarking a row as deleted instead of removing it — typically a deleted_at timestamp. Gives you a trash bin, undo and the…
- Soft launchHinting at a new relationship on social media without revealing the partner — a hand in frame, a shadow, two plates of food…
- Soft particlesFading a particle's transparency where it cuts into solid scene geometry, so smoke and fog melt into the floor instead of…
- Soft shadowsShadows with soft, blurred edges instead of razor-sharp ones — an imitation of the penumbra a real light with area produces.
- Soft-sectored diskA floppy with a single index hole, where the controller works out where each sector begins from address marks in the data…
- SoftBankThe Japanese software distributor that became a telecom giant and then the world's most dramatic venture capitalist.
- SoftcodeCode players write from inside the game on a MUSH, as opposed to hardcode compiled into the server.
- SoftHSMAn HSM made of pure software: the same PKCS#11 interface as a real module, but the keys sit in ordinary files.
- SoftPOSAn ordinary smartphone accepting contactless card payments through its own NFC antenna, no extra card reader required.
- Software AGGermany's second-largest software house for decades, built on a mainframe database still running in systems nobody dares…
- Software ArtsThe company that wrote VisiCalc, the first spreadsheet for personal computers and the reason plenty of businesses bought an…
- Software RAIDRAID implemented in OS kernel instead of dedicated hardware controller. Linux mdadm, ZFS, Btrfs, Windows Storage Spaces…
- Software renderingRendering where the CPU computes every pixel itself and writes it into video memory, with no graphics card involved.
- Software spriteA moving object the CPU draws into video memory itself, pixel by pixel, because there is no video chip to do it.
- SointuModular software synth for 4k intros that grew out of 4klang and was rebuilt for modern tooling and more platforms.
- SoitecA French company whose "Smart Cut" splits silicon into atom-thin layers — and that sits in the radio front-end of nearly…
- SoketiOpen-source WebSocket server that speaks Pusher's protocol, so it can replace Pusher Channels without touching the client…
- Solar DesignerRussian security developer behind the John the Ripper password cracker and the first public return-to-libc attack.
- Solar Realms EliteSpace strategy door game from 1990 in which BBS users built empires and attacked each other a few turns a day.
- Solar2DThe Lua engine formerly known as Corona SDK, which outlived its own company and carried on as open source.
- SolarisSun's Unix for servers — home to several technologies the rest of the industry first mocked and then copied.
- SolarWinds OrionDecember 2020 — Russian SVR (APT29 / Cozy Bear) trojaned SolarWinds Orion update server, distributed Sunburst malware to…
- Soldered IHS (sTIM)When the CPU manufacturer solders the heat spreader (IHS) to the silicon die with an indium-based solder (sTIM) instead of…
- SOLIDFive OOP principles from Robert Martin: Single responsibility, Open/closed, Liskov substitution, Interface segregation…
- Solid ink printerThe printer fed with wax crayons: ink is melted, jetted onto a spinning drum, and transferred to paper in a single pass.
- SolidityThe language smart contracts on Ethereum are written in — syntactically familiar, semantically unforgiving.
- SolidJSA framework that looks like React — JSX, components, hook-like primitives — but works entirely differently underneath. No…
- SolidStartOfficial meta-framework for SolidJS. Ryan Carniato team. Stable November 2024 after 2+ years in beta. File-based routing…
- Solitaire cipherA stream cipher run with an ordinary deck of cards, designed by Bruce Schneier for Neal Stephenson's novel Cryptonomicon.
- Solomon KullbackCodebreaker from Friedman's first intake who later lent his name to the Kullback–Leibler divergence.
- SolskogenA Norwegian summer demoparty running since 2002, notable for the fact that people actually go outside.
- Solver islandA group of physics bodies linked by contacts or joints that must be solved together, while disjoint groups can be solved…
- Something AwfulComedy site and forum from 1999 where an account cost ten dollars. The fee paid for the servers and doubled as a tax on…
- Son of 1036Henry Spencer's 1994 draft of a new Usenet standard — never adopted, yet for fifteen years the document every news program…
- SonarSourceSwiss company whose SonarQube is the reason your pull request has a red "Quality Gate failed".
- SonatypeThe company that runs Maven Central, and so has its hand on the tap for much of the Java world's dependencies.
- Song Position PointerThe MIDI message that tells a drum machine where in the song to start, so nobody has to sit through the intro every time.
- Sonic PiA coding environment where you write music in a Ruby-flavoured language and hear the change the moment you hit Run — built…
- SonicWallThe firewall box that became the small office's default choice long before security was a boardroom topic.
- SonoBusAn open-source app for playing music together over the internet, where each participant sends audio directly to the others…
- SonosThe company that invented wireless multi-room audio for the home — and taught its customers how much a speaker depends on an…
- SonyFrom a transistor radio in a bombed-out Tokyo building to the image sensor in your phone — with the Walkman, the CD and the…
- Sony EricssonThe joint venture in which Japanese consumer electronics was supposed to rescue Swedish mobile phones, and for a few years…
- Sony PCM-F1A portable PCM adaptor that turned digital audio into a video signal, so an ordinary VCR became a digital audio recorder.
- SophosAn Oxfordshire antivirus firm that went after corporate customers while Norton and McAfee fought over home PCs.
- SOPSSecrets OPerationS — encrypts only the values in a YAML/JSON/INI file and leaves the structure cleartext, so the whole file…
- SoraOpenAI's video-generating model — shocked the world in February 2024 with 60-second 1080p clips from text prompts.
- Sorting algorithmA method for ordering elements by a comparison rule — the most thoroughly studied problem in all of computer science.
- SosemanukAn eSTREAM stream cipher that borrowed from both SNOW and Serpent and quickly became one of the most admired candidates.
- Sound BlasterThe sound card that made the PC audible — and whose name was printed on the back of every game box for a decade.
- Sound cardThe expansion card that gave the PC something better to say than a beep.
- Sound ForgeThe Windows classic among waveform editors: one file at a time, edited down to the sample, from Sonic Foundry in the early…
- Sound trendAn audio clip (a song snippet, line of dialogue, or sound effect) that becomes a template for thousands of videos on…
- SoundCloudYouTube for audio — DJ mixes, demos, podcasts, the "SoundCloud rap" phenomenon of 2015–2018.
- SoundFontA file format that bundles recorded instrument samples with the rules for playing them, so a MIDI file can sound like real…
- SoundmonitorChris Hülsbeck's music program for the Commodore 64, published in 1986 as a type-in listing in the German magazine 64'er and…
- Source 2Valve's current game engine, successor to Source — first in Dota 2 in 2015, later Half-Life: Alyx and Counter-Strike 2.
- Source EngineValve's game engine, which arrived in 2004 with Half-Life 2 — remembered for physics, facial animation and a modding…
- Source mapFile that maps minified/transpiled JS back to the original source. Lets the debugger show your TypeScript/JSX instead of…
- Source separation (music)Splitting a finished stereo mix back into vocals, drums, bass and everything else, without access to the original tracks.
- SourcefireThe company built around Snort, the open-source intrusion detection system.
- SourceForgeThe first big free host for open-source projects — home to thousands of them before GitHub, and later squandered its…
- SourcegraphCode-search platform that lets developers search, navigate and bulk-edit across every codebase a company owns at once.
- SourceHutA minimalist software forge with not a line of JavaScript, built around email: git send-email, patch lists and CI instead of…
- SoX (Sound eXchange)The Swiss Army knife of audio on the command line: converts, resamples and applies effects, one pipe at a time.
- SoyjakThe Wojak variant with an open mouth, wide eyes and a thin beard, used to mock somebody for being enthusiastic about the…
- SPA (Single-Page Application)A web app that loads once and updates via JavaScript instead of fetching new pages.
- Space amplificationWhen the database uses more disk space than the logical dataset actually requires. In LSM trees this is due to old…
- Space colonizationProcedural algorithm that grows branching structures — trees, roots, blood vessels — by letting branches creep toward…
- Space InvadersThe game that started the arcade's golden age — and whose most famous mechanic was a bug that was allowed to stay.
- SpaceballsNorwegian demo group behind State of the Art, and the crew that put the Nordic Amiga scene on the map.
- Spaces (macOS)Apple's virtual desktops, which arrived with Mac OS X Leopard in 2007 — twenty years after the idea had been fully worked…
- Spacewar!The first computer game to spread: two spaceships, a star with gravity, and all the spare machine time at MIT.
- Spacing lossThe read signal dies exponentially with the gap between head and medium — about 55 dB per wavelength.
- SPAN (network)NASA's network for space physicists, built on DECnet rather than TCP/IP and thus a parallel world alongside the early…
- Span bufferA software renderer's way of solving visibility one scanline at a time: each polygon is cut into horizontal runs, and only…
- SPAN portSwitched Port ANalyzer — Cisco term for port mirroring. Switch copies traffic from source port(s) to destination port where…
- SpannerGoogle's globally distributed SQL database. Externally consistent, ACID across multiple datacenters. TrueTime: GPS + atomic…
- Spanner TrueTimeGoogle Spanner's clock API that gives the time as an uncertainty interval [earliest, latest] instead of a single number…
- Spanning Tree Protocol (STP)An L2 protocol (Radia Perlman, 1985, IEEE 802.1D) that prevents loops in switched networks by logically blocking redundant…
- SpansionAMD and Fujitsu's joint flash venture, once the largest NOR maker in the world.
- Spare sectorExtra sectors a disk holds in reserve to replace ones found defective, keeping the address space looking whole from outside.
- Spark printerA non-impact printer that burns away a thin metal film with electric sparks to reveal a black backing.
- SPARQLQuery language for RDF (Resource Description Framework). W3C standard 2008. Drives the semantic web + knowledge graphs…
- Sparse attentionAttention variants that let each token look at only a subset of the other tokens, instead of all of them — to break full…
- Sparse modelsOnly part of the network activates per input — saves compute. Mixture-of-Experts (MoE) is the most common form in modern…
- Sparse setA data structure pairing a dense value array with a sparse index array, giving O(1) insert, remove and membership test plus…
- Sparse voxel octree (SVO)An octree that stores only the occupied parts of a voxelised scene, so empty space costs no memory and high resolutions…
- Spatial audioHow a game engine places sounds in the world, so a footstep seems to come from a particular direction and distance.
- Spatial hashingCarving space into a uniform grid and hashing each cell's coordinate into a hash table, so only objects in the same or…
- Spatial partitioningDividing space into regions so a query examines only nearby objects instead of all of them.
- spawnCreate a new process as a child of the current one. Node.js child_process.spawn() is the classic implementation. Different…
- SPC700The Super Nintendo's dedicated audio processor — a Sony chip with eight sampled channels and hardware echo that defined 90s…
- SPD hubA small circuit on DDR5 modules that stores and relays the memory's information (SPD — Serial Presence Detect): timings…
- Speaker diarization"Who spoke when?" — segment audio and assign each segment to a specific speaker without knowing the speakers in advance.
- Spear phishingTargeted phishing at a specific person — research first, personalised content, much higher success than mass phishing.
- Spec-driven development (SDD)Workflow where the spec/requirements document is the primary artifact — code is generated from it with AI assistance…
- SpeckA lightweight block cipher published by the NSA in 2013, controversial for its origin and thin design rationale.
- Spectral leakageEnergy from a single frequency smeared across its neighbours in an FFT, because the analysis only ever sees a short…
- Spectral subtractionThe classic noise reduction method: measure the noise spectrum during a pause, then subtract it from every frame of the…
- SpectreClass of CPU vulnerabilities (CVE-2017-5753/5715, Jan 2018) that abuse branch prediction and speculative execution to leak…
- SpectrogramA picture of sound: time along one axis, frequency along the other, and loudness as colour.
- SpectrumThe radio frequencies available — a finite natural resource that states auction off for billions.
- Spectrum analyzerA measuring tool that shows how much energy a signal has in each frequency band — in audio, almost always an FFT redrawn…
- spectrwmA small tiling window manager from the OpenBSD crowd that wanted dwm's simplicity without recompiling for every setting.
- Specular aliasingThe flicker in specular highlights that appears when a surface carries more normal detail than pixels — the glint "boils"…
- Specular mappingA texture that dials specular highlight strength per texel, letting one surface be wet-shiny in the cracks and dry-matte on…
- Specular-glossinessThe older PBR workflow that drives a surface with a diffuse color, a specular RGB color and a glossiness channel — more…
- Speculation Rules APIA modern API (Chrome) for declaratively telling the browser which pages to preload or even pre-render (prerender) in the…
- Speculative contactsA way to stop fast objects tunnelling through walls: create contact constraints ahead of time for pairs that might collide…
- Speculative decodingLLM inference technique: small draft model generates N tokens forward, large model verifies batch in parallel. Accept if…
- Speculative executionWhen a CPU guesses which way the code will go (e.g. the outcome of a condition) and starts executing instructions ahead of…
- Speech recognitionTurning sound waves into text — a problem declared almost solved roughly every twenty years since 1952.
- SpeedcodeUnrolled, address-hardcoded machine code that trades memory for cycles — no loops, just a straight run of stores.
- SpeederaA CDN that survived the dot-com crash but not Akamai's lawyers.
- SpeedlockThe fast-loading copy protection every Spectrum owner met in the '80s — rainbow stripes down the border and a countdown…
- SpeedoBitstream's outline font format and the first one X11 could scale inside the server, courtesy of a donated rasterizer and…
- SpeedrunFinishing a game as fast as possible, often by exploiting the bugs the developers never got round to fixing.
- SpeedTreeThe modelling tool and runtime library that builds, animates and LODs the trees in a startling share of games and films.
- SpeexXiph.Org's free speech codec from 2002, built for VoIP and later retired in favour of Opus.
- SpegelA stateless peer-to-peer mirror for container layers in a Kubernetes cluster: nodes fetch images from each other instead of…
- Sperry RandA gyroscope maker and a typewriter company that merged in 1955 and thereby owned UNIVAC — the first commercial computer, run…
- SPF recordSender Policy Framework — a DNS record that lists which servers are allowed to send email for a domain. Receiving servers…
- SPH (smoothed particle hydrodynamics)A method that represents a fluid as a cloud of particles, where pressure and density are computed by weighting in the…
- Sphere tracingA way to trace rays against implicit surfaces by stepping forward exactly as far as the distance field says is safe.
- Spherical harmonicsA frequency-domain basis for functions on a sphere, used in graphics to store a whole environment's low-frequency lighting…
- SPI busSerial Peripheral Interface — a fast, synchronous serial bus for connecting a microcontroller to peripherals (sensors…
- SPIFFESecure Production Identity Framework For Everyone — standard for workload identity in modern distributed systems. A SPIFFE…
- SpinFermyon's serverless framework built on WebAssembly + WASI. Functions in Rust/Go/JS/Python/TinyGo compile to Wasm, run as…
- Spin bitThe one bit in the QUIC header left unencrypted purely so that somebody in the middle can measure round-trip time. A…
- Spin-up timeThe time a spinning device needs from power-on to full speed and ready-to-read — trivial for one drive, a power problem for…
- Spindle motorThe brushless motor that spins the drive's platters at constant speed — everything else in the drive takes aim at its axis.
- Spindle runoutThe small wobble a hard disk's spindle makes as it turns — the deviation from a perfect circle that caps how tightly tracks…
- Spindle speedHow fast the platters rotate, in revolutions per minute — higher means lower latency and more throughput, but more heat and…
- SpineAn animation tool that gives 2D characters a skeleton instead of one drawing per pose.
- SpinlockA lock that waits by spinning in a loop and asking again — burning CPU instead of sleeping.
- SpinwriterNEC's letter-quality printer, which used a cup-shaped "thimble" element instead of a flat daisy wheel.
- Spiral of deathThe failure mode where a fixed-timestep loop that cannot simulate a frame in time keeps demanding more catch-up steps each…
- Spiral trackA single continuous track winding outward from the centre — optical media's answer to the hard disk's concentric rings.
- SPIRESPIFFE Runtime Environment — the reference implementation of the SPIFFE standard. CNCF Graduated 2022. Server (issues SVIDs)…
- Spirit duplicatorCopying machine that pulled up to a few hundred purple copies from a handwritten or typed master sheet — the workhorse of…
- Splash screenInitial screen shown while an app loads — logo + brand color. Hides real load time and gives a feeling of faster startup.
- SpleeterDeezer's pretrained tool that, in 2019, turned stem separation into something you could run on an ordinary laptop in seconds.
- Spline animationAnimating a value — usually an object's or camera's position — by moving it along a spline curve over time, giving smooth…
- Split horizonRouting protocol rule: don't advertise a route back over the interface you learned it from. Prevents count-to-infinity loops…
- Split knowledgeThe requirement that no single person ever knows a whole key, only one component of it.
- Split screenLocal multiplayer where the screen is carved into two to four panes and the scene is rendered once per player.
- Split-screen scrollingHolding part of the screen still — usually a status bar — while the rest scrolls, by reloading the scroll register partway…
- SplunkLogs and SIEM platform — Michael Baum, Rob Das, Erik Swan, 2003. Acquired by Cisco in 2024 for 28 BUSD. Standard in Fortune…
- SpodTalker slang for someone who spends an unreasonable amount of time logged in — a label that was insult and honour in roughly…
- SPOF (Single Point of Failure)A component whose failure brings down the whole system — the first thing to hunt for when designing for HA.
- SpoolingBuffering output to disk so a slow peripheral can be fed at its own pace without stalling the processor.
- SporgerySpam and forgery in one: drowning a newsgroup in posts bearing other people's names until the real conversation can no…
- Spot instanceCloud servers at 70-90% off — but the cloud provider can kill them with a few minutes' notice.
- SpotifySwedish music streamer that rewrote the music industry's business model — 600M+ users by 2024.
- Spotify GreenroomSpotify's Clubhouse-clone — live audio rooms. Launched June 2021 (acquired Locker Room March 2021), shut down September…
- SpotlightA point light that only shines inside a cone, with a soft edge between an inner and an outer angle.
- Spring armA camera boom that holds the camera at a distance behind a target, follows with spring-like smoothing and pulls in…
- Spring boneBones driven by a simple spring and damper so hair, tails and straps sway after the motion without full physics.
- Spring BootConvention-over-configuration on top of Spring Framework. Phil Webb + Dave Syer, 2014. Starters + auto-configuration +…
- Spring FrameworkJava framework for dependency injection + enterprise services. Rod Johnson, 2003 (after the book "J2EE Design and…
- Spring IntegrationSpring project for Enterprise Integration Patterns (Hohpe + Woolf, 2003) — message channels, transformers, routers…
- Spring jointA soft constraint that links two bodies with a spring: it pulls them toward a rest state rather than holding them rigidly.
- Spring reverbReverberation from a couple of coil springs in a metal tank, with an unmistakably boingy character.
- Spring-damperA spring (Hooke's law, stiffness k) paired with a damper (resistance proportional to velocity) — the building block of soft…
- Spring4ShellCVE-2022-22965 — RCE in Spring Framework via classloader manipulation in data binding. Java 9+ feature interaction caused…
- SpriteA small image that moves across the background without destroying it — the 1980s solution to animation without enough memory.
- Sprite batchingMerging many sprites that share a texture into a single draw call via one vertex buffer, instead of issuing a call per…
- Sprite flickerThe telltale shimmer when more sprites crowd onto one scanline than the hardware can draw, and the engine lets them take…
- Sprite maskA separate one-bit image in the shape of the sprite that punches a hole in the background before the sprite itself is…
- Sprite multiplexingReusing the C64's eight hardware sprites several times per frame to put dozens on screen at once.
- Sprite priorityThe rule that decides which hardware sprite shows when two overlap, and whether a sprite sits in front of or behind the…
- Sprite sheetA single image packing many sprites or animation frames, addressed by UV coordinates to cut texture binds and draw calls.
- Sprite stackingFakes 3D in a 2D engine by stacking many top-down sprite slices with a small vertical offset and rotating them together.
- Sprite stretchingA C64 trick that fools the VIC-II into repeating a sprite's rows down the screen, so one sprite covers a large area.
- Sprite zero hitThe NES flag that trips the instant the first sprite's pixels touch the background — a game's only clock in the middle of a…
- SpriteKitApple's built-in 2D game framework, which arrived with iOS 7 in 2013 and made most third-party engines unnecessary for…
- SpritePadA Windows editor for C64 sprites that spared people from drawing 24×21 pixels with a joystick on the real hardware.
- SPSSThe statistics package generations of social scientists learned to click through — often without being sure which test they…
- SpyderScientific Python IDE. Open source. Aimed at data science + numeric computing. Standard part of the Anaconda distribution…
- SpyglassThe company that licensed Mosaic to Microsoft and watched it become Internet Explorer – for free.
- SpywareSoftware that gathers info about you without your knowledge — keyloggers, screenshot grabbers, mic activators.
- SQL (Structured Query Language)Standard language for relational databases. Don Chamberlin + Raymond Boyce, IBM, 1974 — back then called SEQUEL. ANSI…
- SQL injectionWhen an attacker sneaks SQL code into a form and gets the database to execute it.
- SQL JOINSQL operator that combines rows from multiple tables based on a related column. INNER JOIN (only matches), LEFT/RIGHT OUTER…
- SQLAlchemyPython's most used ORM — two layers: Core (SQL expression language, query builder) and ORM (classes to tables).
- sqldServer wrapper around libSQL — turns SQLite into a network DB with an HTTP API + write replication. Turso builds its service…
- SQLGlot / SuperSQLPython library to parse, transpile, and optimise SQL between dialects — Postgres → BigQuery → DuckDB → Snowflake…
- SQLiteThe whole database in a single file — embedded in billions of apps and websites.
- SQLite FTS5SQLite full-text search extension. v5 since 2015. BM25 ranking, porter stemmer, unicode-aware. Powers local search in Apple…
- SQLite PRAGMASQLite syntax for configuring DB behavior. PRAGMA journal_mode=WAL, PRAGMA synchronous=NORMAL, PRAGMA cache_size=-64000 (64…
- SQLite R-treeSQLite spatial index extension. R-tree algorithm for 2D bounding-box queries. Since 3.8 (2014). Use: GPS data, local apps…
- SQLite WAL modeSQLite journal mode (since 3.7.0, 2010) that replaces rollback journal with write-ahead log. Allows concurrent readers + one…
- Square attackAn integral attack on byte-oriented block ciphers, named after the Square cipher it was designed for.
- Square EnixThe Japanese games company born when the two great rivals of the role-playing genre joined forces.
- SquarespacePremium website builder focused on beautiful design — favourite among photographers, artists, small businesses. Casalena…
- Squash and stretchThe animation principle of letting an object compress and extend as it moves, to convey weight, speed and life.
- Squish message baseScott Dudley's message format for Maximus — one file set per conference, instead of one file per message or one giant shared…
- SR-IOV (Single Root I/O Virtualization)A PCIe standard letting one physical card present itself as several independent devices to virtual machines.
- srcsetGive the browser several versions of the same image and let it choose — it knows things about the screen and the network…
- SRE (Site Reliability Engineering)Google's take on DevOps — operations as a software problem, focus on SLOs and error budgets.
- sRGBThe standard colour space for the web and almost everything else — limited, old, and universal precisely because of it.
- SRI InternationalThe Menlo Park research institute where the mouse was invented and which became the second node on the ARPANET.
- SRI-NICARPANET's front desk, card index and phone book — an office at the Stanford Research Institute that for two decades knew who…
- SRPSecure Remote Password — older PAKE protocol, Thomas Wu 1998. Server stores verifier (not password hash) that can't be…
- SRv6Segment Routing over IPv6 — the packet carries a list of "segment IDs" (SID) in an IPv6 header describing its path through…
- SSAO (screen-space ambient occlusion)A screen-space approximation of ambient occlusion that darkens creases and contact points from the depth buffer alone.
- SSD (Solid State Drive)Modern storage with no moving parts — flash memory instead of spinning platters.
- SSE (Server-Sent Events)Standard for server-to-client push over HTTP. Simpler than WebSockets — unidirectional (server → client), text-based…
- SSG (Static Site Generation)Generate all HTML at build time — serve just static files via CDN.
- SSGIScreen-space global illumination fakes one bounce of indirect light by tracing rays through what's already drawn on screen.
- SSH (Secure Shell)Encrypted protocol for remote-controlling servers via terminal.
- SSH keyAsymmetric key pair for logging into servers without a password — much more secure than passwords.
- SSH tunnel (Port forwarding)Send arbitrary TCP traffic through an SSH connection — bypass firewalls, reach internal services.
- SSIDThe name of a Wi-Fi network — what you see in the list when you connect.
- SSL / TLSThe protocol that encrypts traffic between client and server — what turns HTTP into HTTPS.
- SSO (Single Sign-On) (Single Sign-On)Log in once, get access to many services — "Login with Google" at enterprise scale.
- SSO (Small String Optimization) (Small String Optimization)Storing short strings directly inside the string object instead of allocating on the heap. The reason sizeof(std::string) is…
- SSR (Server-Side Rendering)When the page is rendered to HTML on the server and sent ready to the browser.
- SSRF (Server-Side Request Forgery)Server-Side Request Forgery — attacker forces server to make HTTP requests to URLs the attacker wants (often internal…
- SSTableSorted String Table — an immutable file of key-value pairs stored in sorted order on disk. The fundamental storage unit in…
- ssthreshThe boundary at which TCP stops growing its window exponentially and starts growing it linearly. The sender's running guess…
- SSTIServer-Side Template Injection — user input lands in the template engine as code instead of data, often direct RCE.
- ST NICCC 2000An Atari ST demo from 2000 that flies through a city of flat-shaded polygons at full tilt, on a machine from 1985.
- ST-01The sample disk that shipped with Ultimate Soundtracker in 1987, whose name still prefixes the instruments in thousands of…
- ST-506Seagate's 1980 hard-disk interface, which left the encoding to a controller on the host card while the drive was just heads…
- STA (Static timing analysis)Verifying that a chip meets its timing by computing every path in the design mathematically, rather than simulating it with…
- Stability AIThe London company that bankrolled Stable Diffusion and released the weights, giving the world local image generation and…
- Stable DiffusionOpen-weights text-to-image latent diffusion model — CompVis (Ludwig-Maximilians-Universität München) + Stability AI +…
- Stable Diffusion XL (SDXL)Second generation of Stability AI's open image model — 1024×1024 native, more detailed than SD 1.5.
- Stable rasterThe foundation trick that removes the jitter from a C64 raster interrupt so code lands on an exact cycle.
- StablecoinA crypto asset engineered to always be worth one dollar — which works exactly as long as the market believes it.
- StackLIFO data structure — "Last In, First Out". The last item added is the first one out.
- Stack allocatorAn allocator that hands out memory by moving a pointer forward and frees by moving a saved marker back — strictly last-in…
- Stack OverflowQuestions and answers for programmers, started in 2008 by Jeff Atwood and Joel Spolsky. Built on voting, accepted answers…
- Stack Overflow JobsDeveloper job platform built into Stack Overflow — shut down March 2022 after the Prosus acquisition ($1.8B). Pivot to…
- Stacking orderThe order in which sibling windows lie on top of one another, so the server knows which one shows where two overlap — in X11…
- Stacking window managerThe classic model where windows sit like sheets of paper on a desk, overlap, and redraw whatever gets uncovered.
- StackPathA Dallas CDN company that bought its way to scale and then watched Akamai take over its customers.
- Stafford TavaresProfessor at Queen's University in Kingston, Ontario, and the T in CAST — one of the people who turned S-box design into…
- StagingA copy of the production environment where you test before deploying for real.
- StakkatoA Swedish teenager who roamed supercomputing centres on two continents in 2004–2005 and walked off with Cisco's source code.
- stalonetrayA standalone system tray for X11, for people running a window manager with no panel but still stuck with programs that…
- Standard cellThe pre-drawn building blocks a digital chip is assembled from: gates, flip-flops and buffers, all of exactly the same…
- Standard colormaps (ICCCM)The ICCCM recipe for letting several X programs share a 256-colour colormap without asking the server about every shade: a…
- Standard MIDI File (SMF)The file format behind .mid — timestamped MIDI messages, so a sequence can move between programs and machines.
- Stanhope DemonstratorA wooden box with two sliding plates that solves syllogisms — built a century before anyone else worked out that logic could…
- Stanisław UlamWorked out over a game of solitaire that chance computes faster than combinatorics, and thereby gave ENIAC its first serious…
- Star schemaThe classic data-warehouse model: a central fact table (measures, e.g. sales) surrounded by dimension tables (time, product…
- Star Wars KidA video a fifteen-year-old in Quebec recorded of himself in 2002 and never meant to show anyone. Others posted it the…
- StarbreezeA Swedish studio that made Riddick and Payday, bet the house on VR and ended up in court-supervised reconstruction.
- StarburstCommercial distribution of the Trino query engine, founded by its creators to query the data lake without moving the data.
- StarCoderOpen code LLM from the BigCode project (Hugging Face + ServiceNow) — trained on The Stack dataset (6 TB of permissively…
- StardentThe shotgun wedding of Ardent and Stellar — two losers that together made one slightly larger loser.
- StarfieldThe demoscene's first practice effect — points flying outward from a centre to fake the illusion of space flight.
- Stargate (Usenet)A 1980s attempt to beam Usenet out by satellite, tucked inside a TV signal.
- StarlinkSpaceX's satellite internet — 7000+ satellites in low orbit, ~20–60 ms latency anywhere on the planet.
- Stars: Wonders of the WorldThe French group NoooN's PC demo that won The Party 1995 — soft, organic and a long way from the scene's cube-shaped norm.
- Start menuThe button in the corner of the taskbar that Windows 95 made the gateway to everything, so obvious that Microsoft once lost…
- Starter pack (Bluesky)Bluesky feature launched 2024: curated list of 20-150 accounts that can be shared via a link. Recipient follows all…
- StartrekkerAn Amiga tracker known for mixing sampled and FM-synthesised instruments in the same module.
- Startup notificationThe freedesktop protocol that turns the pointer into an hourglass when you click a launcher and turns it back when the…
- Startup probeA health check that gives a slow-starting container time to come up before the liveness and readiness checks take effect. It…
- State of the ArtSpaceballs' 1992 Amiga demo, famous for its dancing silhouettes moving in time with the music.
- State patternAn object changes its behaviour when its internal state changes, appearing to switch class at runtime.
- State sortingReordering draw calls so objects sharing the same shader, texture and render state are drawn together, minimising expensive…
- State synchronizationA netcode model in which the server regularly broadcasts the world's authoritative state and clients interpolate between the…
- State-space modelClass of sequence models from classical control theory that compress a sequence into a latent state vector updated step by…
- State-variable filter (SVF)A filter built from two integrators in a feedback loop, delivering lowpass, bandpass and highpass outputs at the same time…
- StatefulSetA Kubernetes object for applications that need stable identity — each pod gets an ordinal number (mysql-0, mysql-1), its own…
- StatelessA service that keeps no information in memory between requests — every call is self-contained.
- StatementA code construct that performs an action but doesn't produce a value — e.g., if, while, assignment. Opposite: expression.
- Static batchingMerging many non-moving meshes that share a material into one mesh, so the GPU draws them in a single call.
- Static bodyA physics body that never moves — infinite mass, zero velocity — meant for floors, walls and other immovable level geometry.
- Static linkingInclude all library code directly in the executable at build time. Result: one large binary that can run without external…
- Statistical saturation attackAn attack that pins part of the plaintext, lets the rest vary, and measures how lopsided a few output bits become.
- StatisticsMathematical discipline for collection, analysis, interpretation of data. Foundation for all data science + machine…
- Statistics target (default_statistics_target)How detailed a picture PostgreSQL's ANALYZE builds of a column's contents. The default of 100 is rarely enough for skewed…
- Status / presenceThe indicator showing whether someone is online, away, or busy — the green dot, "active now", custom status lines (🏖️…
- SteamBuilt to avoid asking people to download patches by hand, and became the shop PC gaming cannot get around.
- Steam DeckValve's Linux-based handheld PC — killed off the "PC gaming on the go is dead" era overnight. Has driven Proton/Linux gaming…
- Steam WorkshopValve's built-in distribution channel for user-created content, where mods, maps and items are uploaded and subscribed to…
- SteamOSValve's own Linux distribution, built to break into the living room — first a flop, then the heart of the Steam Deck.
- STECThe flash-module maker that got into enterprise storage first — and whose stock rode a rollercoaster on its customers'…
- SteckerbrettEnigma's plugboard supplied nearly all of its key space and cost almost nothing to sidestep, which says something about what…
- SteelSeriesDanish gaming-peripherals brand — mice, keyboards and Arctis headsets — founded in 2001.
- Steering behaviorsA set of simple steering forces — seek, flee, arrive, wander, avoid obstacles — combined into one movement vector for an…
- Stefan BrandsDutch cryptographer whose privacy-preserving credential technology Microsoft bought in 2008 and shipped as U-Prove.
- Stefan EsserGerman security researcher who quit PHP's security team in protest and then demonstrated why — one bug a day for a month.
- Stefan LucksGerman cryptographer in Weimar who helped build Skein and then turned to making password hashing deliberately slow.
- Stefan MangardAustrian whose Graz research group taught the world that a CPU gossips just as much as a smart card.
- Stefan SavageUC San Diego professor whose group showed that cars can be hijacked remotely and that the spam economy hinges on a handful…
- Steffen WerneryThe Chaos Computer Club's public face in the 1980s and Wau Holland's partner in the BTX hack.
- SteganographyEncryption hides the content; steganography hides the fact that there is a message at all.
- SteinbergThe Hamburg company behind Cubase — and behind VST and ASIO, two interfaces that most home studios still quietly depend on.
- Stellar ComputerArdent's mirror image on the other coast — the same graphics supercomputer, built by the man behind Prime and Apollo.
- StemsA song bounced down to a handful of submixes — drums, bass, vocals, everything else — instead of the full multitrack session.
- Stencil bufferA small integer buffer alongside the depth buffer that masks where rasterization is allowed to write, pixel by pixel.
- Step sequencerA sequencer that divides the bar into a fixed number of slots and plays whatever is in each one, in turn, on a loop.
- Stephanie ForrestThe researcher who borrowed the immune system's notion of "self versus non-self" and turned it into intrusion detection.
- Stephen CheckowaySecurity researcher who broke into cars remotely, ran ROP on a voting machine and reconstructed how Juniper's firewalls got…
- Stephen HensonThe British developer who for nearly two decades was one of a tiny handful of people actually maintaining OpenSSL.
- Stephen NorthcuttUS Navy intrusion-detection pioneer who built SANS's certification engine, GIAC.
- Stephen PohligMartin Hellman's Stanford student, whose name is on the algorithm that decides which primes are fit for discrete logarithms.
- Stephen WiesnerThe physicist who invented quantum cryptography around 1970 and then waited more than a decade for anyone to publish it.
- Stepped reckonerLeibniz's machine was the first to handle all four arithmetic operations, and the stepped gear inside it stayed in…
- Stepper motorThe open-loop mechanism that moves the head a fixed number of steps per track — simple, cheap and sensitive to heat.
- Stereo SIDA home-built mod that gives a C64 a second SID chip, and with it six voices in stereo instead of three in mono.
- Stereo widthHow far towards the sides a mix or a sound appears to extend, and the difference between the channels that controls it.
- SternTails the logs of every pod matching a pattern at once, colour-coded per pod, and automatically picks up new pods as they…
- Steve BellovinOne of the three grad students behind Usenet in 1979, who later co-wrote the book that made the firewall a household concept…
- Steve CrockerThe UCLA student who wrote RFC 1 and picked such a modest name for the series that it is still in use more than fifty years…
- Steve GibsonThe programmer who writes everything in assembly and explains security to a few hundred thousand podcast listeners every…
- Steve GoldBritish journalist who, with Robert Schifreen, read Prince Philip's Prestel mailbox and got a new law passed as a side…
- Steve Jackson GamesThe Austin game publisher whose computers the Secret Service seized in 1990 — and whose lawsuit became one of the first…
- Steve JobsDid not build the computers himself, but decided which ones got built — and what they were for.
- Steve KentThe BBN security researcher who spent four decades writing the specifications for how the internet should protect itself…
- Steve LipnerThe architect of Microsoft's Security Development Lifecycle, the process that forced security into every stage of shipping…
- Steve WozniakDesigned the Apple II essentially single-handed — with an economy of components that engineers still study.
- Steven GalbraithUniversity of Auckland mathematician who wrote the textbook on the mathematics of public-key cryptography and showed early…
- Steven LevyAmerican tech journalist who codified the hacker ethic and wrote the popular history of the Crypto Wars.
- Steven MurdochThe Cambridge researcher who proved the banks' "secure" card terminals could be talked into accepting any PIN at all.
- Stewart BakerNSA general counsel during the Crypto Wars and the Clipper chip's most outspoken defender.
- STFT (short-time Fourier transform)A Fourier transform taken over short, overlapping windows, so you learn not just which frequencies are present but when they…
- Sticker packA collection of 8-30 images/animations you can send instead of text. WebP or APNG. Telegram and LINE pushed the format big…
- Sticky session (Session affinity)The load balancer sends the same user to the same backend server every time — for session state.
- Sticky windowA window stuck to the glass of the screen, following you to every virtual desktop while the others are swapped out…
- StictionStatic friction that can weld a parked head to the platter — a classic failure of older drives that wouldn't spin up.
- Stitch (TikTok)A TikTok format where you clip a short piece (up to 5 sec) of someone else's video as the intro to your own — and then…
- STL (C++)The library that proved containers and algorithms can be fully separated — and took generic programming mainstream.
- STM formatThe module format of Scream Tracker 2 — the PC's first home-grown answer to the Amiga MOD, with the same four channels.
- STMicroelectronicsFranco-Italian chip giant, best known to developers for STM32 — the microcontroller found on half the hobbyist workbenches…
- StoneCrackerA popular Amiga cruncher that packed programs so they unpacked themselves at startup.
- Storage Access APIBrowser API where an iframe can request access to its own cookies/storage in a third-party context — the user approves via a…
- StorageClassA Kubernetes template that defines a "kind" of storage — e.g. "fast SSD" or "cheap HDD" — and how it should be dynamically…
- StorageTekStorage Technology Corporation – the company that made tape robots standard data-centre furniture.
- Stored procedureCode (in a SQL dialect) stored and executed inside the database — instead of in the application.
- Storm controlA switch feature that monitors the amount of broadcast, multicast, or unknown-unicast traffic on a port and starts dropping…
- Story highlightSaved Instagram stories pinned permanently to the profile in thematic "bubbles", instead of disappearing after 24 hours. A…
- StorybookSandbox for UI components — develop, document, and test each component in isolation from the app.
- STOSThe Atari ST's game-oriented BASIC with sprites and scrolling built in — AMOS's predecessor, from the same man.
- STP (Spanning Tree Protocol)Protocol that prevents loops in switched networks — without it, redundant links would cause broadcast storms.
- straceShows every system call a program makes, with arguments and return values. Answers "which config file does it actually…
- Straddle checkerboardA substitution cipher that writes the most common letters as one digit and the rest as two.
- Straddling checkerboardTurns letters into digits of varying length: common letters get one digit, rare ones get two.
- Strangler figA pattern for replacing an old system piece by piece instead of rewriting it all at once. Named by Martin Fowler in 2004…
- StrapiThe most popular open-source headless CMS — Node.js backend with auto-generated admin UI + REST/GraphQL API per content type.
- Strategy patternGang-of-Four pattern — define a family of algorithms, encapsulate each as a class with a shared interface, and make them…
- Stratus TechnologiesComputers with two of everything running the same instruction at once, so a dead part shows up only in a service report.
- StravaThe social network for runners and cyclists — GPS logs, segment kings, kudos.
- Stream cipherSymmetric encryption that generates a pseudo-random keystream and XORs with plaintext. Fast on short messages, no padding…
- StreamingSend media in continuous small segments instead of whole files. The receiver can start watching before everything is…
- Streaming replicationPostgreSQL's built-in physical replication: a primary server streams its WAL to one or more replicas that apply it…
- Streaming SSRThe server sends HTML in chunks as data becomes ready — instead of waiting for the whole page to be complete.
- StreamingLLMA method that lets a model generate indefinitely at constant memory, by keeping the first four tokens plus a sliding window…
- StreebogThe Russian hash function GOST R 34.11-2012, known as Streebog, with 256- and 512-bit outputs.
- Strict aliasingThe rule in C and C++ that an object may only be read through a type compatible with how it was created. Break it and the…
- STRIDEThreat modeling mnemonic: Spoofing, Tampering, Repudiation, Information Disclosure, Denial of service, Elevation of…
- Stride (game engine)A 3D game engine written in C# all the way down, core to editor — the third name for what started out as Paradox and then…
- StringA sequence of characters. What programs use for text.
- StripePayment infrastructure as an API. Founded in 2010 by brothers Patrick and John Collison. The pitch was accepting card…
- Strong consistencyEvery reader sees the latest write immediately, regardless of which replica they hit. Requires coordination — more expensive…
- Strong customer authentication (SCA)The EU rule that a payment must be confirmed with two of three factors: something you know, something you have, something…
- Structural change (ECS)When an entity's set of components changes in an ECS, its data must be moved between memory blocks — an expensive operation…
- Structural hazardWhen two instructions in the pipeline want to use the same hardware resource at once and there's only one of it — e.g. a…
- Structure of arrays (SoA)A memory layout storing each field in its own contiguous array (x[], y[], z[]) rather than an array of whole structs, for…
- Structured bindingsThe C++17 syntax auto [a, b] = expr; that unpacks a compound value into several names at once.
- Structured cloneAn algorithm (and the function structuredClone()) for making a true deep copy of complex JavaScript values — including Map…
- Structured dataMetadata that helps search engines understand the page's content — Schema.org vocabulary in JSON-LD.
- Structured outputGuaranteeing that an LLM's answer follows an exact format (usually JSON per a schema) by constraining which tokens it's…
- Structured programmingThe idea that all program logic can be built from three constructs — sequence, selection and iteration — and that goto is…
- StrudelTidalCycles' pattern language ported to JavaScript, so live-coded music runs straight in a browser tab without a Haskell…
- Struts CVE (Equifax)CVE-2017-5638 in Apache Struts 2 — RCE via OGNL expression injection in Content-Type header. Used by Equifax breach 2017…
- Stuart HaberThe cryptographer who, with Scott Stornetta, invented the linked hash chain for timestamping — 17 years before Bitcoin made…
- Stuart StanifordLead author of the paper that worked out how fast a worm could take over the internet — and was proven right the following…
- Studio monitorA loudspeaker built to expose the flaws in a mix rather than flatter it.
- Studio OnePreSonus's DAW from 2009, built by former Cubase developers with the aim that everything should work by drag and drop.
- StumbleUponA toolbar button that sent you to a random page picked to match your interests. The internet's channel-flick, from before…
- StumpWMA keyboard-driven tiling window manager written in Common Lisp that can be reprogrammed while it runs.
- STUN (Session Traversal Utilities for NAT)Protocol that helps a client behind NAT discover its public IP + port. Foundation for P2P (WebRTC, VoIP, gaming).
- Style queriesContainer queries that ask about the value of a custom CSS property rather than about width. Lets a component change…
- styled-componentsCSS-in-JS library for React. Write CSS in template literals directly in the component. Max Stoiber + Glen Maddern, 2016.
- StylelintCSS linter. PostCSS-based. 170+ built-in rules + plugin ecosystem. Supports CSS, SCSS, Less, Sugar SS. Standard for CSS…
- StytchAn API for passwordless authentication — magic links, passkeys, SMS codes — founded by former Plaid staff.
- su"Switch user" — Unix command to switch users in a terminal. Defaults to root if no target given. Requires the target user's…
- Sub-oscillatorAn extra square wave one or two octaves below the main oscillator, made by a simple frequency divider rather than an…
- Sub-tickValve's netcode model in Counter-Strike 2, where every input is timestamped between server ticks instead of being rounded to…
- SubBytesThe AES step that swaps every byte of the state for another via a fixed S-box — the only nonlinear operation in the entire…
- Subchannel (P–W)Eight bit-streams (P–W) running alongside the audio on a CD, carrying timecode, track numbers and CD-Text.
- Subclass sandboxA base class that hands out a toolbox and makes every subclass build its behaviour from those tools alone.
- Subdivision surfaceA smooth surface produced by repeatedly splitting and smoothing a coarse control mesh.
- Subdomain takeoverTakeover of a subdomain whose CNAME points to an unpaid service — the attacker registers the service and takes control.
- SubgridLets a nested grid inherit its parent's track lines instead of creating its own, so content inside separate children can…
- Sublime TextFast cross-platform text editor. Jon Skinner (Sydney), 2008. Native C++, Python plugins. Famous for fast, luxurious "Goto…
- SubmixA way station in the mix where several channels are summed onto a shared bus before they reach the main output.
- SubnetA logical division of an IP network — lets different parts have their own firewall rules and routing.
- Subnet maskA bitwise mask that splits an IPv4 address into a network part and a host part. 255.255.255.0 = /24 = 24 network bits + 8…
- Subpixel renderingExploiting the fact that each pixel consists of three coloured stripes, and thereby tripling the horizontal resolution for…
- SubredditThemed forum section on Reddit. Prefix r/. Own mod team, rules, culture. r/AskHistorians (strictly academic), r/aww (cat…
- Subresource Integrity (SRI)A browser feature that verifies an external file (e.g. a JavaScript from a CDN) hasn't been tampered with — by comparing its…
- SubroutineA block of instructions written once and called from many places — the idea that code could be reused instead of recopied.
- SubstackNewsletter + paywall + community — "blogging suddenly became lucrative again".
- SubsteppingSplitting a frame's timestep into several smaller physics steps — more but shorter steps buy stability and accuracy.
- Substitution cipherSwap each character for another according to a fixed table — and awkwardly preserve the entire statistics of the language.
- Substitution-permutation networkA design that alternates substitution and permutation over several rounds, a core building block of modern block ciphers.
- SubstructureRedirectThe X11 event mask that turns an ordinary client into a window manager: the server stops carrying out other programs' window…
- Subsurface scatteringLight that enters a translucent material, bounces around inside and exits somewhere else — what makes skin, wax and marble…
- Subtractive synthesisSound design by sculpture: start with a harmonically rich waveform and carve away what you don't want.
- SubtweetWriting a post that clearly refers to a specific person without naming or tagging them — an indirect jab. "Sub" as in…
- Subversion (SVN)Centralised version control built to replace CVS, itself replaced by Git — but still alive wherever the files are large.
- sudoUnix command that runs single commands as root or another user — instead of logging in as root.
- SugonA Chinese supercomputer builder whose machines climbed the TOP500 until Washington pulled the brake.
- SulakeThe Finnish company behind Habbo Hotel, the isometric pixel hangout of 2000s teenagers.
- Sum typeType-system feature: a type that can be one-of-several alternatives, each with own fields. Rust enum, Haskell data, Swift…
- Summary punchThe machine that punched a tabulator's totals onto fresh cards — a materialised view, fifty years before the phrase existed.
- Sumo LogicLog analytics as a cloud service, built by two ex-ArcSight engineers who reckoned Splunk should have been SaaS all along.
- Sun MicrosystemsThe company of workstations and server rooms — it gave the world Java, NFS and ZFS, and disappeared in the aftermath of the…
- SUNETSweden's shared university network, and the route by which the internet first reached the country.
- SunoThe service that turns a one-line prompt into a complete song with vocals, lyrics and a chorus — and that the record labels…
- SunSITEA network of university archives kitted out with Sun servers, where half the internet went to download software.
- SunViewThe window system on Sun workstations before X: fast, local, and blind to the network.
- SunVoxModular software synth and tracker sequencer that runs on everything from desktops to phones.
- SupabaseOpen-source alternative to Firebase — Postgres + auth + storage + realtime + edge functions in one bundle.
- Supabase RealtimeWritten in Elixir (Phoenix) — listens to the Postgres WAL (Write-Ahead Log) and broadcasts database changes as WebSocket…
- Super followA paid subscription to an individual creator for exclusive content — Twitter's/X's "Super Follows" (later "Subscriptions")…
- Super FXA RISC processor that lived inside the game cartridge and drew polygons for a Super Nintendo that was never designed to do…
- SuperblockThe filesystem's table of contents — block size, inode count, where everything starts. Without it the disk is unintelligible.
- SupercellHelsinki studio with few employees, even fewer games, and some of the most profitable mobile titles ever made.
- SuperColliderA programming language for sound synthesis, split into an interpreter that thinks and a server that makes noise, with OSC in…
- SupercomputerNot a type of machine but a position: the fastest computing resource that can be built right now.
- Superconducting qubitQubits built as electrical circuits of superconducting metal — the technology IBM and Google backed, and the most built-out…
- SuperDisk (LS-120)Imation's 120 MB diskette with laser-guided track following that could also read ordinary 1.44 MB floppies — and still lost…
- SuperdomeHP's mainframe-class server from 2000 — PA-RISC, then Itanium, now x86, and still at the heavy end of the server room.
- Supergiant GamesA small independent studio that made four acclaimed games in a row and then won big with the roguelike Hades.
- Superhuman$30/month premium email client — keyboard-first, lightning-fast, AI integration. For people who live in their inbox.
- SupermicroSold Lego to data centres for thirty years, then abruptly became an AI stock.
- Superparamagnetic limitThe point where the grains get so small that room heat randomly flips them and the data dies on its own.
- SuperpositionA quantum system being in a combination of several states at once — not "we don't know which", but genuinely both.
- SuperProbeThe XFree86 utility that guessed which graphics card you had by poking directly at its registers.
- Supersampling (SSAA)The brute-force anti-aliasing method — render the whole image at a higher resolution, then shrink it so jagged edges average…
- SupersawSeven slightly detuned sawtooth waves crammed into one oscillator — the sound that defined trance.
- SuperscalarA CPU design that can issue and execute several instructions at once within the same clock cycle, by having multiple…
- SupersedesThe Usenet header that let one article replace an earlier one — a cancel and a fresh post in a single breath.
- SuperTokensOpen-source Auth0 alternative — focused on session management, easier to self-host, cheaper at scale.
- Supervised learningML where the model is trained on labelled data — every example has a "right answer".
- Supervision treeA hierarchy of processes in Erlang/Elixir — supervisors restart child processes that crash, automatically.
- Supplier (warez)The person in a warez group who obtains the original — the risky link who leaks the software before it has even reached…
- Supply chain attackAttack via the software supply chain — backdoor in a library, compromised build server, fake update — instead of directly…
- Surface area heuristic (SAH)A cost model that chooses where to split an acceleration tree by weighing the probability a ray hits each branch against how…
- Surface cacheQuake's way of getting lit walls out of a software renderer: bake texture and lightmap together into ready-made surfaces…
- Surface codeThe leading quantum error correction code — qubits in a grid where only neighbours need to talk to each other.
- Surface netsIsosurface extraction that places one vertex per cell near the surface and joins neighbouring cells into a mesh — a dual…
- Surge XTA commercial Swedish synth that went open source and then grew faster as a community project than it ever had as a product.
- Surrogate keyA primary key with no business meaning, generated by the system — a sequence number or a UUID. The opposite is a natural key…
- SurveyMonkeyThe web's survey pioneer since 1999 — the name became shorthand for "send out a survey" long before the competition even…
- Susan HeadleyA Los Angeles phone phreak around 1980 who got passwords out of people simply by sounding like someone entitled to them.
- Susan LandauThe mathematician who became one of the weightiest voices against government backdoors in encryption.
- SUSEThe German Linux company with the green chameleon: Europe's answer to Red Hat, and owner of more owners than most…
- Sustain pedalThe foot pedal that keeps notes ringing after the keys are released — the piano's damper pedal, reduced to a switch and the…
- Sutherland–HodgmanThe algorithm that clips a polygon against a convex region by shaving off whatever lies outside one edge at a time.
- SvelteA frontend framework that compiles itself away — no runtime, super-light output.
- Svelte RunesSvelte 5's new reactivity (October 2024) — replaces the let x = 0 magic with explicit runes: $state(0), $derived(...)…
- SvelteKitSvelte's full-stack framework. Rich Harris (Svelte creator + Vercel employee). v1.0 Dec 2022. Replaces Sapper. File-system…
- Sven JaschanGerman teenager who wrote both Netsky and Sasser in 2004, and whose case was cracked by Microsoft's reward money rather than…
- SVG (Scalable Vector Graphics)XML-based image format — vector-based, scales infinitely without quality loss.
- SVGAlibThe Linux library that drew graphics straight onto the VGA card from the text console, with no X in sight, so Doom and Quake…
- SVM (Support Vector Machine)Classic classification algorithm — finds the best "separating line" between classes with maximum margin.
- SWACSEAC's West Coast sibling — for a while the fastest computer in the world, built to compute for mathematicians.
- SwaggerSpec format for REST APIs. Tony Tam (Reverb / Wordnik), 2011. Donated to SmartBear 2015 → renamed OpenAPI Specification…
- SwapDisk space used as an extension of RAM when memory runs out — slow, but better than programs dying.
- Swap chainA queue of frame buffers the GPU renders into and the display reads from, where swapping between them keeps a half-drawn…
- Swap spaceDisk space the operating system uses as an "extension" of RAM — rarely used memory pages are moved out to disk (swapped) to…
- SwapperThe scene's postal distribution arm — the member who mailed disks of cracks, demos and mags around the world before the net.
- Swayi3 for Wayland: a tiling compositor that reads i3's configuration file almost line for line, and the project wlroots was…
- SWC"Speedy Web Compiler" — Rust-based TypeScript/JavaScript compiler by Donny Wong (2017). 20× faster than Babel.
- Swedish Board for Computing MachineryThe state board tasked in 1948 with getting Sweden a computer, which solved the problem by sending a handful of young…
- Sweep and pruneA broad-phase algorithm that sorts objects' bounding boxes along each axis and only tests pairs whose intervals overlap on…
- Sweet32A 2016 attack showing that 64-bit block ciphers such as 3DES and Blowfish leak data after a few hundred gigabytes.
- Swept AABBA collision test that treats a moving box as a smeared-out volume, so fast objects can't slip through walls between two…
- SwiftApple's replacement for Objective-C — Chris Lattner (the LLVM creator), 2014, open source since 2015. Statically typed…
- SWIFT (banking network)The banks' global messaging network, which never moves a cent itself but tells everyone else where the money should go.
- Swift Package ManagerApple's built-in dependency manager for Swift — nothing to install, and integrated into Xcode since version 11.
- SwiftUIApple's declarative UI framework. Launched WWDC 2019. Replacement for UIKit (iOS) + AppKit (Mac). Inspired by React/Flutter…
- SwiGLUActivation for the transformer's feed-forward layer: Swish(xW) ⊙ (xV) — multiplies two linear projections instead of…
- SwishThe Swedish banks' joint mobile payment service, which turned a phone number into an account number and cash into a…
- SwitchNetwork device that forwards packets within a local network based on MAC addresses.
- Switch TransformerGoogle's MoE architecture from January 2021 that simplified routing down to a single expert per token — and became the first…
- SwitcherAndy Hertzfeld's 1985 utility that let a Macintosh keep several programs in memory and slide between them, one on screen at…
- swmSolbourne's window manager from around 1990, which brought the virtual desktop to X and left its name in a property programs…
- swnet.*The first Swedish Usenet hierarchy, where Swedish computer users argued in Swedish before se.* took over.
- sxhkdSimple X Hotkey Daemon: a small program that listens for key combinations and runs commands, completely decoupled from the…
- SybaseThe database company whose code became Microsoft SQL Server, and which then watched Microsoft take the market with it.
- SyftGenerates an inventory of everything that happens to be inside a container image, in one of the standard formats now…
- SymantecThe company behind Norton AntiVirus, the yellow box that came with every new PC and kept nagging you that your subscription…
- Symbian LtdThe handset makers' jointly owned operating-system company, set up to keep Microsoft off their phones.
- Symbol TechnologiesThe company that made barcode scanning handheld, invented PDF417, and was eventually swallowed by its largest competitor.
- Symbolic link (Symlink)File system pointer — file A that "is" file B. Followed transparently by most programs.
- SymbolicsThe Lisp machine company from MIT, remembered for the Genera operating system and for registering the first .com domain.
- SymfonyPHP framework from 2005, created by Fabien Potencier at SensioLabs. As much a library of standalone components as a…
- SymmetrixThe disk array with a giant cache bolted in front of the drives that let EMC muscle IBM out of mainframe storage in the…
- SYN cookieDDoS defense against SYN floods: instead of allocating a buffer for every SYN, encode all necessary handshake data in a…
- SYN cookiesDefence technique against SYN flood — instead of holding state for half-open connections, the server encodes minimal info in…
- SYN floodDoS attack where the attacker opens millions of half-open TCP connections — exhausting server resources.
- SYNC extension (X11)Counters and alarms inside the X server, so clients can wait on each other without polling.
- Sync scrollingAn Atari ST trick that fools the video chip into making scanlines longer or shorter than normal, shifting the whole screen…
- SynchronetBBS software from the early 1990s that is still being developed and now runs telnet boards as happily as it once ran dial-up…
- Synchronous commitA PostgreSQL setting that controls how strongly a COMMIT is guaranteed before the client gets an OK. Fully synchronous: wait…
- Synchronous stream cipherA stream cipher whose keystream depends only on the key and position, so sender and receiver must stay perfectly in step.
- SynclavierA digital synth from Dartmouth that grew into a complete recording studio in a rack — priced like a house.
- SyncTERMA terminal program built for calling BBSes over the internet with the right font, colours and character set.
- SynologyA Taiwanese NAS maker whose DiskStation Manager made running your own network storage server easy enough for the home.
- SynopsysOne half of the duopoly selling the software every modern chip is drawn with — no licences, no silicon.
- SynOpticsTurned Ethernet into something you could run over ordinary phone wire — and established the star topology.
- SyntaxThe rules for how source code must be shaped to be valid — what counts as a token, where semicolons go, how functions are…
- Syntax errorAn error the parser catches — code violates the language's grammar (missing paren, wrong keyword, unexpected token). The…
- SynthesizerAn instrument that builds its sound from scratch with electronics rather than playing back or amplifying something that…
- Synthetic dataTraining data generated by another model — increasingly important as the open internet runs out as a data source. Phi-3…
- Synthetic IVAn initialization vector derived from the message itself instead of being chosen at random, which makes encryption…
- Synthetic monitoringScripted "fake" users that regularly execute key flows — so you notice problems before real users do.
- SyntiantBuilds inference chips frugal enough to listen for voice commands around the clock on a coin-cell battery.
- SyQuestRemovable hard-disk cartridges of the 1980s and 90s — a detachable platter in a plastic shell, a prepress staple until Zip…
- SYS 2061The one-line BASIC stub that lets a C64 machine-code program start with a plain RUN.
- SysdigThe company that applied the Wireshark mindset to system calls, then built Falco on top.
- SysEx (System Exclusive)MIDI's escape hatch: a message whose contents are entirely up to the manufacturer.
- sysfsThe virtual filesystem under /sys mirroring the kernel's view of the hardware — devices, drivers and their settings.
- syslogThe standard for log messages in the Unix world. Originally written for sendmail in the 1980s, documented after the fact as…
- SysopThe person who ran a dial-up bulletin board — sole administrator, moderator, and often the only user who could get in when…
- Sysop chatThe BBS feature that let a caller summon the sysop and type back and forth with them in real time.
- SystemSturdy context-dependent term. Depending on context: operating system, infrastructure, daemon, distributed architecture, or…
- System call (syscall)Function call from a user-space process into the kernel — to read a file, send a network packet, create a process. The only…
- System promptThe initial instruction an LLM receives that sets its role, tone and rules — before the user starts talking.
- System trayThe row of small icons in the corner of the panel where programs with no window to show still get to be seen: network…
- System VAT&T's commercial Unix branch — one half of the Unix wars, and the ancestor of every init script with runlevels.
- System76The Denver computer maker that sells machines with Linux preinstalled and eventually got tired enough of other people's…
- systemdThe init system on most modern Linux distros — starts and supervises all services.
- systemd timersystemd's cron alternative. Two files per job: foo.timer + foo.service. More powerful than cron (calendar expressions…
- systemd-bootA minimal UEFI boot manager, formerly known as gummiboot and now part of systemd. It does one thing: shows a menu of EFI…
- SystemVerilogThe extension that turned Verilog into both a design and a verification language. In practice two different languages that…
- TCP slow startTCP algorithm that probes the network's capacity at the start of a connection — starts with a small congestion window and…
- Twitter SpacesTwitter's/X's live audio rooms (2021) — a live group conversation where hosts speak and listeners can request to talk…
- WINDOW clause (SQL)SQL syntax for defining named window specifications when the same window frame is used by multiple window functions. WINDOW…
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- 2PCTwo-Phase Commit — classic distributed commit protocol. Phase 1: coordinator sends PREPARE to all participants, all reply…
- 3D RotationThe mathematics of transforming 3D coordinates by rotation matrices, a fundamental operation in realtime graphics and the…
- Apache ThriftCross-language serialisation + RPC framework — Facebook, 2007, donated to the ASF. Schema-based (.thrift files)…
- C++ templatesC++'s generic programming mechanism. Write code parameterized by types: template<typename T> class Vector { T data; ... }…
- Nvidia Tesla (now Datacenter GPUs)Nvidia's datacenter/HPC GPU line — passive cooled, no video output. K80 (2014) → P100 → V100 → A100 → H100 → B200/B100. The…
- pgvector + pgvectorscalePostgres extensions for vector similarity — pgvector (Andrew Kane) added the base in 2021, Timescale's pgvectorscale (2024)…
- t-SNE / UMAPDimensionality reduction: project high-dimensional vectors (embeddings) down to 2D/3D for visualisation.
- T3-stackOpinionated TypeScript full-stack: Next.js + TypeScript + tRPC + Tailwind + Prisma + NextAuth. Coined by Theo (T3.gg) 2022…
- T64A file container that pretends to be a cassette tape but is really a small archive of PRG files — handy for emulators…
- TAA (temporal anti-aliasing)Anti-aliasing that averages each pixel against its position in previous frames, using motion vectors to line them up.
- Table lockLock on entire table instead of individual rows. PostgreSQL has 8 levels (AccessShare, RowShare, RowExclusive…
- TableauThe analytics tool that let finance drag columns onto a canvas and get charts, instead of emailing spreadsheets back and…
- Tabletop exerciseA discussion-based crisis exercise where participants walk through a fictional security scenario ("ransomware has encrypted…
- Tabula rectaA square of 26 alphabets, each shifted one place — the lookup table behind Vigenère and its relatives.
- Tadayoshi KohnoSecurity researcher who showed that voting machines, pacemakers and cars were all computers — with everything that implies.
- Tag componentA component with no data, whose only job is to be present on an entity or not.
- Tagged unionUnion type with explicit "tag" field that indicates which variant. C/C++ union is untagged (raw memory-share…
- TaglineA randomly picked one-liner that the offline reader stuck to the end of every BBS post — often the only part of the message…
- Taher ElgamalDid his doctorate under Hellman, gave his name to a cryptosystem, then led the work on SSL — the protocol that made…
- Tail call optimization (TCO)When a function call is the last thing that happens, the compiler can reuse the existing stack frame instead of pushing a…
- TailscaleMesh VPN on top of WireGuard — every device talks directly to every other, no central tunnel server, no open ports.
- Tailscale DERPDesignated Encrypted Relay for Packets — Tailscale's relay network that forwards encrypted traffic when two nodes can't…
- Tailwind CSSUtility-first CSS framework — instead of semantic classes, combine small atomic classes (flex justify-between p-4) in HTML…
- Taint & tolerationKubernetes mechanism: a taint on a node repels all pods without a matching toleration. Inverted from node affinity (pod…
- Taints and tolerationsA taint on a node repels pods; a toleration on a pod says it can put up with that. The node's way of saying no, as opposed…
- TaitoA Japanese company that imported vodka and jukeboxes before it made Space Invaders.
- Take-Two InteractiveThe New York publisher that owns Rockstar and 2K, and with them some of the most profitable franchises around.
- Tal RabinCryptographer who turned threshold cryptography and secure multiparty computation into things you can build, not merely…
- TalendA French ETL vendor that took on the expensive data-integration giants with a free, open-source edition.
- talk (Unix)The Unix command for one-to-one chat in a split terminal, where the other person's words appeared character by character as…
- talk.*Usenet's debate hierarchy — a fenced-off area for politics, religion and other subjects on which nobody has ever changed…
- talk.originsThe Usenet group for the evolution-versus-creationism debate, which spawned one of the first large fact archives on the net.
- Talkback (studio)The microphone and button that let the engineer in the control room speak straight into the musicians' headphones.
- TalkboxA speaker driver that pipes an instrument's sound through a tube into the player's mouth, where it gets shaped into words.
- TalkerA MUD with the game stripped out and the chatter left in — telnet chat servers that thrived at British universities in the…
- TalkomaticOne of the first multi-person chat rooms, built on the PLATO system fifteen years before IRC.
- Tally stickNotches cut into wood or bone that counted sheep, debts and days long before there were numerals to write down.
- Talos LinuxA Linux built solely to run Kubernetes, with no shell, no SSH and no package manager. Everything is done through an API.
- Tammo HinrichsFarbrausch's musician and audio coder, kb, whose V2 synthesizer solved the 64k intro's sound problem.
- Tamper resistanceTamper resistance is the set of physical and logical measures that make opening a crypto device expensive without the keys…
- TandbergA Norwegian radio maker that became a world leader in videoconferencing and ended up as Cisco's meeting-room division.
- Tandem ComputersComputers built never to stop, which is why so many of them are still humming away in bank basements.
- Tandem-DMA double-block-length compression function in which two Davies–Meyer steps run one after the other, the second fed by the…
- Tandy CorporationA Fort Worth leather business that bought an electronics chain and suddenly had thousands of shops to sell home computers in.
- Tangent spaceThe local coordinate frame on a surface — tangent, bitangent and normal — that normal maps are stored in so they work no…
- TaniumA platform for asking a question of a few hundred thousand computers and getting the answer in seconds rather than days.
- Tanja LangeGerman cryptographer at Eindhoven working on curves, fast implementations and cryptography that survives quantum computers.
- TanStack FormType-safe headless form library. TanStack (Tanner Linsley). React + Vue + Solid + Svelte support. v1 (Oct 2024). Killer…
- TanStack Query (React Query)Server-state library for React/Vue/Svelte/Solid — caching, deduplication, retry, mutations, optimistic updates. "Forget…
- TanStack RouterType-safe React router from Tanner Linsley — fully typed routes with search params, loaders, code splitting. Competitor to…
- TanStack TableHeadless table library — just state logic (sorting, filtering, pagination, grouping), you build the UI. Framework-agnostic…
- Tap codeSimple code that sends letters as knocks on a 5×5 grid, and that prisoners of war in Vietnam used to talk through cell walls.
- TAP formatA file format that stores a cassette-tape signal as pulse lengths rather than finished bytes.
- TAP portTest Access Point — physical inline device that creates passive copy of network traffic. Optical fiber TAP: prism splits…
- Tape autoloaderA single tape drive with a small magazine that swaps cartridges for you — the middle ground between a bare drive and a full…
- Tape libraryAn automated archive where a robotic arm pulls tape cartridges from slots and feeds them to one or more tape drives.
- Tape markA special recorded pattern that marks end-of-file on a tape — the tape's file separator, readable without understanding the…
- Tape saturationThe soft distortion magnetic tape produces when fed more signal than it can take — a technical limitation that became a…
- Tape streamerA tape drive that writes data in one continuous stream instead of starting and stopping for every block.
- Tape tensionThe force that keeps tape taut against the head — too much stretches and deforms it, too little loses contact and with it…
- TapeoutThe moment a chip design is declared finished and sent off for mask manufacturing. The name comes from when it was literally…
- TarantoolAn in-memory database with a Lua interpreter built in — application server and data store in the same process.
- Tascam PortastudioA four-track recorder with a built-in mixer running on ordinary cassettes, which moved multitrack recording from the studio…
- Task arithmetic (task vectors)Treating the difference between a fine-tuned model's weights and the base model's as a vector you can add and subtract…
- Task View (Windows)Windows 10's window overview on Win+Tab, which in 2015 finally gave Windows built-in virtual desktops — twenty-nine years…
- TaskbarThe strip along the screen edge with one button per open window — Windows 95's most copied idea, which Unix desktops adopted…
- Tata Consultancy ServicesTCS: India's oldest and largest IT services company, one branch of a conglomerate that also makes steel, salt and trucks.
- Tatsuaki OkamotoThe NTT researcher behind the MOV attack and the Fujisaki–Okamoto transform, which now sits inside the post-quantum…
- Tatu YlönenFinnish researcher who wrote the first version of SSH after someone sniffed passwords off his university's network.
- TauriRust-based Electron competitor — uses the OS's built-in webview instead of bundling Chromium. ~5 MB bundles instead of 100+.
- Tavis OrmandyThe Google researcher who has found more serious bugs in security products than many security vendors have shipped products.
- TBBS"The Bread Board System" — the commercial BBS that took multiple phone lines on a single computer seriously.
- tc (Linux)Linux traffic control — command + kernel subsystem to shape, prioritize, drop packets. Part of iproute2 package. Powerful…
- Tcl (Tool Command Language)A scripting language by John Ousterhout, Berkeley 1988. Built on a single idea: everything is a string, and every line is a…
- TCP (Transmission Control Protocol)Reliable transport — packets are delivered in order, lost packets are retransmitted.
- TCP BBRBottleneck Bandwidth and Round-trip propagation time — Google 2016. TCP congestion control that models the network's…
- TCP CUBICLinux default congestion control since 2.6.19 (2006). Loss-based: increases cwnd via cubic function, halves on packet loss…
- TCP Fast Open (TFO)TCP extension that lets the client send data directly in the SYN packet — saves 1 RTT on repeat connections. RFC 7413.
- TCP keepaliveTCP option: send an empty probe periodically to verify the remote end is still alive + keep NAT/firewall state warm. Linux…
- TCP pacingSpreading packets evenly across the round-trip time instead of firing them in bursts as soon as the window allows. A…
- TCP RenoClassic TCP congestion control. Reno (1990) built on Tahoe + Fast Recovery (half-cwnd, not set-to-1). AIMD: additive…
- TCP three-way handshakeThe classic SYN → SYN-ACK → ACK sequence that establishes a TCP connection. Ensures both sides are synchronised before data…
- TCP VegasThe first congestion control to measure delay instead of waiting for packet loss. Better in almost every way, and therefore…
- TCP windowThe amount of unacknowledged data a TCP sender may have "in flight". Receiver window (rwnd) governs flow control; congestion…
- TCP-AO (TCP Authentication Option)The successor to TCP's old MD5 signatures, available since 2010 and still barely used. What protects BGP sessions in theory.
- TCP/IPThe fundamental protocol stack the entire internet is built on.
- tcpdumpThe command-line packet sniffer — the thing that actually shows what is on the wire once every other theory has run out.
- TDD (Test-Driven Development)Write the test first (red), then the code to make it pass (green), then refactor.
- TDIFTascam's digital audio interface: eight channels in each direction over a single cable with a 25-pin D-sub connector.
- TDKJapanese electronics firm that commercialised ferrite, became a cassette-tape icon, and now makes the batteries in your…
- TDM (Pro Tools)Digidesign's system of DSP cards and a time-multiplexed bus that let Pro Tools mix and run effects long before host CPUs…
- TDMR (two-dimensional magnetic recording)A technique where several read heads sample neighbouring tracks at once and compute away the interference between them, so…
- TDP (Thermal Design Power)How much heat a CPU/GPU emits under typical load — drives requirements for cooling and PSU.
- TE ConnectivityThe world's largest connector maker, spun out of Tyco with roots in post-war AMP.
- TEAThe Tiny Encryption Algorithm — a 1994 block cipher that fits in a few lines of C, which is exactly why people misuse it.
- Team Fortress 2Valve's class-based team shooter from 2007 that invented the hat economy — cosmetic microtransactions inside a game.
- TeamCityJetBrains' build server — the Jenkins alternative for teams that would rather pay than maintain plugins.
- TeamSpeakVoice chat for gaming, launched in 2001. The idea was simple: low latency, low bandwidth and a server you run yourself. It…
- TeamViewerGerman remote-desktop software that became shorthand for "call IT and let them drive your machine."
- Tear lineThe three dashes, ---, that marked where the human part of a FidoNet post ended and the network's bookkeeping began.
- Tear-off menuA drop-down menu with a dashed "perforation" at the top: click it and the menu comes loose as a small window of its own that…
- TearingThe horizontal seam that appears when the display gets halfway through drawing before the graphics card switches to the next…
- Tech-techThe demo effect where a logo ripples sideways like a flag in the wind, because every scanline is shifted by a different…
- Technical debtThe hidden cost of "quick fixes" — you save time now but pay heavily later when the code becomes hard to change.
- TechnovikingFootage from a Berlin street party in 2000 where a muscular man in cloth wristbands takes possession of a dancing crowd. Six…
- TECO (Text Editor and Corrector)Cryptic text editor from MIT, 1962 (Dan Murphy). Its own Turing-complete "macro" language. Famously single-character — the…
- TED (Commodore)Commodore's combined video and sound chip for the budget Plus/4 and C16 machines.
- Ted Ts'oThe Linux developer who wrote /dev/random and led Kerberos work at MIT — two of the most widely used security building…
- TEE (Trusted Execution Environment)Hardware-isolated computing environment where code + data are protected from even the OS + hypervisor. Examples: Intel SGX…
- Teenage EngineeringThe Stockholm company that makes synths which look like design objects, and design objects for other people which…
- TektonKubernetes-native CI/CD system. CNCF Graduated 2023. Pipeline + Task + PipelineRun as K8s resources. Written in Go. Backend…
- TektronixThe Oregon company that made the oscilloscope every engineer's default instrument, and whose graphics terminals xterm still…
- Tele2The operator Jan Stenbeck built to needle the Swedish state telecom monopoly – and it worked.
- Telebit TrailBlazerThe pricey high-speed modem that, in the late 1980s, carried a large share of Usenet's traffic over ordinary phone lines.
- TELECOM DigestOne of the net's oldest moderated mailing lists, about telephony, mirrored to Usenet as comp.dcom.telecom.
- TelegardA DOS bulletin-board package whose leaked source code became the ancestor of a whole family of other systems.
- TelegramChat app from the Durov brothers (creators of VKontakte), launched in 2013 — cloud-stored history, "channels" up to millions…
- Telegram botTelegram's Bot API from 2015, notoriously easy to get started with: talk to @BotFather, get a token, and one HTTP call is…
- Telegram channelA one-way broadcast in Telegram: admins post, an unlimited number of subscribers read but cannot reply (unless a discussion…
- Telegram Secret ChatTelegram's E2EE mode — opt-in, device-specific (not shown on other logged-in devices). Self-destruct timer, no forwarding…
- TelegraphoneThe Dane who recorded sound onto steel wire in 1898 invented magnetic storage — half a century before anyone thought to…
- TelehouseJapanese-owned data centre company whose Docklands buildings became one of Europe's most important meeting points for…
- TelelogicThe Swedish telecom monopoly's software house in Malmö, selling specification and requirements tools to telecom and defence.
- TelenetAmerica's first commercial packet-switched data network, built by the people behind the ARPANET.
- TelenorNorway's old state telecom, which was corporatised, listed, and then went to Asia to find the customers Norway didn't have…
- TeleportAccess proxy that replaces static SSH keys and database passwords with certificates valid for a few hours, issued after…
- TeletextNews in forty characters per line, smuggled through the invisible lines of an analogue television picture.
- Teletext artPictures drawn in teletext's mosaic graphics — 40 characters wide, eight colours, no exceptions.
- TeletypeThe electromechanical typewriter wired to the computer — still haunting every Unix system through the abbreviation tty.
- TeletypesetterPunched tape that let a typesetting machine run without a typesetter — and let the wire services set the nation's newspapers…
- TeleUSEThe Swedish Motif builder: written in Malmö by Telelogic, a spin-off of the state telecom, with its own dialog language for…
- TelexThe global network of teleprinters, where you "dialled" a subscriber and your text printed out on a paper strip at the far…
- TeliaSweden's former state telecom monopoly, incorporated in 1993 and turned Nordic carrier by its merger with Finland's Sonera.
- TelixA DOS terminal program that was, for a whole generation, the front door to the BBS world: dialling directory, ANSI graphics…
- TellabsThe supplier of the boxes in carrier switch rooms that no subscriber ever laid eyes on.
- TelnetPlaintext remote shell protocol. RFC 854 (1983), from the ARPANET era. Fully replaced by SSH as industry standard since…
- Telnet option negotiationThe small protocol tucked inside Telnet where client and server agree on what they both support, one byte at a time.
- TelnyxA Chicago-based Twilio rival that decided to own the pipes rather than rent them.
- TemperatureParameter controlling how randomly an LLM picks the next token — 0 = deterministic, 1 = creative, 2 = chaos.
- Temperature (LLM)Sampling parameter that controls LLM randomness. T=0 = greedy (always most probable next token, deterministic). T=1 = native…
- Temperature (sampling)A parameter that controls how random an LLM's output is. Low temperature (near 0) makes the model focused and predictable…
- TEMPESTThe NSA codename for the study of compromising emanations — the fact that electronic equipment unintentionally leaks…
- Template attackA two-stage side-channel attack: first profile a copy of the device you control, then a handful of measurements on the…
- Template engineA program that merges a template with data into finished text — usually HTML, but equally email, configuration files or SQL…
- TempoGrafana Labs's distributed tracing backend. Storage directly in object store (S3/GCS) → extremely cheap compared to…
- Tempo mapThe track in a DAW that records tempo and time-signature changes over time, and thereby translates bars and beats into…
- Temporal reprojectionReuses the previous frame's result by reprojecting it into the current one, spreading expensive effects across several…
- Temporary tableSession-scoped table — exists only for the current session/connection, auto-dropped on disconnect. CREATE TEMP TABLE staging…
- TemuPDD Holdings' (China's Pinduoduo) ultra-cheap shopping app for the West — launched September 2022 in the US, fastest app…
- TenableThe company behind the Nessus vulnerability scanner, and the textbook case of a free project closed off once it started…
- TencentStarted with an ICQ clone in Shenzhen and became the world's largest games company along the way.
- Tension armA spring-loaded arm that rides the tape to keep tension steady and soak up speed differences between the reels and the…
- Tensor CoreSpecialized matrix-multiply accelerators in Nvidia GPUs. Volta (V100, 2017) introduced. Tensor cores on H100 deliver 10x…
- Tensor parallelismSplitting individual weight matrices across several GPUs so each card computes part of the same layer. Necessary when a…
- TensorFlowGoogle's ML framework — long dominant, has lost ground to PyTorch.
- TensorRT-LLMNvidia's inference library for language models. It compiles the model into an optimized engine locked to a particular GPU…
- TenstorrentThe Toronto AI-chip company betting on RISC-V and open software rather than imitating Nvidia.
- TeradataThe data warehouse retailers bought to find out what people actually buy, long before anyone said big data.
- TeradyneThe machines that decide whether a chip works before anyone has paid for it.
- Teresa LuntThe researcher who led SRI's IDES project, one of the first intrusion detection systems that actually ran.
- termA Linux and Unix tool that split a single modem line into a shell account into several simultaneous connections, without…
- Terminal (Shell)Text-based interface to the OS — you type commands instead of clicking.
- TerraformThe dominant IaC tool — define AWS/Azure/GCP resources in HCL, apply changes.
- Terraform moduleA reusable, parameterized package of Terraform resources — infrastructure's equivalent of a function. Instead of copying the…
- Terraform stateThe JSON file Terraform uses to know what exists in reality — the mapping between code and resources.
- TerragruntThin wrapper around Terraform — Gruntwork, 2016. Addresses DRY problems: share backend config, provider config and variables…
- Terrain renderingDrawing a landscape with more triangles near the camera and fewer far away, without the switch ever showing.
- TessellationLetting the GPU subdivide coarse surfaces into many small triangles, driven by a factor that usually shrinks with distance.
- Test-time computeThe idea of spending more compute at inference (not training) — let the model think longer, generate more candidate answers…
- Test-time trainingThe model continues to update its weights during inference based on the current input — adapts to each example. Stanford +…
- TesteryThe section at Bletchley Park that broke the Lorenz cipher by hand — the laborious half of the job, and the half no machine…
- TestFlightApple's service for distributing test builds of iOS apps outside the App Store — up to 10,000 external testers.
- TestNGThe Java testing framework that introduced annotations, groups and parallel execution — and forced JUnit to catch up.
- TetragonCilium-suite eBPF runtime-security + observability. Isovalent (acquired by Cisco 2024), 2022. Kernel-level event detection +…
- TetrisWritten on a Soviet research computer in 1984, spread with nobody able to charge for it, and for ten years unclear who…
- TeXKnuth was so unhappy with the typesetting of his own book that he wrote a typesetting system — and kept at it for ten years.
- Texas InstrumentsWhere the integrated circuit was first demonstrated in 1958 — and where the graphing calculator turned into an unexpectedly…
- TexelThe texture-space counterpart to a pixel — one addressable sample in a texture map.
- Texel densityHow many texture texels cover a given area of the world — the measure of how uniformly detailed surfaces appear.
- Text mode demoA demo that may only draw with characters — a grid of perhaps 80×50 cells in 16 colours — and still has to look like…
- Text splitter (chunking strategy)How you slice long documents into chunks for embedding and RAG — arguably the single most important architecture choice in a…
- text-wrap: balanceCSS property that distributes a heading evenly across its lines instead of filling the first one and leaving a single word…
- Text4ShellCVE-2022-42889 — RCE in Apache Commons Text via script interpolation. ${script:javascript:...} triggers Nashorn JS engine +…
- textfiles.comJason Scott's 1998 archive preserving the BBS era's text files — anarchy, phreaking, humour and boast files that would…
- Texture arrayA stack of identically-formatted textures addressed by an index and bound as a single resource — an atlas without the seams.
- Texture atlasMany small images packed into one large texture so the GPU can draw them without switching textures between each.
- Texture bleedingColour from neighbouring pixels leaks across the edge of a tile or sprite when the texture is filtered or mipmapped.
- Texture compressionBlock formats like DXT and ASTC that stay compressed in video memory and are decoded by the hardware on each fetch — unlike…
- Texture filteringHow the GPU picks a colour when a pixel lands between texels — from blocky nearest-neighbour up to anisotropic sampling that…
- Texture mappingPasting an image onto a 3D surface — how a model of a few hundred triangles can look like brick, wood or skin.
- Texture seamThe visible join where two UV islands meet on a texture — colour or light bleeds across the edge and shows up as a line on…
- Texture splattingBlending several tiling textures across terrain using a control map that says how much of each shows at every point.
- Texture streamingLoad only the texture resolutions that are actually visible right now instead of keeping every texture at full resolution in…
- Texture wrappingThe sampler rule for what happens when texture coordinates fall outside the 0–1 range.
- TF-IDFTerm Frequency × Inverse Document Frequency. Classic text-ranking formula: word importance = how often in document × how…
- TFMXChris Hülsbeck's music routine for the Amiga, best known as the sound of Turrican.
- Thai DuongVietnamese security researcher who helped break TLS three years running — BEAST, CRIME and POODLE all carry his name.
- Thales LunaAn HSM line that started in Canada, changed hands three times, and is now Thales's main HSM family — after Thales was made…
- ThawteA South African certificate authority whose sale to VeriSign paid for a trip to space and for Ubuntu.
- THD (total harmonic distortion)How much harmonic content a device adds to a pure tone, expressed as a fraction of the fundamental.
- The 414sThe Milwaukee teenagers who got into Los Alamos and a cancer hospital with default passwords in 1983, and in doing so got…
- The Black ChamberThe nickname of the American cipher bureau Herbert Yardley ran through the 1920s, shut down in 1929.
- The Black LotusOne of the most acclaimed Amiga demo groups, known for putting design and music ahead of sheer effect-count.
- The CodebreakersDavid Kahn's 1967 book is still the one people point to when they ask where the history of cryptography starts.
- The Crypto WarsThe 1990s fight over whether ordinary people were allowed strong encryption — won by the cryptographers, and restarted…
- The GatheringOne of the world's largest computer parties — the Norwegian demoscene's annual Easter gathering in the Vikingskipet skating…
- The Gold-BugEdgar Allan Poe's 1843 story, in which a simple substitution cipher is solved with letter frequencies.
- The GrugqPseudonymous researcher who went from anti-forensics to exploit brokering and then became the scene's most quoted voice on…
- The Hacker CrackdownBruce Sterling's 1992 non-fiction account of the year American law enforcement discovered hackers — and hackers discovered…
- The Hacker ManifestoA short, angry text from 1986 that became hacker culture's creed: "My crime is that of curiosity."
- The Hitchhiker's Guide to the InternetA 1989 RFC that explained the internet to people who had just been given an account and had no idea what to do with it.
- The Internet Adapter (TIA)A program that ran on the provider's Unix box and made an ordinary shell account look like a SLIP connection — the graphical…
- The JugglerEric Graham's ray-traced juggler from 1986 that proved a home computer could do photorealistic 3D.
- The LoungeA self-hosted web client for IRC written in Node.js. It combines client and bouncer in one: the server holds the connection…
- The Major BBSThe BBS package that let a single DOS machine answer dozens of phone lines at once, and with that made real-time chat and…
- The Mod ArchiveOne of the web's largest archives of tracker music in module formats, community-run and free.
- The Open GroupThe consortium that has owned the UNIX trademark since 1996 and decides what may call itself one — and which for a few years…
- The PartyA Danish demoparty that, between 1991 and 2002, was one of the scene's largest annual gatherings — the Christmas meet-up…
- The SilentsScandinavian demogroup that moved from the C64 to the Amiga and was one of the big names around 1990.
- The SourceOne of the first commercial online services for home computer owners, launched in 1979 and shut down by its biggest rival a…
- The Traitorous EightThe eight engineers who left Shockley in 1957 and founded Fairchild — the seed of Silicon Valley.
- The WELLThe dial-up discussion community in Sausalito that became the template for how people described online communities at all.
- The Whole Internet User's Guide & CatalogEd Krol's 1992 book that taught a generation to use telnet, FTP, Gopher and Usenet — written just before the web made most…
- The World (ISP)The first provider to sell dial-up internet access to anyone who wanted it, launched in Brookline outside Boston in 1989.
- TheC64A licensed C64 replica whose familiar case hides an ARM chip running an emulator.
- TheDrawThe DOS era's standard tool for drawing ANSI and ASCII graphics for BBS screens and intros.
- TheDraw fonts (TDF)The file format for TheDraw's text fonts: big letters built from block characters and colour, behind countless BBS logos.
- Theo de RaadtCanadian developer who founded OpenBSD and turned paranoid code auditing into an operating system's entire personality.
- TheoryNetA 1977 email service for theoretical computer scientists — a small trial balloon that proved researchers outside ARPANET…
- ThereminThe instrument you play without touching it: the distance from your hands to two antennas sets pitch and volume.
- Thermal asperityA read-signal spike thrown when a magnetoresistive head grazes a bump — friction heat drowns out the magnetic signal.
- Thermal Design Power (TDP)The amount of heat (in watts) a processor is expected to dissipate under typical load, which the cooling system must be…
- Thermal inkjetThe method that boils the ink to make it fire itself out — one vapour bubble per droplet, tens of thousands of times a…
- Thermal paperPaper coated with a heat-sensitive layer that blackens where a hot printhead touches it — no ink, no cartridge, but the…
- Thermal paste (TIM)Paste between CPU/GPU and cooler that fills microscopic gaps — gives 5-15°C better cooling.
- Thermal printerA non-impact printer that burns the image onto the page with heat instead of striking ink against it.
- Thermal recalibrationWhen a hard drive periodically interrupts itself to re-seek the servo tracks and compensate for the metal having expanded…
- Thermal throttlingCPU/GPU automatically lowers the frequency when temperature approaches Tjmax (typically 95-105 °C). Protection against…
- Thermal transferA printing method where a heated printhead melts wax or resin off a ribbon onto the media.
- Thermal Velocity BoostIntel's opportunistic boost feature that gives the CPU a bit of extra clock frequency as long as it's kept below a certain…
- Thermofax3M's 1950 copying process that burned the copy into being with infrared light — the office's first seconds-fast copier…
- Theta*A variant of A* that lets path segments run at any angle instead of forcing the route onto a grid's eight compass directions.
- Thiele/Small parametersA handful of measurements describing a bass driver electrically and mechanically, so the enclosure can be calculated rather…
- Thin-film headA read/write head whose coil and poles are photolithographed as thin films, the successor to hand-wound ferrite heads from…
- Thinking MachinesThe company behind the Connection Machine, which bet on tens of thousands of simple processors instead of one fast one, and…
- Thomas DecruBelgian cryptographer at KU Leuven who helped break SIKE in 2022 – after eleven years of scrutiny, in about an hour, on one…
- Thomas DrakeThe NSA executive who complained about a failed billion-dollar programme through proper channels and was charged with…
- Thomas DullienGerman reverse engineer, better known as Halvar Flake, who turned binary diffing into a tool and exploitation into a theory.
- Thomas PeyrinFrench cryptographer in Singapore who made SHA-1 collisions cheap enough to impersonate someone's PGP key.
- Thomas PhelippesElizabethan cryptanalyst and forger who read Mary Queen of Scots' letters and helped secure her conviction.
- Thomas PorninFrench cryptographer who wrote the standard for deterministic DSA signatures and the BearSSL TLS library, where every line…
- Thomas PtacekSecurity researcher whose 1998 paper showed network intrusion detection could be fooled by design — and who later taught a…
- Thomas RidPolitical scientist who argued that cyberwar is not coming, and that the real threats are espionage, sabotage and…
- Thomas RistenpartCryptographer who showed that your cloud VM may have a neighbour listening in — and later that plenty of "secure" encryption…
- Thomas RothGerman hardware security researcher, better known as "stacksmashing", who turned voltage glitching of microcontrollers into…
- Thorsten HolzGerman security researcher who helped turn honeypots and botnet measurement into an academic discipline.
- ThoughtSpotAnalytics tool that sells itself as "Google for your data" — you search in a box and get a chart back.
- ThoughtworksChicago-born consultancy with an outsized influence on how the rest of the industry writes and tests code.
- Thread (IoT protocol) (Thread Protocol)IPv6-based mesh radio protocol for IoT — the preferred transport beneath Matter.
- Thread (process)A path of execution inside a process — multiple threads in the same process share memory.
- Thread DirectorIntel's hardware mechanism that helps the operating system's scheduler place the right thread on the right core type (P or…
- Thread replyReplying to a specific message in a side thread instead of the main feed, so a sub-conversation stays together without…
- ThreadiverseA nickname for the Reddit-like part of the Fediverse — link aggregation and threaded discussions in federated communities…
- ThreadripperAMD's prosumer CPU — between Ryzen and EPYC, aimed at 3D rendering, compilation, and AI tinkering.
- Threadripper PROWorkstation version of Threadripper — more PCIe lanes (128), eight-channel RAM, ECC support. Threadripper PRO 7995WX = 96…
- ThreadsMeta's text-based microblog — launched 5 July 2023, tied to your Instagram account. The fastest app launch ever (100 million…
- Threads (Meta)Meta's Twitter alternative, launched July 2023 after the Twitter chaos. Bundled with Instagram (requires an Insta account)…
- Threads ActivityPub bridgeMeta's Threads feature: opt-in ActivityPub support so Threads accounts can be followed from Mastodon instances. Launched…
- Threat GraphCrowdStrike's cloud graph database that ties together trillions of security events from every connected machine and looks…
- Threat huntingThe proactive security practice of looking for attackers who are already inside but have slipped past the automated alerts…
- Threat intelligenceCollected and analyzed knowledge about threats — which attackers exist, their methods (TTPs), ongoing campaigns, and…
- Threat modelStructured work on "who could attack us, how, and what do we do about it".
- Threat modelingStructured analysis of security threats to a system. Done at design phase before code is written. Output: threat list +…
- Threat tableThe list every MMO enemy keeps of how much it hates each player — and which decides who it hits.
- Three.jsThe de-facto standard for 3D graphics in the browser — abstracts away the WebGL details, lets you focus on the scene.
- ThreefishA tweakable block cipher with 256-, 512- or 1024-bit blocks, built without S-boxes for the Skein hash.
- ThreemaSwiss E2EE chat app with no phone-number requirement. Anonymous Threema IDs. One-time purchase (~5 EUR). Launched 2012…
- Threshold (compressor)The level at which a dynamics processor wakes up — below it the signal passes untouched, above it the ratio takes over.
- ThrottlingWhen a CPU/GPU lowers its clock to avoid overheating or drawing too much power.
- ThroughputHow much work actually gets through per unit of time — not how fast any single piece of work completes.
- ThunderboltHigh-speed I/O standard from Intel + Apple. TB3 (40 Gbps) standard since 2015. TB4 (same 40 Gbps but stricter spec) 2020…
- Thunderbolt 5Intel's Thunderbolt 5 (2023) — 80 Gbps symmetric, with "Bandwidth Boost" up to 120 Gbps in one direction for displays. Built…
- TI Silent 700Texas Instruments' 1971 portable terminal that printed silently with heat on thermal paper — the journalist's and field…
- TI-99/4AThe first home computer with a 16-bit processor, and the best-known casualty of the price war.
- TI-LFAFast reroute for segment routing that can protect essentially every destination, regardless of what the network happens to…
- TIBCOThe message bus that got Wall Street trading floors talking to each other, long before anyone said "event-driven".
- TIC-80A made-up games console with 240×136 pixels and 16 colours that has become the demoscene's favourite sandbox for tiny intros…
- Tick groupA named phase of an engine's per-frame update that controls when a piece of code runs relative to physics.
- Tick rateHow many times a second a game server steps its simulation and samples input — 64 or 128 in the endless CS arguments.
- Ticker tapeThe printing telegraph that ticked out stock prices on a paper strip — and gave the confetti parade its name.
- TidalCyclesA pattern language embedded in Haskell, where a line like "bd*2 [sn cp]" becomes a drum loop you rewrite while it plays.
- TiDBMySQL-compatible distributed database from Chinese PingCAP — TiKV storage written in Rust, frontend in Go.
- Tide-predicting machineFourier synthesis in brass: a wire running over a dozen pulleys that turn at the rates of the moon and the sun, and the sum…
- Tier 1 networkAn operator that can reach the entire internet solely through settlement-free peering — without ever paying anyone for…
- TIES-MergingA method for merging several fine-tuned models into one, built on the insight that most of a fine-tuning delta is noise and…
- TietoevryA Nordic IT operations giant that runs systems for agencies, municipalities and banks, and is noticed mainly when it breaks.
- Tiger (hash function)A 1995 hash function with 192-bit output, designed for the then-new 64-bit processors.
- TigerBeetleSpecialised financial database — only double-entry bookkeeping, two fixed record types (accounts, transfers), targeting one…
- TikTokByteDance's short-video app — the international version of China's Douyin, launched globally in 2018 after the Musical.ly…
- TikTok DuetTikTok feature: record your own video side-by-side with someone else's. Reactions, harmonies, parodies. Drives a lot of the…
- TikTok ShopIn-app e-commerce inside TikTok — live shopping streams + product tags in videos. Huge in Asia, launched in the US in 2023…
- tiktokenOpenAI's BPE tokenizer, written in Rust with Python bindings. The tool you reach for to find out what a call will cost…
- Tile attribute (attribute table)The extra bytes that say which colour palette each background cell is drawn with — colour stored apart from shape to save…
- Tile collisionCollision resolved against a grid of tiles flagged solid or empty, rather than against arbitrary colliders.
- Tile flippingStoring a flip flag per cell in a tilemap so a single tile can be drawn mirrored horizontally, vertically or diagonally…
- Tile-based renderingA GPU architecture that splits the image into small tiles and renders one tile at a time in fast on-chip memory — built to…
- TiledA free, engine-agnostic editor for grid-based 2D levels, and the closest thing the industry has to a tilemap standard.
- TilemapA game level built as a grid of reused small images instead of one large bitmap.
- TileraMany-core pioneer whose chips packed dozens of identical cores into a grid back in the 2000s.
- TilesetThe palette of individual tile images a tilemap indexes into — the pictures, as opposed to the grid of indices.
- Tiling window managerA window manager that lays windows out side by side with no overlap and leaves the rest to the keyboard.
- TiltDev environment orchestrator for Kubernetes + Docker Compose. Launched 2018 by Windmill Engineering. Smart hot reload…
- Tim Berners-LeeWrote a proposal at CERN in 1989 that his manager annotated "vague but exciting" — and thereby built the web.
- Tim DierksEditor of TLS 1.0 — and the person who later explained that SSL got renamed largely so nobody could say the IETF had…
- Tim FollinBritish game composer who made the ZX Spectrum's beeper sound polyphonic and later pushed NES audio into prog rock.
- Tim HudsonThe other half of SSLeay — the Australian who wrote much of the code around Eric Young's crypto, then spent decades on…
- Tim MayIntel physicist who retired in his thirties and spent the rest of his life predicting what strong cryptography would do to…
- Tim NewshamCo-author of the 1998 paper showing that an intrusion detection system can be shown a different reality from the one the…
- Time of impact (TOI)The fraction of a timestep at which two moving bodies first touch — the number continuous collision detection exists to find.
- Time ProtocolPort 37: replies with the number of seconds since 1 January 1900, packed into 32 bits — and therefore with a built-in expiry…
- Time scaleA global multiplier on the game's simulation clock — set it to 0.5 for slow motion, 0 to pause, 2 to fast-forward.
- Time to collision (TTC)An estimate of how many seconds remain until two moving objects would meet if they held course — the basis for predictive…
- Time-sharingThe idea of letting many users share one computer at once — and thereby the invention of sitting in front of a computer.
- Time-stretchingChanging how long a sound lasts without dragging its pitch along — the trick a tape machine at the wrong speed could never…
- Time–memory trade-offA cryptanalytic method that trades precomputed storage for faster searches for keys or passwords.
- TimeroastingAsking a domain controller for a time reply signed with a computer account's password hash, without being logged in at all…
- TimescaleDBPostgres extension that adds time-series superpowers — automatically partitioned "hypertables", continuous aggregates…
- Timestamps (X11)The X server's own clock: 32 bits of milliseconds riding along on every key press and mouse click, and the thing that…
- TimewarpA reprojection trick that rotates the finished image to the head orientation sampled at the last moment before scanout…
- TiMidityA 1995 software synthesizer that turned MIDI files into audio on machines whose sound cards couldn't do it themselves.
- Timing attackFigure out secrets by measuring how long operations take.
- tin (newsreader)The menu-driven terminal newsreader that put threads on screen instead of leaving them in the reader's head.
- TinderThe dating app that popularised "swipe right" — fundamentally changed modern dating from 2012 onward.
- TinTin++The terminal MUD client that is still maintained, more than thirty years after it started as a hobby project.
- TinybirdManaged ClickHouse-as-a-service with an API layer on top — "define a SQL query, get a real-time endpoint". Madrid startup.
- TinyFugueThe Unix MUD client that turned telnet into a programmable tool, with triggers, macros and several worlds open at once.
- TinyMCEClassic WYSIWYG rich-text editor. Moxiecode (then Ephox, now Tiny Technologies), 2003. Powered WordPress Visual Editor for…
- TinyMUCKThe TinyMUD offshoot that let players program the world in a Forth dialect of its own.
- TinyMUDThe MUD that dropped the monsters and the points: a text world where players talked to each other and built the rooms…
- TinyWMA window manager in about fifty lines of C, written in 2005 to show that everything needed to move, resize and raise windows…
- Tip jarA feature for sending a one-time donation ("tip") to a creator as thanks — Twitch's Bits, YouTube's Super Chat, Twitter's…
- TiptapHeadless rich-text editor built on ProseMirror. The most common 2024 choice for Notion-like WYSIWYG editors. Open source…
- Title barThe strip across the top of a window with the name in the middle and the buttons in the corners, which you drag to move and…
- TiVoThe American recording box that taught viewers to skip adverts and taught Richard Stallman a new word.
- TizenA Linux-based operating system from Samsung and Intel that was meant to be a mobile platform but ended up in TVs and watches…
- TkThe toolkit that let anyone put up an X window with buttons in ten lines of script, at a time when the alternative was a…
- TLA+Leslie Lamport's formal specification language for concurrent systems — describe what the system should do, the model…
- TLBTranslation Lookaside Buffer — CPU cache for virtual-to-physical address translations. Walking the page table is expensive…
- TLC (Triple-Level Cell)NAND flash that stores three bits per cell by distinguishing eight different voltage levels. The standard in practically…
- TLD (Top-Level Domain)The highest level of a domain — .com, .se, .org, .dev.
- tldrawInfinite canvas whiteboard app + SDK. Open source. Famous 2023 "tldraw makes real" demo: draw a UI → get a working webpage…
- TLS (Transport Layer Security)Crypto protocol providing confidentiality + integrity + authentication on TCP. HTTPS, IMAPS, SMTPS, gRPC and many more all…
- TLS 1.3The latest TLS version (2018) — faster handshake, safer defaults, end of old insecure ciphers.
- TLS PRFThe pseudorandom function TLS 1.0–1.2 used to derive the master secret and session keys, until HKDF took over in TLS 1.3.
- TMR headThe read head in practically every modern hard drive: a magnetic tunnel junction whose resistance shifts with the field…
- tmuxTerminal multiplexer. Nicholas Marriott, 2007. Successor to GNU Screen (less buggy, more modern config). Sessions survive…
- TN panel (Twisted Nematic)The oldest and cheapest LCD technology — fast pixel response, but the worst viewing angles and colour.
- TN3270Telnet for IBM mainframes, which didn't talk line by line but in whole screens.
- TNT (The NeWS Toolkit)Sun's object-oriented toolkit for NeWS, written in PostScript and wearing the OPEN LOOK look: the closest NeWS ever came to…
- TOASTPostgreSQL's mechanism for values too large to fit on a page. The name stands for The Oversized-Attribute Storage Technique…
- Tobias EngelGerman security researcher who showed that the mobile network's internal signalling lets anyone with access locate, and…
- TobiiThe Stockholm company that taught computers to see where you're looking — first for people who can't use their hands, later…
- TOCTOUTime-of-Check to Time-of-Use — a race condition where an attacker changes something between the program's check and the…
- TodoistThe to-do app for people who take their lists seriously — type "report every Friday at 5pm" in plain text and it understands…
- TOFUTrust On First Use — security model where the first connection is blindly accepted + saved; future connections verify…
- TOG-CUPThe Open Group's X11 extension for sharing the default colormap with colours somebody else had already claimed.
- Together AIA cloud platform for open generative models — inference, fine-tuning and training, built on the thesis that open weights win.
- Toil reductionThe SRE concept of "toil" is manual, repetitive, automatable work that adds no lasting value and grows linearly with the…
- TOIletFIGlet-compatible program for big text banners in the terminal, with colour and filters on top.
- TokenThe smallest unit an LLM handles — roughly a word, syllable or character.
- Token bindingCryptographically tying a session token (or cookie) to the specific device it was issued on, so that a stolen token is…
- Token bucketRate-limiting algorithm: a "bucket" is filled with tokens at a fixed rate; each request consumes a token.
- Token costThe LLM pricing unit: 1 token ≈ 0.75 English words ≈ 4 bytes. Swedish costs more (token/word ratio ~1.5 vs English 0.75)…
- TokenizerThe component that splits text into tokens before an LLM sees it.
- Tokyo Demo FestJapan's demoparty, running since 2010 to give a small domestic scene the kind of meeting place Europe has had for decades.
- Tokyo ElectronTEL: Japan's largest maker of chip-fab tools, and the one that coats the wafer with photoresist before ASML's machine gets…
- Tom JenningsAmerican programmer who wrote the Fido BBS software and, by extension, started FidoNet.
- Tom KilburnWrote and ran the world's first stored program in 1948, then spent twenty years building machines everyone else copied.
- Tom TruscottThe Duke grad student who, with Jim Ellis, invented Usenet in 1979 because it was cheaper than getting onto the ARPANET.
- Tombstone (database)A marker indicating that a key has been deleted, instead of physically removing the data right away. Necessary in…
- TOML"Tom's Obvious Minimal Language" — Tom Preston-Werner (co-founder of GitHub), 2013. Configuration format with a clearly…
- Tommy FlowersThe telephone engineer who knew that vacuum tubes last if you leave them switched on, and built the world's first…
- TomTomThe Amsterdam company that put a satnav on every other windscreen and then watched the smartphone give it away for free.
- Tone mappingSqueezing a light value with an enormous range down into the narrow band a display can show, without clipping highlights…
- Tone.jsA JavaScript framework that puts musical concepts — bars, notes, synths — on top of the browser's Web Audio API.
- TonerThe fine plastic powder that laser printers and copiers fuse onto the paper instead of liquid ink.
- TongfangChinese ODM, tied to Tsinghua University, behind a large share of the world's cheaper laptops.
- Tool useThe broader ability of an LLM to use external tools — search, code execution, a calculator, databases, APIs — to do things…
- Toolchest (IRIX)The little menu bar in the top-left corner of every SGI screen: 4Dwm's launcher and system menu, driven by a text file and…
- ToolformerMeta paper (Feb 2023) that showed an LLM can self-supervised learn to call external tools (calculator, search API…
- ToolTalkSun's message bus for desktop applications, letting them hand jobs to one another — and better remembered for its security…
- Top-k samplingA sampling method where, at each step, the model may only choose among the k most likely tokens (e.g. the top 40), and the…
- Top-level awaitThe ability to use await directly at the top level of an ES module, without having to wrap it in an async function. The…
- Top-p (Nucleus sampling)LLM parameter: only pick the next token from those that together make up p% of the probability.
- Top-p sampling"Nucleus sampling" (Holtzman et al. 2019) — at each step you sample only from the smallest set of tokens whose cumulative…
- Top-postingWriting your reply above the entire quoted message — standard practice in corporate email, a mortal sin on Usenet.
- TopazAmigaOS's default bitmap font — the blocky system typeface that became the demoscene's visual signature.
- Topological qubitMicrosoft's long game — qubits where information is stored in the system's shape rather than in individual particles, and so…
- Topological sortLinear ordering of a DAG's nodes such that for every edge u→v, u comes before v. "Dependencies first".
- Topology spread constraintA Kubernetes mechanism for distributing pods evenly across topology domains (nodes, zones, regions). More modern and…
- TOPS-10The PDP-10 operating system where a large part of hacker culture and the early network protocols actually came into being.
- TOPS-20DEC's operating system for the DECSYSTEM-20 — home to much of ARPANET-era hacker culture, killed off with its own hardware.
- TopsiteThe invite-only FTP server at the top of the warez pyramid, where releases land first and fastest.
- TopViewIBM's text-mode windowing environment for DOS, which ran several programs at once — and sold poorly.
- Tor (The Onion Router)Anonymity network — your traffic bounces through three volunteer nodes, each only knowing the next hop.
- Torben PedersenDanish cryptographer whose 1991 commitment scheme now hides amounts in cryptocurrencies that didn't exist when he wrote it.
- Torn-tape relayMessage relaying in which an operator literally tore the paper tape off a reperforator and fed it into the next line's…
- Torpedo Data ComputerAn electromechanical calculator in the submarine's conning tower that solved the firing problem continuously — and proved…
- Torque (game engine)The Tribes 2 engine, resold by former Dynamix developers for 100 dollars — one of the first game engines indie developers…
- Torque amplifierA friction wheel gives the right rotation but almost no force — the torque amplifier let a nearly powerless turn command a…
- TOSECA cataloguing project that tries to name and checksum every file that ever circulated for old computers and consoles.
- ToshibaThe Japanese conglomerate that invented flash memory, sold it off, and watched it become worth more than everything it kept.
- TOSLINKToshiba's optical connector for digital audio — a plastic fibre carrying red light, with S/PDIF at home and ADAT in the…
- TosserThe program in a FidoNet node that unpacks incoming mail packets and sorts echomail into the right conference in the BBS's…
- TOTPTime-based One-Time Password (RFC 6238) — a 6-digit code generated from a shared secret plus the current time (30-second…
- ToxiproxyTCP proxy from Shopify that lets you inject network faults (latency, packet loss, bandwidth limit, connection drop) into…
- TP-LinkChinese manufacturer that ships more Wi-Fi routers than anyone, mostly by being the cheapest option that works well enough.
- TPM (Trusted Platform Module)Dedicated security chip on the motherboard — stores encryption keys, does hardware-backed authentication.
- TPU (Tensor Processing Unit)Google's ASIC chip designed for neural networks — faster and more power-efficient than GPUs on the right workloads.
- TPU (hardware)Tensor Processing Unit — Google's custom-built chip (ASIC) for machine learning, optimized for the massive matrix…
- TR-31A key block format that binds a symmetric key's usage, algorithm and mode to the key material itself.
- TR-34The ANSI X9 standard for distributing symmetric keys to payment terminals and ATMs using asymmetric cryptography instead of…
- TraceeRuntime security + forensics tool. Aqua Security 2020. eBPF-based syscall + kernel-event tracing. Standalone CLI or daemon…
- TracerouteA tool that shows every router hop a packet takes on the way to its destination.
- Track density (TPI)How tightly tracks are packed radially, measured in tracks per inch (TPI) — one of the two axes that together give areal…
- Track freezeA DAW feature that temporarily renders a track and its plugins to audio to free up the CPU.
- trackdisk.deviceThe Amiga's built-in floppy driver, which read a whole track at a time and decoded MFM in software.
- Tracker (BeOS)The BeOS file manager and desktop of the 1990s, built in Finder's spatial tradition but with database queries as folders…
- Tracker musicMusic software where the song is written as a grid of notes scrolling from top to bottom, with samples instead of synth…
- TrackmoThe demoscene's seamless long form: a demo that streams straight off the disk's tracks while the effects roll.
- Tractor feedA paper transport where toothed wheels grip rows of holes along the edge of continuous stationery.
- TracyAn open-source profiler for real-time software that shows what every thread did in every frame, down to the nanosecond.
- Trader (warez)The scene member who races to move fresh releases between topsites — the FTP era's answer to the old courier.
- TradeWars 2002The space-trading game that became one of the most-played door games on dial-up BBSes.
- TraefikCloud-native reverse proxy and ingress controller — Emile Vauge, 2015 (Containous, now Traefik Labs). Automatic config via…
- Traffic shapingSmoothing traffic by buffering and delaying packets so the flow stays under a target rate — "shaping". Gentler than a…
- Trail rendererA component that stretches a ribbon of geometry behind a moving object — sword swings, projectile arcs and light trails.
- Trainer (games)A modification that adds cheats to a game — infinite lives, invulnerability, level select — often baked in by whoever…
- TrainingTeaching a neural network via gradient descent — example data + loss function + backprop. Multiple phases in modern LLMs.
- TraitRust's term for "interface" — describes which methods a type implements.
- Trait (Rust)Rust's mechanism for shared behavior. Similar to interfaces (Java) or typeclasses (Haskell). trait Animal { fn speak(&self)…
- Trait objectRust feature: dynamic dispatch via virtual table. Box<dyn Trait> or &dyn Trait. Runtime polymorphism instead of compile-time…
- Trait objectsRust's way of doing dynamic dispatch: dyn Trait hides the concrete type and looks the method up in a vtable at runtime.
- Trammell HudsonThe hardware hacker who showed that a Thunderbolt adapter could overwrite a Mac's firmware, then built firmware you can…
- TrampolinePattern to simulate tail-call optimization in languages without native TCO. Recursive function returns function ("thunk")…
- TransactionA group of database operations treated as a single unit — either all succeed or all are rolled back.
- TranscendA Taiwanese memory maker whose JetFlash sticks and memory modules became everyday purchases.
- TranscodingDecoding material and re-encoding it to another format or bitrate — expensive, and always with some loss.
- Transfer learningUse knowledge from an already-trained model as the starting point for a new task — rather than train from scratch.
- Transform gizmoThe coloured arrows, rings and cubes in an editor that let you move, rotate and scale an object with the mouse.
- TransformerA neural-network architecture from 2017 that drives every modern LLM. Built on the attention mechanism.
- Transformer architectureNeural architecture that replaced RNNs and CNNs for sequence modeling. Vaswani et al., "Attention Is All You Need", Google…
- Transient shaperA dynamics processor that boosts or tames the attack and the tail of a sound, regardless of how loudly it was played.
- TransistorThe fundamental building block of every modern chip — works like a switch controlled by another voltage.
- Transit Gateway (TGW)AWS service that acts as a network hub — connect dozens of VPCs, on-prem networks (via Direct Connect/VPN) and accounts to a…
- Transit vs peeringThe two ways a network connects to the rest of the internet. Transit: you pay an operator to reach ALL of the internet…
- Transition noiseIn modern media the noise comes not from the electronics but from the ragged edge at every bit transition.
- Translation table (Xt)Xt's text format for binding keys and mouse buttons to named actions in a widget, replaceable from ~/.Xresources without…
- TransmetaA Californian chip company that translated x86 code into VLIW in software and promised laptops that would last a full day on…
- TransmonThe superconducting qubit design that became the industry standard — insensitive to charge noise, and therefore long-lived…
- Transpiler"Source-to-source compiler" — translates between two high-level languages. TypeScript → JavaScript, Sass → CSS, CoffeeScript…
- Transposition cipherKeeps every letter but shuffles their order. The opposite of substitution, and half the recipe of every modern block cipher.
- Transposition tableA cache of already-analysed game positions, so a search doesn't recompute the same position just because it arrived by a…
- TransvoxelAn extension of marching cubes that stitches voxel terrain at different detail levels together without cracks at the borders.
- Trapped ionQubits made from individual ions held suspended in electromagnetic fields and controlled with lasers — slower than…
- Trash (Recycle Bin)A folder dressed up as a bin that makes deletion reversible — the part of the desktop metaphor that turned out to be a…
- TrautoniumA German electronic instrument from 1930, played by pressing a wire against a metal rail, that gave Hitchcock's birds their…
- Travan3M's attempt to scale the old QIC cartridge up to the gigabyte class for 1990s desktop and small-server backup.
- Travis CIEarly SaaS CI platform — dominated GitHub open-source from 2012–2018 with YAML-configured .travis.yml. Lost essentially…
- Travis GoodspeedHardware hacker and neighbourly philosopher, best known for the GoodFET, the Facedancer and the journal PoC||GTFO.
- TreeHierarchical data structure — a root, nodes with children, no cycles.
- Tree of ThoughtsA generalisation of chain-of-thought where the LLM explores multiple reasoning branches in parallel, evaluates them, and…
- Tree shakingBundler optimization: remove code that isn't used from the final bundle. Term from Rollup (Rich Harris, 2015). Requires…
- Tree-sitterA parser generator and parsing library built for editors. Written by Max Brunsfeld at GitHub and published in 2018. It…
- TrellixSecurity vendor formed in 2022 when private-equity firm STG merged McAfee Enterprise with FireEye's product business.
- TremoloThe effect that rhythmically raises and lowers volume, driven by a slow oscillator.
- Trend MicroAntivirus company with Taiwanese roots, a Los Angeles start and a Tokyo headquarters – unusual in an industry otherwise…
- Trevor PearceyThe architect of CSIRAC, Australia's first computer and one of the world's five earliest stored-program machines.
- Trevor PerrinThe quiet co-designer of the Signal Protocol and sole author of the Noise framework that WireGuard is built on.
- TrezorThe first commercial hardware wallet for bitcoin — a small device whose only job is to never let your private key out.
- TriadSwedish C64 group founded in 1986 that has drifted between the cracking and demo scenes for nearly forty years.
- Triangle stripA primitive where each vertex after the first two forms a triangle with the previous two, so N triangles cost N+2 vertices…
- TRICKLEA file server for BITNET and EARN that let users without FTP fetch software from the internet's big archives — a drop at a…
- Trie (Prefix tree)Tree data structure where each node represents a character — making prefix search O(prefix-length).
- Trifid cipherThe bifid cipher's three-dimensional sibling: every letter becomes three coordinates in a 3×3×3 cube.
- Trigger (database)Code that runs automatically on INSERT/UPDATE/DELETE of a table — "BEFORE" or "AFTER".
- Trigger (DB)DB procedure that runs automatically on INSERT/UPDATE/DELETE. BEFORE/AFTER + ROW/STATEMENT level. Use: audit logs (who…
- Trigger volumeA collider that only reports overlaps and fires events, without stopping anything that passes through it.
- Trigram (pg_trgm)A method for comparing strings by splitting them into every group of three consecutive characters and counting how many…
- Trilinear filteringBilinear filtering plus a blend between two mipmap levels, hiding the seam where the levels switch.
- Trilogy SystemsGene Amdahl's bid to etch an entire mainframe onto a single silicon wafer — and one of history's most expensive technical…
- TRIMSSD command where the operating system tells the controller which blocks are no longer used by the filesystem. The SSD…
- Trim sheetA single texture holding strips of reusable detail — moldings, panels, pipes, bolts — that many 3D models map onto instead…
- Trinity (TDE)The fork that keeps KDE 3.5 alive for people who never wanted to move to Plasma.
- TrinoDistributed SQL query engine that reads data where it lives — S3, HDFS, Postgres, Kafka, Elasticsearch — without importing…
- TriodeThe tube that could amplify: a third electrode letting a weak voltage steer a large current, which is what made electronics…
- TripadvisorThe world's biggest review site for hotels and restaurants — 1 billion reviews. The "owl" as the ranking icon.
- Triplanar mappingTexturing a surface without UV coordinates by projecting the texture along the three world axes and blending the projections…
- Triple bufferingThree image buffers instead of two, so the GPU can start the next frame without waiting for the display's blanking interval.
- Triple DESThree DES operations in a row, for when the original key has become too short but you still don't want to switch ciphers.
- TripodThe dorm-room free homepage service that became GeoCities' closest rival and Lycos's biggest purchase.
- TriTealThe company that sold CDE in the 1990s to Linux and other platforms the Unix vendors ignored, under the name TED, and…
- Triton (OpenAI Triton)Python DSL for writing CUDA kernels — Tillet at OpenAI. Powers FlashAttention, PyTorch 2's torch.compile, and most modern…
- TriviumA minimalist hardware-oriented stream cipher from eSTREAM, with an 80-bit key and an internal state of 288 bits.
- TrivyVersatile open-source security scanner — Aqua Security, 2019. Scans container images, filesystems, git repos, K8s clusters…
- trnThe threaded successor to rn, which let you follow a Usenet discussion as a conversation rather than a pile of loose letters.
- TrojanMalicious code disguised as something useful — "free Photoshop licence" that's actually malware.
- Trojan Room coffee potA coffee pot in Cambridge that was put on camera to save people pointless walks, and became the world's first webcam.
- Troll (internet)Someone who posts to provoke a reaction rather than to discuss anything.
- TrolltechThe Norwegian company that wrote Qt, sold it under a dual licence, and showed that open source and paying customers can…
- Troy HuntThe Australian who built Have I Been Pwned, where the world checks whether its email address has leaked.
- tRPCType-safe RPC stack for TypeScript monorepos — backend types are inferred directly on the frontend with no codegen or schema…
- TRS connectorThe cylindrical plug with a tip, a ring and a sleeve — inherited from 19th-century telephone switchboards and still…
- TRS-80The one of 1977's three home computers you could actually buy in a shop near you — three thousand shops, to be precise.
- TRSITristar and Red Sector Inc — two Amiga groups that merged in 1990 and became one of the scene's longest-lived brands.
- Tru64 UNIXDEC's 64-bit UNIX for Alpha, renamed twice while the company that owned it was bought out from under it.
- True bypassAn effects pedal that, when switched off, wires its input straight to its output with a mechanical switch, so the circuit…
- True peakThe peak a signal actually reaches between samples, not just the one written in the file.
- TruecallerA Swedish app that tells you who's calling before you pick up — using a phone book built out of its users' own address books.
- TrueNASA network storage operating system built around ZFS, developed by iXsystems. It was called FreeNAS from 2005 and was renamed…
- Trumpet (newsreader)A DOS and Windows newsreader from Tasmania, best remembered for leading to Trumpet Winsock — the program that connected…
- Truncated differentialA differential that fixes only some bits or bytes of the block and leaves the rest free.
- Trusted TypesMakes it a type error to hand a plain string to innerHTML — and thereby removes DOM-based XSS structurally.
- Tseng LabsThe graphics chips enthusiasts checked for on the back of the box around 1990, before 3D made them obsolete.
- TSMCManufactures the chips for almost everyone who designs them — and has thereby become one of the world economy's most…
- TSO/GSO (Segmentation offload)Letting the network card split a large data buffer into correctly sized packets, instead of the processor building each…
- Tsutomu MatsumotoJapanese cryptographer who founded multivariate cryptography in 1988 – and in 2002 fooled fingerprint readers with gelatin.
- Tsutomu ShimomuraThe physicist and security expert whose machines were broken into on Christmas Day 1994 — and who took it personally enough…
- TSV (through-silicon via)A copper conductor running straight through the silicon instead of out to the edge. The basis of all vertical chip stacking…
- TTFB (Time to First Byte)The time from the browser sending a request until the first byte of the response comes back.
- TTFT (Time To First Token)The time from sending a request to the first character appearing. The metric that determines whether a chat application…
- TTL (Time To Live)How long a record should be cached before being fetched fresh — most commonly in DNS.
- TTL (IP)Time To Live — 8-bit field in the IP header (IPv6 calls it "Hop Limit") that's decremented at every router hop. Reaches 0 →…
- TTP (Tactics, Techniques, Procedures)How an attacker operates — strategically (tactic), methodically (technique), concretely (procedure).
- TucowsA download site with two cows in its logo that became one of the world's largest domain wholesalers.
- TumblrMicroblogging platform that became home to fandoms, gif culture, and teen aesthetic — 2010s internet culture in concentrated…
- Tumblr reblogTumblr's sharing mechanism: reblog a post and add your own text/comment to a growing chain. Unlike a retweet, the entire…
- TUN/TAPVirtual network interfaces where the other end is not a cable but a program. The kernel hands packets to a file descriptor…
- Tunnel effectThe endless textured tube you fly through — one of the demoscene's most copied effects, built on two precomputed tables.
- TunnelingEncapsulating one network protocol inside another — VPN over internet, IPv6 over IPv4.
- TupleOrdered collection of values with fixed length and types — (name: string, age: int).
- Turbo (Turborepo)Monorepo build orchestrator — caches task outputs locally and remotely. Vercel acquired Turborepo 2021, full Rust rewrite…
- Turbo Assembler (C64)The assembler the C64 scene wrote its demos in, on the machine itself, long before cross-assembling on a PC became the norm.
- Turbo Boost (PBO on AMD)A CPU clocks above its base frequency when thermal and power budgets allow — briefly "all cores", longer on one or two cores.
- Turbo TapeFast-loading routines that made the Commodore 64's cassette tapes bearable — several times quicker than stock.
- TurbofishRust's syntax ::<T> for explicitly specifying generic types. The nickname comes from looking like a fish (::<>). Named by…
- TurboGopherThe Macintosh client from Gopher's own creators in Minnesota — for many people their first taste of an internet you could…
- TurbolinuxThe Linux company that, in the late nineties, was as big in Japan and China as Red Hat was in the US.
- TurbopackVercel's Rust-based successor to webpack — Tobias Koppers (the webpack creator, employed by Vercel), 2022. Incremental…
- TurborepoMonorepo build orchestrator for JavaScript/TypeScript — Jared Palmer, 2021. Acquired by Vercel in December 2021.
- Turing machineA mathematical toy with an endless paper tape and a read head, invented in 1936 to prove what computers cannot do.
- Turing testTest for machine intelligence. Alan Turing, 1950 paper "Computing Machinery and Intelligence". Original name: "the imitation…
- TuringeryTuring's hand method for working out how the Lorenz machine's wheels were set with cams — built on guesses barely better…
- TURN (Traversal Using Relays around NAT)A relay server that forwards traffic between two peers that cannot reach each other directly.
- TursoEdge-distributed SQLite — built on libSQL (a SQLite fork) and lets you replicate read replicas to hundreds of locations…
- TutaEncrypted email from Hanover that skipped PGP and can therefore encrypt more, but only when the other side uses Tuta too.
- tvtwmTom's Virtual twm — twm with a desktop larger than the screen and a little map to pan around it.
- TWAINThe 1992 standard that let any program pull an image from any scanner.
- Tweakable cipherA block cipher that takes an extra public parameter, a tweak, so the same plaintext gives different ciphertext depending on…
- TweeningGenerating the in-between frames between two keyframes automatically, so an animation needs only a start and an end state.
- TweetcartA complete PICO-8 program short enough to post in a single tweet, source code and all.
- Twelve-Factor App12 principles for cloud-native applications. Adam Wiggins (Heroku co-founder), 2011. Bible for modern web app design…
- Twiggy (Apple)Apple's in-house 5.25-inch floppy drive for the Lisa — technically ambitious, notoriously unreliable, and swapped for Sony's…
- TwilioThe company that wrapped the phone network in a REST API, turning a text message into an HTTP request.
- Twilio FlexTwilio's programmable cloud contact centre from 2018, built on top of the company's voice and SMS APIs.
- Twilio SegmentA customer data platform that collects user events once and forwards them to every analytics and marketing tool, instead of…
- TwiMLTwilio's XML dialect that tells the platform what should happen during a phone call or text message.
- TwineA tool for branching text stories in which every passage is a box on a map and the links between them are the game.
- TwingateZero-trust network access (ZTNA) that replaces the corporate VPN with per-resource permissions instead of per-network ones.
- TwinViewNvidia's own way of driving two monitors from one card as a single X screen: a proprietary alternative to Xinerama that…
- Twist boneA helper bone that distributes a limb's twisting rotation along its length, stopping the "candy-wrapper" collapse that…
- TwistedPython's event-driven networking framework, which had asynchronous I/O a decade before the language itself did.
- Twister effectA classic demo effect: a vertical stack of horizontal bars twisted around its own axis so it looks like a spinning ribbon.
- TwitchLive-streaming platform with a gaming focus — started as a Justin.tv spin-off in 2011, acquired by Amazon in 2014 for USD…
- Twitch BitsTwitch's own microcurrency for "cheering" a streamer. Users buy Bits ($1.40 for 100 bits), spend 1+ in chat to post an…
- Twitch chatThe chat stream alongside a Twitch broadcast — and a cultural form in its own right. Technically it still runs on the IRC…
- Twitch clipTwitch feature: 5-60 second snippet from a live stream that anyone in chat can create. Auto-named with stream title + random…
- Twitter / XMicroblog started in 2006 by Jack Dorsey, Biz Stone, Evan Williams, Noah Glass — originally 140 characters SMS-inspired…
- Twitter bookmarkSave tweet privately without Liking (Like is public). Launched 2018. Premium feature: bookmark folders (2022). The "quiet"…
- Twitter CircleTwitter feature 2022-2023: tweet only to a chosen group of max 150 followers. Clipped "close friends" concept from…
- Twitter listTwitter feature: a curated list of accounts, gives a separate timeline with only those accounts chronologically. Workaround…
- Twitter pollTwitter feature launched 2015: 2-4 options, 1-7 day duration, anonymous votes. Quick feedback mechanism. Also infamous for…
- Twitter threadSeries of numbered tweets (1/, 2/, 3/...) that together form a long essay. Workaround for Twitter's 280-char limit. Format…
- twmThe window manager that shipped as X11's default, and so the first graphical desktop many Unix users ever laid eyes on.
- Two-bone IKThe exact, closed-form IK solution for a chain of exactly two bones — the arms-and-legs case, and by far the most common in…
- Two-out-of-five codeA decimal code where each digit is five bits with exactly two ones — break the pattern and the machine knows something went…
- Two-phase commit (2PC)Protocol for transactions across multiple databases — phase 1: everyone "prepare", phase 2: everyone "commit" or everyone…
- Two-phase lockingClassic concurrency control algorithm: the transaction locks objects it touches, releases all locks only at commit. "Two…
- Two-square cipherEncrypts letter pairs using two keyed 5×5 squares rather than the four-square cipher's four.
- Two-time padReusing a one-time pad key cancels the key out of the equation and leaves the XOR of the two plaintexts behind.
- TwofishCame second in the AES competition, has never been broken, and is barely used — because second place in a standardisation…
- TymnetA data network that began as Tymshare's way of reaching its time-sharing customers and ended up as one of the world's…
- Type class (trait in Rust, typeclass in Haskell)A mechanism for ad-hoc polymorphism — define a set of operations a type must support, implement them for different types…
- Type conversionTurning a value of one data type into another — either because the programmer asked for it, or because the language did it…
- Type erasureGenerics implementation where type parameters are removed at compile time. Java 5 (2004) chose this route for backward…
- Type objectA pattern that defines a "type" as data in an object rather than as a subclass, so new kinds can be created at runtime…
- Type systemThe rules a language has for which types exist and how they combine.
- Type-in programSoftware published as printed source code in computer magazines and books, for readers to key in by hand.
- TypeballThe interchangeable printing element of the IBM Selectric — a golf-ball-sized sphere carrying every character.
- Typebar printerA printing mechanism where every print position owns a bar carrying the full character set, raised into place and then…
- TypeformForms that ask one question at a time, smoothly animated like a conversation instead of a wall of fields — a deliberate…
- TypeORMTS-first ORM with decorator syntax — entity classes with @Entity, @Column. Standard in NestJS world.
- TypeScript (TS)JavaScript with static types — compiles to plain JS, catches bugs before runtime.
- TypesenseOpen-source search engine built for lightning-fast search-as-you-type with typo tolerance baked in — a lighter alternative…
- TypewriterThe mechanical ancestor of every printer and printing terminal — and the reason your keyboard is still called QWERTY.
- Typewriter artPictures typed one character at a time — the analogue ancestor of ASCII art, a century older than the computer.
- TypexBritain's own Enigma — same basic idea, fewer things for the operator to get wrong, and never read by the Germans.
- Typing indicatorThe animated dots ("…") that show the other person is composing a message. A little real-time signal that builds…
- TyposquattingRegister domains or package names that look like popular ones — googel.com, requestz instead of requests — and wait for…
- TypstModern typesetting system. Berlin startup, 2019. Goal: replace LaTeX with cleaner syntax + faster incremental compilation…
- X Premium (Twitter Blue)Twitter/X subscription. Pre-Musk (2021) Twitter Blue was $3 for bookmark folders + cosmetics. Musk era (2022+) made it $8…
U
- /dev/urandomLinux's device for cryptographically secure random numbers — the one you should use, whatever old man pages claim.
- u-bloxThe Swiss GPS module inside a surprising share of everything that knows where it is.
- U.2 SSDAn SSD form factor (SFF-8639) in a 2.5-inch enclosure carrying NVMe over PCIe — so NVMe performance but in a server-drive…
- U.S. RoboticsThe modem maker whose Courier sat in nearly every serious BBS, and whose Sportster sat next to everyone dialling in.
- UAC bypassSkipping the Windows elevation prompt without the user seeing anything. Microsoft does not count it as a vulnerability…
- UADEUnix Amiga Delitracker Emulator — plays the Amiga's obscure music formats by running the original replay routines on an…
- UARTUniversal Asynchronous Receiver/Transmitter — the classic asynchronous serial communication with two wires (TX and RX) and…
- UberDisrupted the taxi industry globally — first ridesharing, then Uber Eats, Freight, helicopters, parcels. Lost money for a…
- Uber EatsUber's food delivery app — launched 2014. Globally #2 after DoorDash in the US, but #1 in many other countries.
- Uber shaderA single large shader that compiles every material feature behind preprocessor switches, branches or static permutations…
- UberMUDAn early MUD server where all the game's rules lived in a programming language inside the world rather than in the server's…
- UbiquitiAmerican networking vendor that sold its way into homelabs and small businesses with tidy hardware, central management and…
- UbisoftFrench publisher from Brittany, founded by five brothers, best known for open worlds stuffed with towers to climb.
- UbuntuThe Linux distribution that made Linux usable for people who did not want to compile things.
- ucbvaxThe computer science VAX at UC Berkeley, which in the early '80s bridged ARPANET mailing lists into Usenet.
- UCIeUniversal Chiplet Interconnect Express — an open industry standard (2022) for how chiplets communicate die-to-die within a…
- UDE (Unix Desktop Environment)A late-1990s desktop environment that removed everything: no icons, no title bars, no panel, just thin frames and a…
- UDF (Universal Disk Format)OSTA filesystem that shed ISO 9660's cramped limits and became the standard on DVD, Blu-ray and rewritable CDs.
- UDLD (UniDirectional Link Detection)Protocol that detects a fibre link carrying traffic in only one direction. A fault that is unpleasant precisely because the…
- UDP (User Datagram Protocol)Lightweight transport with no reliability guarantees — fires packets and hopes for the best.
- UDP floodVolumetric DDoS: flood the victim's bandwidth or ports with UDP packets. Simple: spam UDP packets to random ports → server…
- UDP/TCP "ping"When ICMP is blocked — use TCP-SYN or UDP packet with an unusual port to measure reachability + RTT. Tools: hping3, nping…
- UEBAUser and Entity Behavior Analytics — security technology that builds a baseline of what's "normal" behavior for each user…
- UEFI (Unified Extensible Firmware Interface)Modern replacement for BIOS — boots the computer, finds the bootloader, handles Secure Boot.
- Ueli MaurerSwiss cryptographer at ETH Zurich who showed how far you can get without assuming anything is hard to compute.
- UFGATEGateway software that translated between FidoNet and UUCP, letting mail and newsgroups cross between the BBS world and…
- UFS (Universal Flash Storage)The flash storage standard in modern smartphones — successor to eMMC, much faster.
- UIKitApple's original framework for iOS interfaces — imperative, mature, and still the foundation under most large apps.
- UILMotif's declarative language for describing an interface's widget tree in a separate file rather than in C code.
- UIM/XThe Motif builder with a built-in C interpreter, so you could click a button and watch its callback run without compiling…
- UiPathThe Romanian startup that built software robots to click through other programs for you, and rode the RPA wave all the way…
- uk.*Britain's own Usenet hierarchy, with its own rules for creating groups and an argumentative culture that gave the Big 8 a…
- Úlfar ErlingssonIcelandic security researcher who co-invented control-flow integrity and later got Chrome to collect statistics under…
- ULID (Universally Unique Lexicographically Sortable Identifier)128-bit identifier: 48-bit timestamp + 80-bit random. Lexicographically sortable (IDs from the same ms sort in creation…
- ULT formatThe module format of UltraTracker, a DOS tracker built entirely around the Gravis UltraSound.
- Ultimate 64A new Commodore 64 motherboard with the entire original chipset recreated in an FPGA, designed to drop into a stock case.
- Ultimate SoundtrackerKarsten Obarski's 1987 program that invented both the MOD format and the pattern-grid paradigm — the ancestor of all tracker…
- UltraThe British designation for intelligence derived from decrypted German messages during the Second World War.
- UmbraFinnish occlusion-culling middleware that works out ahead of time what can hide what, so the engine doesn't draw everything…
- UmbracoA Danish open source CMS for .NET — the closest the Microsoft world gets to WordPress, with a far stricter content model.
- UMCUnited Microelectronics Corporation: Taiwan's first chipmaker and permanent runner-up to TSMC.
- UMX formatThe Unreal engine's music package — ordinary tracker modules wrapped in the game's own package format.
- unclutterA tiny X11 utility that hides the mouse pointer once it has sat still for a while, so it stops parking itself in the middle…
- Unconstrained delegationThe original Kerberos delegation from Windows 2000, where a server receives a copy of the user's ticket and can therefore…
- Undefined behavior (UB)C/C++ code whose behaviour is not specified — the compiler may do anything, including deleting the code.
- UnderfillThe epoxy drawn into the gap between a flipped die and its substrate. Without it the solder bumps crack, because silicon and…
- UndernetThe IRC network founded in 1992 as a calmer alternative to EFnet, and the first to offer a central service for registering…
- Underscore.jsJavaScript utility library from 2009 by Jeremy Ashkenas (the same person behind CoffeeScript and Backbone). Everything is…
- UndervoltingLowering the voltage on a CPU/GPU below the stock value to reduce heat + power without losing performance. Works because…
- Undo logMySQL/InnoDB's log of previous values, used for two things: to roll back (undo) a transaction, and to reconstruct older row…
- Uni-VibeA Japanese effect meant to sound like a Leslie speaker, which failed at that and became a sound of its own instead.
- UnicastOne packet, one sender, one recipient — the overwhelmingly common case that the other addressing modes are defined against.
- Unicast floodingWhen switch doesn't find destination MAC in table → sends frame to ALL ports (except incoming). "Unknown unicast flooding"…
- Unicity distanceHow much ciphertext you need before only one key yields readable plaintext.
- UnicodeUniversal standard for representing every character in every language — and every emoji.
- Unicorn startupA privately held startup valued at over $1 billion USD. The term was coined in 2013 by Aileen Lee (Cowboy Ventures) — back…
- UniFiUbiquiti's enterprise-grade prosumer ecosystem of networking gear. Access points, switches, routers, security cameras…
- Uniform gridSpatial partitioning that divides space into equal cells and bins objects into them, so collision tests only run against…
- UNIGINEAn engine from Tomsk that most people know as the Heaven GPU benchmark — and that in practice is used mainly for simulators…
- UnikernelSpecialised single-purpose VM image where the application and the necessary OS parts are linked into a single static binary…
- Union typeA type that can be one of several: string | number | null.
- UniselectorThe telephone exchange's rotary selector, stepping one notch per pulse — and the cheapest read-only memory the early…
- UNISOCA budget-segment Chinese chip designer that sits inside most of the world's cheapest smartphones without anyone knowing the…
- Unison (synth)A synth mode that plays several voices on the same note, slightly detuned against each other, so a single key sounds like an…
- UnisysThe merger of two mainframe pioneers, remembered mostly for making the web switch image formats.
- Unit record equipmentThe machine room that sorted, counted and printed punched cards without a computer anywhere in sight — sixty years of data…
- Unit testA test that verifies a small unit (usually a function) in isolation.
- UnitedLinuxFour smaller Linux vendors' attempt at a shared enterprise distribution to take on Red Hat – an alliance that lasted about a…
- UnitreeHangzhou company known for surprisingly cheap quadruped robots and humanoids — and for dancing robots on Chinese New Year TV.
- UnityDanish-founded cross-platform game engine — dominant in mobile and indie games, C# as the scripting language.
- Unity DOTSUnity's data-oriented track running alongside GameObjects: an ECS, a job system and a custom compiler for dense, parallel…
- UNIVAC IThe first computer you could order rather than build — and the one American newspapers turned into a synonym for "computer".
- Universal AudioAmerican company that built classic studio compressors, then sold software versions of them that would only run on its own…
- Universal hashingPicking the hash function at random from a family, so that any two given inputs collide with low probability no matter what…
- Universal linkAn ordinary HTTPS address that opens the app if installed and the web page otherwise — without the user noticing the…
- Universal MIDI Packet (UMP)The packet format that replaced MIDI's serial byte stream with 32-bit words — the container for both MIDI 2.0 and legacy…
- UnixOperating system from Bell Labs 1969 (Ken Thompson + Dennis Ritchie). Written in C (invented for Unix). Philosophy: small…
- Unix cryptThe password hash Unix used for decades: built on DES, limited to eight characters, and something nobody wants back.
- Unix InternationalThe AT&T and Sun counter-consortium of the Unix wars, formed in 1988 to defend System V Release 4 and OPEN LOOK against OSF…
- Unlimited bobsA demo effect that shows a seemingly endless number of moving blitter objects while drawing only one per frame.
- Unlogged tableA PostgreSQL table whose changes are never written to the transaction log. Substantially faster to write to, and empty after…
- UnoCSSAtomic CSS engine — Tailwind-compatible syntax but 10× faster. Anthony Fu (Vue/Nuxt core team), 2021.
- UNPIVOT (SQL)The opposite of PIVOT — turns columns into rows. Converts a wide table (a column per month: jan, feb, mar …) into a narrow…
- Unreal (demo)Future Crew's 1992 PC demo that won Assembly and showed a DOS box with a VGA card could play in the same league as the Amiga.
- Unreal EngineEpic Games' realistic-rendering engine — powers Fortnite, many AAA titles, film production (The Mandalorian), and…
- UnrealIRCdThe IRC server with the most features and the most small networks, and one of the more embarrassing backdoors in open-source…
- UnrealScriptThe Unreal engine's own object-oriented scripting language, home to game logic and mods for sixteen years until Epic removed…
- Unsupervised learningML where the data isn't labelled — the model finds patterns and structure on its own.
- UObjectThe root of Unreal Engine's class hierarchy, bolting reflection, garbage collection and serialisation onto C++ that never…
- UPCThe twelve-digit barcode that put the supermarket checkout on rails in the United States.
- Update methodThe pattern where each game object owns a method the game loop calls once per frame to advance it one time step.
- UPIIndia's open instant payment system, which within a few years became the world's largest by number of transactions.
- UPICIannis Xenakis's computer system for composing by drawing: lines on a tablet became pitch over time.
- Upload ratioThe BBS rule that you could download only so many files or kilobytes per upload — an early attempt to keep freeloaders in…
- UPS (Uninterruptible Power Supply)Battery backup between the wall socket and the equipment. The purpose is rarely to keep working through an outage but to…
- UpscalingMaking an image larger than the original — either by guessing intermediate values mathematically, or by letting a model…
- Upsert"Update or insert" — if the row exists: update. If not: create.
- UpstashServerless data platform that bills per request instead of per hour — Redis, Kafka and vector search with no server to run.
- UptimeThe fraction of time a service has been available — often expressed in "nines".
- Upward compressionDynamic range compression that lifts the quiet parts below the threshold rather than pushing the loud parts down.
- UPXThe Ultimate Packer for eXecutables — a free executable packer from 1996 that compresses programs so they unpack themselves…
- Urho3DA lean, MIT-licensed C++ 3D engine from Finland — the serious option for people who wanted a real engine but not an entire…
- URI vs URLURI = identifier (URN or URL). URL = identifier and how to reach it.
- URL (Uniform Resource Locator)The address to a resource on the web — what you type in the browser's address bar.
- USB (Universal Serial Bus)The universal standard for computer ports — power, data, video, audio through the same connector.
- USB Audio ClassThe standard that lets a USB sound device work with the operating system's own driver — what "class compliant" on the box…
- USB MIDIThe USB device class for MIDI, which lets a keyboard or synth plug in without its own driver and has replaced the five-pin…
- USB-C (USB Type-C)Reversible 24-pin connector — power, video, data, all in one hole.
- USB4A USB standard (2019) built on Intel's donated Thunderbolt 3 protocol. Uses only the USB-C connector, up to 40 Gbps (USB4…
- UsenetDecentralised discussion forum system from 1979 (Duke University) — predecessor of web forums, BBSes and Reddit. Newsgroups…
- USENET CookbookA cookbook assembled by Usenet's readers, published one recipe at a time through a moderated newsgroup in the 1980s.
- Usenet Death PenaltyUsenet's heaviest collective punishment: everything from a provider that wouldn't stop its spam simply stopped propagating.
- Usenet IIA 1997 attempt at a Usenet where every server promised to behave — a clean network running inside the dirty one.
- Usenet OracleA collective oracle by email, where every supplicant had to answer someone else's question before receiving an answer of…
- USENIXAn association for Unix and systems people whose conferences became one of the early meeting places of net culture.
- User spaceWhere ordinary programs run — with no direct hardware access, and each with its own protected address space.
- User-AgentHTTP header the browser sends — identifies type, version, OS.
- UsurperDark fantasy door game from 1993, written by Swede Jakob Dangarden, in which the goal was to seize the throne.
- Utah GLXThe first attempt to give XFree86 hardware-accelerated OpenGL, around 1999, with every drawing call routed through the X…
- UTF-8The dominant Unicode encoding — variable length, 1-4 bytes per character, backwards compatible with ASCII.
- Utility AIA decision model where every possible action is scored by a utility function and the agent picks the highest — or samples…
- UtimacoGerman maker of hardware security modules based in Aachen, one of a handful of players in a market where customers would…
- utzooThe Zoology department's machine at the University of Toronto, where Henry Spencer spent a decade saving Usenet to tape.
- uucicoThe part of UUCP that actually dialled the neighbour, logged in and moved the queued files in both directions.
- UUCPUnix-to-Unix Copy: machines that dialled each other by modem, often at night, and passed files, mail and news along in hops.
- UUCP Mapping ProjectThe volunteer effort that tracked which UUCP machines called which, so mail could find its way.
- uuencodeThe encoding that turned binary files into printable characters so they could survive email and Usenet, until MIME and…
- UUID (Universally Unique Identifier)128-bit identifier — extremely unlikely that two will be generated identically, even globally.
- UUID type128-bit unique identifier, stored as 16 bytes. Popular PK type for distributed systems (no central sequence needed). UUID v4…
- UUIDv7A UUID variant that begins with a millisecond timestamp and fills the rest with randomness. Standardized in RFC 9562 (2024)…
- UUNETThe non-profit set up to relieve one overloaded Usenet hub that ended up as one of the world's largest internet providers.
- UUPCUUCP for personal computers — what let a DOS box with a modem become a node of its own on Usenet and the email network.
- uuxUUCP's remote execution: a command queued to run on another machine the next time the modem called it.
- UV mappingAssigning every point on a 3D model a coordinate in a 2D texture, so a flat image can be laid onto the curved surface.
- UV scrollingMoving a texture's UV coordinates over time so the surface appears to move, while nothing in the geometry actually does.
- UV unwrappingFlattening a 3D model's surface onto a plane so a texture image can be painted onto it.
- uwmThe Universal Window Manager, default in X10 and the first releases of X11 until twm took over.
- UXAIntel's 2008 rewrite of EXA, built on the observation that integrated graphics has no memory of its own to move pixmaps into.
V
- Apple Vision ProApple's mixed reality headset. Launched in the US in February 2024 ($3499). Runs visionOS. Apple markets it as "spatial…
- Google Vertex AIGCP's unified ML/AI platform — training, deployment, AutoML, agents, Model Garden (foundation models including Gemini…
- HashiCorp VaultOpen source secret manager — central storage + dynamic credentials + crypto-as-a-service.
- V-HACDThe open-source library most game engines call when a concave 3D mesh has to become a handful of convex collision shapes.
- V-NANDSamsung's answer when flash cells could no longer be shrunk sideways: build upward instead.
- V2 (synthesizer)Farbrausch's software synth, small enough to live inside a 64k intro and good enough to sound like a proper studio.
- V8Google's JavaScript engine. Launched with Chrome 2008. Also powers Node.js, Deno, Bun, Cloudflare Workers, Edge. Lars Bak…
- VA panel"Vertical Alignment" — LCD panel type positioned between IPS (good color, worse contrast) and TN (fast, bad viewing angles)…
- vacation (Unix)The original out-of-office reply: a small Unix program that answered mail while its owner was away.
- VACUUM (Postgres)PostgreSQL maintenance that cleans up "dead rows" (dead tuples) left behind by MVCC after UPDATE/DELETE. Without VACUUM…
- Vacuum columnThe two vertical slots where mainframe tape drives sucked in a slack loop of tape, so starting and stopping didn't snap it.
- VACUUM FULLPostgreSQL command that rewrites a table entirely to reclaim disk space from dead tuples. Takes an ACCESS EXCLUSIVE lock…
- Vacuum tubeThe computer's first switch: a light bulb that could say yes or no, and that broke about as often as one.
- VAD (Voice Activity Detection)Detect when someone is talking versus silent in an audio stream — a critical step before speech recognition and in voice…
- Vadim LyubashevskyThe IBM Research Zurich cryptographer who co-designed both Kyber and Dilithium, the lattice-based algorithms NIST…
- VAE (Variational Autoencoder)Generative model that learns to compress data into a "latent space" and regenerate from it.
- VagrantTool for creating reproducible dev environments in VMs — vagrant up starts a configured VM.
- VAIOSony's PC brand that outlived Sony's exit from computers — now a small company of its own in Nagano.
- ValgrindA framework for dynamic binary instrumentation, best known for the Memcheck tool that finds memory errors in C and C++…
- Validating webhookKubernetes admission controller that APPROVES or REJECTS objects before persistence — but can't change them. Drives policy…
- ValkeyOpen-source fork of Redis 7.2.4 — started in March 2024 by AWS, Google, Oracle and several ex-Redis developers in response…
- ValtioProxy-based state — mutate directly (state.count++) as if it were a plain object, library detects via Proxy. Daishi Kato…
- Value noiseThe simplest lattice noise — random values at grid points, smoothly interpolated between — cheaper than gradient noise but…
- ValveThe Washington game studio that made Half-Life and then became PC gaming's store, checkout and delivery network rolled into…
- Valve Anti-Cheat (VAC)Valve's automated anti-cheat from 2002 — known for silent, delayed and permanent bans.
- Vamp pluginsA plugin format for audio analysis: audio goes in, data about the audio comes out, never new audio.
- Vanish modeA mode in Instagram/Messenger chats where messages are deleted automatically as soon as you leave the chat and close it. A…
- Vannevar BushThe man who built mechanical integrators, ran American wartime research and in 1945 described a reading machine that was…
- VantaKicked off the trend of automating SOC 2 — plugging into the cloud and watching security controls instead of the spreadsheet…
- Vapor chamberSealed thermal-transfer device: a flat-large heat-pipe with a wicking structure + working fluid. Effect: distribute heat…
- VaporwareA product announced, marketed and covered in preview articles — but never shipped.
- VariableNamed storage location holding a value — the most fundamental building block in nearly all programming languages.
- Variable jump heightThe jump rises higher the longer the jump button is held — a tap gives a small hop, a long press a full jump.
- Variable rate shadingLets the GPU shade a whole block of pixels with a single fragment-shader invocation wherever full resolution would not be…
- Variable-mu compressorA tube compressor that reduces gain by shifting the bias on a valve whose amplification factor, mu, changes with it.
- Variance shadow maps (VSM)A shadow map storing both depth and depth-squared so Chebyshev's inequality can estimate shadowing — letting the map be…
- Variant BeaufortThe variant Beaufort is the Vigenère cipher with the encryption and decryption directions swapped.
- VarispeedPlaying a recording faster or slower so that pitch and tempo change together, exactly as they do when you drag a tape.
- VarnishHigh-performance HTTP reverse proxy + cache. Poul-Henning Kamp (FreeBSD core), 2006. Written specifically for memory…
- VaronisThe security company that works out who can actually reach which files, and usually finds the answer is "everyone".
- VAST DataThe storage firm that bet everything on cheap QLC flash and an architecture where nothing is shared — then rebranded itself…
- Vault (HashiCorp Vault)A system for storing and handing out secrets — passwords, API keys, certificates — instead of keeping them in environment…
- VAXDEC's 32-bit machine, the standard computer of 1980s universities — and the yardstick everything else was measured against.
- vBulletinThe forum software that ran a large slice of the 2000s internet. It cost money, unlike phpBB, and was considered worth it.
- VCA (voltage-controlled amplifier)An amplifier whose gain is set by a voltage rather than a knob.
- VCA compressorA compressor that turns down gain with a voltage-controlled amplifier, giving fast, precise and fairly uncoloured dynamics…
- VCF (voltage-controlled filter)The analog synth's filter, with a cutoff set by a control voltage rather than just a knob, so the timbre can move while the…
- vcluster (virtual clusters)A complete Kubernetes cluster running inside a namespace of another cluster. The tenant gets their own API server and…
- VCO (voltage-controlled oscillator)The analogue synth's tone source, whose pitch is set by an incoming voltage.
- VCV RackA virtual Eurorack: modules, cables and voltages on screen, for the price of nothing rather than a used car.
- VcXsrvA free X server for Windows built straight from the X.Org code with Visual C++, which took over from Xming and was how you…
- VectorA list of numbers representing something in "space" — typically 768 to 3072 dimensions in modern AI models.
- Vector ballsIdentical shaded balls placed in 3D to trace out rotating shapes — cheap 3D before filled polygons were affordable.
- Vector clockPer-node-counter vector tracking logical time in distributed systems — lets you tell whether one event happened before…
- Vector databaseDatabase optimised for "find the N nearest vectors to this query vector" — the engine behind RAG, semantic search…
- Vector indexAn index for fast similarity search among high-dimensional vectors (embeddings) — "find the 10 nearest neighbors". The…
- Vector quantizationCompression technique for vector databases. Maps 1024-dim float vectors (~4 KB) to 8-32 byte codes via clustering. Enables…
- Vector search techniquesAlgorithms for approximate nearest neighbor (ANN): HNSW (hierarchical graph), IVF (clustered), DiskANN (disk-based). Plus…
- Vector synthesisA synthesis technique in which a joystick mixes four sound sources in real time, letting the timbre drift between them like…
- VeeamThe backup software that rode the virtualization wave by copying whole virtual machines instead of files.
- Vehicle physicsThe simulation that makes cars, bikes and trucks accelerate, lean and lose grip — from arcade drift to millimetre-exact…
- VeleroBacks up a Kubernetes cluster: both the objects in the API server and the contents of the volumes. Used as often to move…
- Velocity (MIDI)How hard a key was struck, measured as how fast it travelled and sent as a single number inside MIDI's Note On message.
- Vendor lock-inWhen switching vendors is so expensive or complicated that you're "stuck" — even as the price rises.
- VenonaProof that a provably unbreakable cipher breaks anyway, once whoever manufactures the key material is in a hurry.
- VeracodeCode review as a service, originally built on analysing compiled binaries instead of source.
- VerbatimFloppies and recordable discs from a company older than most of the formats it sold.
- VercelHosting platform optimised for modern JS frontends — builds every commit, deploys globally on the edge, free tier for hobby.
- Verified badgeThe blue (or other colored) check next to a name that originally meant the platform had confirmed the account is who it…
- VerifoneAmerican maker of card terminals: the grey box by the till that most people have typed a PIN into at some point.
- VeriSignThe company that first sold the web its trust in the form of certificates, then landed exclusive control of .com — the most…
- VeritasThe storage company whose Volume Manager and NetBackup ran under much of the Unix server room of the 1990s and 2000s.
- VerizonOne of the largest US carriers, formed in 2000 from what was left of the broken-up Bell System.
- Verlet integrationA way to step the equations of motion forward by storing the previous and current position instead of a velocity.
- Vern PaxsonBerkeley network researcher who built Bro (now Zeek) and co-wrote the classic analyses of internet worms.
- VeronicaThe search engine for all of Gopherspace: an index of menu titles from every Gopher server it could find.
- VersatecAmerican company that made electrostatic wide-format printers and plotters an engineering standard in the 1970s.
- Version controlThe system that makes people brave enough to change code — because every previous state is still there.
- Vert.x (Eclipse Vert.x)Event-driven toolkit for the JVM, started by Tim Fox in 2011 (then at VMware, later Red Hat). The Node.js model on the JVM…
- Vertex animation texture (VAT)A technique that bakes an animation's per-frame vertex positions into a texture, so a vertex shader can replay it with no…
- Vertex Buffer Object (VBO)An OpenGL buffer that stores vertex data in the graphics card's memory so it need not be shipped across from the processor…
- Vertex cache optimizationReordering a mesh's index list so recently used vertices stay in the GPU's small post-transform cache.
- Vertex colorA colour stored per vertex of a mesh and interpolated across the triangle — one of the oldest ways to colour geometry…
- Vertex displacementMoving a mesh's vertices in the vertex shader at render time — waves, flags, bending grass — without altering the stored…
- Vertex shaderThe program run once per vertex that determines where in the image it lands.
- Vertex skinningThe deformation step of skeletal animation: each vertex is moved by a weighted blend of its bones' matrices.
- Vertex snappingWhat happens when vertex screen positions are rounded to whole pixels: polygons twitch in little jumps the moment the camera…
- Vertex weldingMerging vertices that lie closer together than a tolerance into one point, to seal cracks and shrink the mesh.
- VerticaA column-store analytics database out of the Stonebraker camp; HP bought it in 2011 to meet the demand for fast reporting.
- Vertical blank (VBlank)The pause as the beam finishes the last visible line and travels back to the top — the only safe window to write graphics.
- Vertical Pod Autoscaler (VPA)A Kubernetes mechanism that automatically adjusts the SIZE of a pod — its CPU and memory requests/limits — rather than the…
- Vertical scaling (Scale up)Scale by upgrading to a bigger machine — more CPU cores, more RAM — instead of more machines.
- VESA VBEA standardized BIOS extension that provided uniform access to high-resolution graphics modes on PC hardware, freeing…
- Vesselin BontchevBulgarian virus researcher who documented the Bulgarian "virus factory" around 1990 and then spent decades taking malicious…
- veth (Virtual Ethernet pair)A pair of virtual interfaces that acts as a pipe: whatever is sent into one comes out of the other. The building block that…
- VEXVulnerability Exploitability eXchange — machine-readable format where the vendor states "this CVE in our SBOM does NOT apply…
- VFDThe blue-green glowing display in VCRs, microwave ovens and checkout terminals — a flat vacuum tube that has refused to die.
- VFSThe abstraction layer that makes open() and read() behave identically regardless of which filesystem lies beneath.
- VGM formatA logging format that records every write to a sound chip's registers with timing, so playback is a faithful re-run on an…
- VIA TechnologiesTaiwanese chip designer whose motherboard chipsets sat inside a large share of the world's budget PCs in the 1990s.
- ViberMessenger + VoIP app — Israeli startup 2010, bought by Rakuten 2014 for $900M. Big in Eastern Europe, the Philippines…
- VibratoA periodic wobble in pitch — what singers do with their throat and violinists with their hand.
- VIC cipherA Soviet pencil-and-paper spy cipher so well constructed that the FBI only read it after the spy defected and explained it…
- VIC-20Commodore's cheap 1981 home computer with 5 KB of RAM — the first computer to sell a million units.
- VIC-IIThe Commodore 64's video chip — sixteen colours, eight hardware sprites, and the raster tricks the whole demoscene was built…
- VICEThe Versatile Commodore Emulator — the open-source emulator that runs nearly all of Commodore's 8-bit family and that the…
- Victim cacheA cache (or cache policy) that catches data lines just evicted ("victimized") from a higher cache level, instead of…
- Victor MillerThe mathematician who in 1985, independently of Neal Koblitz, proposed building public-key cryptography on elliptic curves.
- Victor ShoupAmerican cryptographer behind Cramer–Shoup encryption, the generic group model and the NTL number theory library.
- Victor TechnologiesChuck Peddle's follow-up to the 6502 era — the Victor 9000 out-engineered the IBM PC but lost the standards war.
- Video feedbackDemo effect where the screen image is fed back into itself every frame, producing endless tunnels and lagging trails.
- Video game crash of 1983The North American games market fell by more than ninety per cent in two years — and the industry was written off as a…
- VideotexThe 1970s attempt to turn the television into a two-way terminal onto central databases — right idea, fifteen years early.
- View (database)A saved SELECT query that behaves like a table — runs the underlying query each time you SELECT from it.
- View frustumThe truncated pyramid of space a perspective camera can see — bounded by six planes, and anything outside them can be thrown…
- View onceA feature where an image or video can be opened exactly once and then disappears permanently — it can't be opened again…
- View spaceThe world re-expressed so the camera sits at the origin looking down a fixed axis — the space where "how far away" collapses…
- View Transitions APIBrowser API that photographs the page before and after a change and animates between them for you, including across a real…
- ViewKitSGI's C++ framework on top of Motif, which let IRIX applications be built from components with their own windows, dialogs…
- ViewMAXThe graphical shell bundled with DR DOS 5 and 6: a cut-down GEM that could launch DOS programs from icons but could not run…
- ViewportThe visible portion of a web page in the browser window. <meta name="viewport" content="width=device-width…
- Viewport metaHTML meta tag that controls how a mobile browser scales content. <meta name="viewport" content="width=device-width…
- viewresA graphical map of the Athena widget class hierarchy, showing the resources each class inherits and adds.
- Vigenère cipherA polyalphabetic cipher considered unbreakable for three centuries, until someone realised the key length can be computed…
- VignetteDarkening the image toward its corners — in real lenses an optical defect, in games a deliberate device to pull the eye…
- Vim (Vi IMproved)A modal text editor written by Bram Moolenaar in 1991, originally for the Amiga. An extension of vi (Bill Joy, 1976) that…
- VimeoPremium video hosting — the "artistic" alternative to YouTube, today mostly B2B video SaaS.
- Vincent RijmenBelgian cryptographer who co-designed Rijndael with Joan Daemen, the algorithm that became AES.
- VineShort-looping-video app, 6 seconds per clip. Launched 2013, bought by Twitter pre-launch, killed 2017 due to Instagram +…
- Vinod VaikuntanathanMIT cryptographer who helped move fully homomorphic encryption off exotic assumptions and onto ordinary lattice problems.
- Vint CerfDesigned, with Bob Kahn, the protocols that let different networks talk to each other — which is precisely what the internet…
- Virgil GligorRomanian-born researcher who gave denial of service a definition long before it acquired a second D.
- Virgil GriffithThe hacker behind WikiScanner and Tor2web who was later imprisoned over a talk in Pyongyang.
- Virtual analog synthesisDigital synthesizers that compute oscillators, filters and envelopes so they behave like analogue circuits.
- Virtual audio cableA pretend audio device in the operating system that takes sound from one program and hands it to another as an input.
- Virtual bindings (Motif)Motif's layer between physical keys and widget behaviour: the code listens for osfCancel and osfHelp, not Escape and F1, and…
- Virtual desktopSeveral desktop surfaces to switch between, so windows for different tasks don't end up in one heap.
- Virtual DOMIn-memory representation of the DOM that the framework diffs against the previous render, then applies minimal changes to…
- Virtual DOM diffingThe technique (popularized by React) where the UI is described as a lightweight "virtual" DOM tree in memory; on a change a…
- Virtual KubeletA node in the cluster that doesn't exist. It registers as an ordinary node but forwards the pods somewhere else entirely…
- Virtual machine (VM)Simulated computer running on a physical host via a hypervisor. Own OS, own resources, isolated from host and other VMs.
- Virtual memoryThe illusion that every process has all of memory to itself, starting at address zero.
- Virtual shadow mapAn Unreal Engine 5 shadow system that behaves like one enormous shadow map but only renders the parts you can actually see.
- Virtual texturingA huge texture surface is split into pages, and only the ones actually visible are streamed into a small physical cache.
- VirtualBox / VMware WorkstationType-2 hypervisors for the desktop — run a VM on your normal laptop/computer for testing.
- VirtualizationRunning multiple virtual machines (VMs) on a single physical computer via a hypervisor.
- VirtuaWinThe open-source virtual desktop for Windows: a small tray program that has been hiding and showing windows since around 2000…
- VisaThe largest card network outside China, which neither issues cards nor lends money and makes its living moving messages…
- VishayAmerican maker of discrete semiconductors and passive components, founded by a Holocaust survivor.
- Visi OnVisiCorp's windowing environment for the IBM PC, shown in 1982 — the first mouse-driven GUI for the platform.
- Visibility bufferStores just a triangle ID per pixel instead of a fat G-buffer, resolving material shading in a later full-screen pass.
- Visibility graphA graph whose nodes are obstacle corners and whose edges join corners that can see each other — the shortest path through it…
- Visibility mapTwo bits per data page saying whether everything on it is visible to everyone, and whether everything is frozen. A tiny…
- Visibility polygonThe polygon covering everything an observer can see from a given point, bounded by the scene's obstacles.
- VisibilityNotifyThe X11 event telling a program whether its window is fully visible, partly covered or completely hidden by other windows…
- VisiCorpThe publisher of the first spreadsheet, briefly the biggest software company in microcomputing, and gone within five years.
- Vision coneAn AI agent's field of view modelled as a cone — an angle and a range ahead — within which a target in clear sight counts as…
- VismaA Norwegian group that has bought up a large share of the Nordic and European local accounting and payroll software market.
- VisplaneThe Doom engine's container for a visible patch of floor or ceiling — and the error message that taught a generation of…
- Visual (X11)X11's description of how pixel values turn into colours on a given screen, split into six classes that mirror 1980s graphics…
- Visual scriptingBuilding program logic by wiring nodes together in a graphical editor instead of writing code as text.
- Visual StudioMicrosoft's full-size development environment for Windows — not to be confused with VS Code, which shares only the brand.
- Visual Studio CodeMicrosoft's free editor — launched 2015, built on Electron + TypeScript. Drove LSP, DAP forward and became the world's…
- Vital (synthesizer)A free wavetable synth from 2020 that made paying for Serum noticeably harder to justify.
- Vitaly ShmatikovSecurity researcher with a habit of finding the leak in systems everyone else had already declared safe.
- ViteJS frontend tooling. Evan You (Vue creator), 2020. Native-ESM-based dev server (no bundling needed for dev), Rollup for…
- VitessA scaling layer for MySQL, built at YouTube in 2010 when one database stopped being enough. It handles sharding so…
- VitestTest runner built on top of Vite — Jest-compatible API, native ESM, blazing watch mode.
- Vivaldi TechnologiesThe browser company Opera's co-founder started once Opera stopped being the browser he wanted to use.
- VKRussia's answer to Facebook, founded by Pavel Durov — who was pushed out, started Telegram, and left the network to owners…
- Vladimir LevinRussian computer technician who moved roughly ten million dollars out of Citibank's cash-management system from St…
- VLAN (Virtual LAN)Logical division of a physical network — guest Wi-Fi and office network can share a switch but stay isolated.
- VLAN hoppingAn attack where an attacker on one VLAN manages to send traffic into another VLAN — thereby bypassing the segmentation meant…
- VLAN trunkSwitch-port configuration that carries multiple VLANs over the same physical link via 802.1Q tagging. Each frame gets a…
- VLCThe media player with the traffic cone that plays anything you throw at it, with no codec packs required.
- VLIWVery Long Instruction Word — a CPU architecture where every instruction packs multiple operations to be executed in…
- vLLMHigh-throughput inference server for LLMs — the core innovation is PagedAttention, which manages the KV cache like virtual…
- VLM (Vision-Language Model)A model that handles both images and text — "sees" an image and answers questions about it.
- VLSI TechnologyThe ASIC house that co-founded ARM and manufactured the very first ARM chips.
- VM (Virtual Machine)A virtual computer that runs on top of a physical one via a hypervisor.
- VM escapeWhen code inside a virtual machine gets out to the host or the hypervisor. It's the attack the entire public cloud model…
- vmsnet.*An alternative Usenet hierarchy for users of DEC's VMS — the Unix world's network, used by the other camp.
- VMwareSolved virtualisation on x86 when the architecture wasn't built for it — and thereby made the whole server consolidation…
- VMware ESXiThe bare-metal hypervisor that defined enterprise virtualization. Installed straight onto the server with no underlying…
- VNCThe remote-screen system from Cambridge in 1998 that ships pixels rather than drawing commands, which is why its RFB…
- VNETIBM's internal worldwide network, built on the same RSCS and NJE technology that later carried BITNET.
- Vnode (virtual node)The technique of having each physical node be responsible for many small segments ("virtual nodes") on the consistent hash…
- VocaloidYamaha's singing synthesizer: type in notes and lyrics, get back a voice that sings them.
- VocoderBell Labs' discovery that speech can travel as a dozen measurements of energy and pitch rather than as a waveform — a…
- VodafoneBritish mobile operator that started as a subsidiary of a defence electronics firm and grew into one of the world's largest.
- Voice coil actuatorThe moving-coil motor that swings the head-arm across the disk, named for the identical mechanism in a loudspeaker.
- Voice messageRecorded audio message in chat. WhatsApp + Telegram popularized it ("hold mic button to record"). Standard in Latin America…
- Voice roomLive audio chat format with moderator + listener roles. Classic format: speakers on "stage" talk, audience listens and can…
- Voice stealingWhat a synth does when every voice is busy and a new note arrives anyway: it grabs one that is already sounding and reuses…
- Voice VLANA separate VLAN for IP phones, so voice traffic is kept apart from data traffic on the same physical cable. It lets a phone…
- VoicemeeterA virtual mixing desk for Windows that takes audio from both hardware and applications and sends it to any combination of…
- VoIP (Voice over IP)Phone calls over the internet instead of analog telephone lines.
- VoltDBIn-memory ACID SQL database designed for 100k+ TPS. Michael Stonebraker (Ingres + Postgres + many others), 2009. "NewSQL"…
- VoLTEVoice calls as data packets over the 4G network instead of via the old circuit-switched technology.
- Volumetric fogModels fog as a participating medium sampled into a camera-aligned 3D grid, accumulating in-scattered light per cell.
- Volumetric lightingLight rendered as though it scatters in the air itself — visible shafts and haze rather than just a lit surface.
- VolvelleRotating paper discs riveted in layers that worked out moon phases, feast days and ciphers — an analog computer made of…
- Von Neumann architectureThe idea that instructions and data live in the same memory — what made the computer general-purpose and gave it its…
- VonageThe American broadband phone company that swapped home phones for APIs and ended up owned by Ericsson.
- VorbisThe open audio codec written to get out from under MP3 licensing — usually wrapped in Ogg, hence "Ogg Vorbis".
- Voronoi diagramA partition of the plane into cells, one per seed point, where each cell holds everything closest to that seed.
- Voronoi fractureThe go-to way of breaking a model into believable shards: scatter points, and let each point's Voronoi cell become a piece.
- Vortex TrackerWindows tracker for writing AY chiptunes for the ZX Spectrum and other 8-bit machines.
- Vote manipulationArtificially inflating or deflating a post's votes with fake accounts, bots, bought votes, or coordinated groups — to rig…
- VotediskThe floppy holding every competition entry, handed out at a demoparty so attendees could vote the winners.
- VotesheetThe ballot at a demoparty where attendees rank the entries in each compo and pick the winners.
- VoxelA volume element — one sample on a regular 3D grid, the volumetric counterpart to a 2D pixel.
- Voxel art3D art created by stacking small cubic voxels (volume pixels), like pixel art in three dimensions.
- Voxel cone tracingReal-time global illumination that voxelises the scene and marches a few cones through the mip-mapped voxel volume.
- Voxel landscapeRolling terrain drawn without a single polygon — a heightmap read column by column with a ray from front to back.
- Voynich manuscriptAn illustrated fifteenth-century book in a script nobody can read — a cipher, an unknown language or an elaborate hoax.
- VP9Google's royalty-free video codec — YouTube's workhorse for a decade, and the rehearsal for AV1.
- VPAVertical Pod Autoscaler — Kubernetes add-on that recommends (or auto-updates) pod resources (CPU/memory requests) based on…
- VPC (Virtual Private Cloud)Your own logically isolated network in a public cloud — with your own IP ranges, subnets, routing.
- vPC (Cisco)Cisco Nexus feature: two switches form vPC domain, server LAG can terminate on both. Cisco version of MLAG. Standard in…
- VPC Endpoint (PrivateLink)Private connection to AWS services without going via the public internet or NAT Gateway — saves money and keeps traffic…
- VPC peeringConnect two VPCs privately — as if they were the same network, without going over the internet.
- VPLS (Virtual Private LAN Service)A carrier service that makes geographically scattered offices behave as though they sat in the same network switch. A…
- VPN (Virtual Private Network)An encrypted tunnel between your device and a server elsewhere — all your traffic goes through it.
- VPS (Virtual Private Server)A VM with root access that a hosting provider sells cheaply. The basis of all "rent-a-Linux" hosting. $5–20/month for basic…
- VQEA hybrid algorithm for finding a molecule's lowest energy state — the quantum part computes, the classical part tunes the…
- VR (Virtual Reality)Fully immersive 3D environment via a headset that covers your vision. Distinct from AR (overlays digital on real). The…
- VRAM (Video RAM)Memory on the graphics card — determines how big ML models you can run locally and how high-res textures you can load in…
- vRAN (Virtualized RAN)RAN software runs on commodity server hardware (x86) instead of proprietary baseband units. Cloud-native, container-based…
- VRFVirtual Routing and Forwarding — multiple independent routing tables in the same router. Enables multi-tenant: customer A's…
- VRM (Voltage Regulator Module)The power circuit on the motherboard that converts the PSU's 12V to the exact voltages the CPU/GPU want.
- VRM stages (phases)VRM design: the number of power stages that convert 12V to 1V for the CPU. More stages = more current handling + cooler…
- VRRPVirtual Router Redundancy Protocol — two or more routers share a virtual IP. The master announces, backups take over on…
- VS Code (Visual Studio Code)Microsoft's free source code editor. Electron-based, TypeScript-written. Launched 2015. Today the dominant editor — Stack…
- VSPA C64 trick that scrolls the entire screen sideways for free by nudging the VIC-II's internal video counter.
- VSTVirtual Studio Technology — Steinberg's interface that lets audio effects and software instruments from anyone run inside…
- VsyncHolding off the frame buffer swap until the display has finished its refresh — cures tearing, but at a cost.
- VT-x & AMD-VCPU extensions that make hardware-assisted virtualization possible — without them hypervisors have to emulate, which is…
- VT100DEC's 1978 video terminal, whose escape codes became the language almost every terminal window still speaks.
- VTuber (Virtual YouTuber)A streamer who performs as an animated avatar instead of on camera. The avatar follows facial expressions and movement in…
- vtwmVirtual twm: twm with a desktop bigger than the screen and a miniature map for getting around it.
- VU meterThe needle meter that shows average level rather than peaks — slow on purpose, and both loved and misunderstood for it.
- Vue Composition APIVue 3-introduced alternative to Options API — use hooks-like ref, reactive, computed in a setup() function or <script setup>.
- Vue.jsProgressive JavaScript framework. Evan You (ex-Google AngularJS team) released 2014. Single-file components (.vue), reactive…
- VuexOfficial state management library for Vue 2 + 3 — Flux-inspired (state, mutations, actions, getters). Replaced by Pinia in…
- VulkanModern low-level graphics + compute API from Khronos, 2016. Successor to OpenGL. More control, less overhead, better suited…
- VultrThe cloud provider for people who want a virtual server in a minute and an invoice they can actually read.
- VUPENA French security firm from Montpellier that openly sold undisclosed vulnerabilities to governments and turned the exploit…
- VWSDEC's own window system for the VAXstation under VMS in the mid-1980s, with the UIS library doing the graphics, replaced by…
- VXAEcrix's 1999 helical-scan tape that wrote data as addressed packets instead of long tracks — more fault-tolerant than QIC…
- VXLANL2-over-UDP tunnel protocol — extends Ethernet segments across L3 networks. The standard for modern data centre overlays.
- VXLAN-EVPNModern datacenter fabric: VXLAN (data plane, L2-over-UDP overlay) + EVPN (control plane, BGP-based MAC distribution)…
- VxRailDell EMC's hyperconverged appliance that bundles the VMware hypervisor, software-defined storage and servers into a single…
W
- _WIN_ hints (GNOME)GNOME 1's own root-window properties for talking to the window manager – layers, workspaces, sticky – which lived for two…
- AI watermarkInvisible pattern in AI-generated text/image so it can be detected later.
- Subreddit wikiA wiki section attached to a subreddit, where the community collects lasting information — FAQ, rules, guides, resource…
- W Window SystemThe Stanford system X was named after, quite literally: the next letter of the alphabet.
- W-bufferA depth buffer that stores distance from the camera linearly instead of the hyperbolically distributed z/w a normal Z-buffer…
- WacomThe Japanese company whose battery-free pen turned its name into a common noun among illustrators.
- WAD (Doom)The Doom engine's archive format — "Where's All the Data?" — and the reason the game had a mod scene before the word existed.
- WAF (Web Application Firewall)Firewall at the application layer — inspects HTTP traffic and blocks SQL injection, XSS, bot traffic.
- WaferSilicon disk 300 mm (12 inch) on which tens to hundreds of chips are created at once. Standardized since ~2000. Plan to move…
- Wafer yieldThe proportion of working chips out of all those made on a silicon wafer. Since defects are unavoidable, yield largely…
- WaffleTom Dell's BBS package for DOS, unusual in speaking UUCP natively and hooking a hobby board straight into Usenet.
- Wah-wah pedalA resonant band-pass filter whose centre frequency is swept by foot, making the guitar sound like a voice saying "wah".
- WAI (Web Accessibility Initiative)W3C initiative for web accessibility. Founded 1997 by Tim Berners-Lee. Publishes standards: WCAG, ARIA, ATAG, UAAG.
- WaimeaThe window manager David Reveman wrote before Xgl and Compiz: Blackbox styles with antialiased text and translucency through…
- WAISWide Area Information Servers — networked full-text search with ranked results, built before there was a web to search.
- WAL (Write-Ahead Log)The technique that gives databases durability (D in ACID): write to a sequential log first, then to the actual data file.
- WAL (Write-Ahead Log)Write-Ahead Logging — the database writes changes to a sequential log BEFORE applying them to the data files. Guarantees…
- WAL rotationThe management of the write-ahead log's segment files: when a segment fills up it's swapped for a new one, and old segments…
- wal_levelThe setting deciding how much information PostgreSQL writes into the transaction log. Changing it requires a restart, which…
- wall (Unix)"Write all": the command that prints a message straight onto every logged-in user's terminal at once.
- Wallace EckertThe astronomer who showed that accounting machines could do celestial mechanics — and who, the name notwithstanding, was no…
- Walsh–Hadamard transformA fast transform that computes the correlation with every linear function at once, and the workhorse behind much of linear…
- Walter BrattainThe experimental physicist with his hands in the apparatus when the first transistor amplified a signal in 1947.
- Walter TuchmanThe IBM engineer who led the effort to turn Lucifer into DES, then worked out how DES could outlive its own key length.
- WAN (Wide Area Network)A network spanning large geographic distances — the opposite of a LAN.
- Wang LaboratoriesThe company that turned word processing into an office machine, then failed to notice the personal computer doing the same…
- Wang tilesSquare tiles with colour-coded edges that may only abut where the colours match — a 1961 mathematical object repurposed to…
- WANK wormThe worm that tore through NASA's DECnet network in October 1989 carrying an anti-nuclear message — often called the first…
- War dialingHaving a modem call thousands of phone numbers in sequence to find the ones that answer with a carrier tone.
- War drivingDrive around with GPS + WiFi scanner to map wireless networks. Term coined 2001 by Pete Shipley (after the 1983 film…
- Ward BeullensBelgian cryptographer whose 2022 paper "Breaking Rainbow Takes a Weekend on a Laptop" did exactly what the title promised.
- Ward ChristensenAmerican programmer (1945–2024) who wrote XMODEM and, with Randy Suess, the first BBS.
- WarezPirated software distributed by organised scene groups — a subculture with its own rules, its own hierarchy and no profit…
- Warm startingSeeding an iterative solver with last frame's impulses instead of starting from zero, so a stack of boxes settles instead of…
- WarpModern terminal — Rust + GPU-rendering, blocks of input/output instead of an endless scrollback, integrated AI command help.
- Warp markersPins that fix a point in an audio file to a specific bar and beat on the DAW's grid, so the audio between them is stretched…
- WarpPointerThe X11 request that moves the mouse pointer on the user's behalf — technically trivial, socially fraught.
- WasabiA Boston company selling S3-compatible storage at a flat price per terabyte, which has made not charging for egress its…
- WASAPIWindows Audio Session API — the audio interface that arrived with Windows Vista and, for the first time, gave applications a…
- WASIWebAssembly System Interface — a standardised API that lets Wasm modules talk to "the system" (files, sockets, clock) in a…
- WatchGuardThe Seattle company behind the bright red firewall box sitting in the supply closet of countless small businesses.
- Water coolingCooling where liquid moves heat away from CPU/GPU to a radiator with fans.
- Water effectA rippling water surface computed from a simple neighbour-average — one of the 90s' most copied demo effects, and one of the…
- Water integratorA Soviet computer that solved differential equations using water in connected vessels — the level was the variable and the…
- Watering hole attackCompromise a website your target visits regularly — instead of attacking the target directly. Like the lion waiting at the…
- Watermarking attackAn attack on CBC-mode disk encryption that lets someone prove a particular file sits on an encrypted disk without knowing…
- Wau HollandGerman journalist and hacker who co-founded the Chaos Computer Club in 1981 and gave the hacker ethic a social conscience.
- WAVMicrosoft and IBM's 1991 audio file format — in practice a thin envelope around raw PCM, which is exactly why every program…
- Wave field synthesis (WFS)Spatial audio that rebuilds the actual sound wave with hundreds of loudspeakers instead of tricking the ear with a stereo…
- Wave function collapseA procedural-generation algorithm that assembles a large output from small tiles by repeatedly fixing the most-constrained…
- WavefoldingDistortion in which the part of the waveform that hits the ceiling is folded back down instead of being chopped off.
- WaveLabSteinberg's mastering editor, where the end product is a finished disc or file rather than a mix.
- WaveNetDeepMind's 2016 neural network that generates audio one sample at a time, and made machine voices noticeably less…
- Waves AudioIsraeli company behind one of the first commercial audio plugins, and behind a sale that has been running more or less ever…
- WaveshapingDistortion as a pure function: every sample value goes through a curve, and the shape of the curve decides which harmonics…
- Wavetable SynthesisA synthesis method that reads precalculated waveforms sequentially, where playback speed determines pitch, offering cheap…
- WaylandModern display server protocol for Linux. Kristian Høgsberg, 2008. Replacement for X11 (X.Org). Default in Fedora, Ubuntu…
- WaypointA node in a hand-placed or generated graph marking a walkable spot; the classic pathfinding method before the navmesh.
- WaZOOThe session protocol Opus brought to FidoNet in 1986, best remembered for letting one node request files from another.
- WCAG (Web Content Accessibility Guidelines)The international standard for web accessibility — levels A, AA (the norm), AAA (strict).
- Weak bitsA copy-protection trick where bits were deliberately written with unstable magnetisation, so they read differently on each…
- Weak cryptoUse of cryptographic algorithms that are broken or should-be-avoided: MD5 (collision attacks 2004), SHA-1 (collision 2017)…
- Weak IVAn initialisation vector that leaks information about the key, which made WEP vulnerable to the FMS attack.
- Weak keyA key that, for structural reasons, makes a cipher weaker than it should be and therefore has to be excluded.
- Wear levelingAn SSD technique that distributes writes evenly across all NAND cells so no individual blocks wear out prematurely. Since…
- WeaveworksThe London company that coined GitOps, gave away its best product and closed down while that product carried on.
- WeaviateVector database written in Go from the Netherlands — GraphQL API, modular vectorizers, multi-tenancy.
- Web Audio APIThe browser's audio engine: a graph of nodes that generate, filter and mix sound in real time from JavaScript.
- Web ComponentNative browser standard for building your own HTML elements: <my-widget>.
- Web componentsA set of web standards for building reusable, encapsulated, framework-agnostic HTML elements. The umbrella term covers three…
- Web crawlerA program that fetches a page, extracts the links and does it again — until the internet runs out, which it never does.
- Web Crypto APIBrowser-built-in crypto API accessible via window.crypto.subtle. Promise-based. Supports AES, SHA, RSA, ECDSA, ECDH, HKDF…
- Web Locks APIBrowser API for coordinating critical sections across tabs/workers from the same origin — like a mutex that lives outside…
- Web MIDI APILets a web page talk directly to MIDI devices plugged into the computer — keyboards, synths, control surfaces.
- Web PushBrowser API for push notifications from a web app to the user — even when the tab is closed. Requires a Service Worker +…
- Web Share APIBrowser API to trigger the OS's native share sheet — the user picks the destination (SMS, Mail, AirDrop, any app) instead of…
- Web shellA script (PHP, ASPX, JSP) that gives the attacker a command shell over HTTP — after initial access.
- Web WorkerBrowser API for running JavaScript in a background thread, separate from the main thread. Prevents heavy computation (image…
- Web WorkersBackground threads in the browser — heavy computation without blocking the UI.
- Web3The idea of a web where users own their data and identities through blockchain technology rather than through accounts with…
- WebAssembly (Wasm)Portable binary instruction format for a stack-based VM — runs in all modern browsers, also server-side via Wasmtime/Wasmer.
- WebAuthnWeb standard for passwordless / hardware-key authentication — the basis for passkeys in the browser.
- WebCodecsLow-level API for video/audio encoding and decoding in the browser — direct access to hardware codecs without going through…
- WebDAVThe extension that turns HTTP into a filesystem — read, write, move and lock files over the web.
- WebexThe video-meeting platform that ruled the corporate world for a decade before Zoom ran away from it.
- WebFingerThe protocol that makes @name@server.com resolvable. Standardized in RFC 7033. Without it, fediverse addresses would be URLs…
- WebflowDesigner builder that generates clean HTML/CSS/JS — the bridge between no-code and code. Default choice for design-heavy…
- WebGLJavaScript API giving access to the GPU from an HTML5 canvas. Based on OpenGL ES 2.0. Standardized by Khronos in 2011.
- WebGPUModern GPU API in the browser — successor to WebGL, maps onto Vulkan/Metal/DirectX 12.
- WebhookHTTP callback: a server calls your endpoint when something happens — instead of you polling.
- WebKitApple's open-source rendering engine. Forked from KDE's KHTML in 2001. Powers Safari, all iOS browsers, Mail, App Store, and…
- WebMGoogle's open container format for web video — a deliberately restricted subset of Matroska, free of licence fees.
- webOSPalm's elegant 2009 Linux phone OS that HP bought, killed off — and that today survives inside LG's TVs.
- WebPGoogle's image format. Launched 2010. Lossy + lossless mode + alpha + animation. 25–35% smaller than JPEG at similar…
- WebpackThe established JS bundler — takes your hundreds of JS/CSS/image files and packages them into a few optimised bundles.
- WebringHomepages linked in a circle, each carrying a small navigation box with "previous", "next" and "random". The search engine's…
- WebrootA security company from Boulder, Colorado, that went from wiping browser history to building one of the first cloud-based…
- WebRTC (Web Real-Time Communication)Peer-to-peer video, audio and data between browsers — without a plugin.
- WebsenseThe web filter that spent the 2000s standing between office workers and everything fun on the internet.
- WebSocketA protocol for two-way real-time communication between browser and server.
- WebSocket APIA web API for a persistent, bidirectional connection between browser and server. Unlike HTTP's request-response model, a…
- WebTransportBrowser API over HTTP/3 + QUIC that gives you both bidirectional reliable streams and unreliable datagrams — like WebSocket…
- WebvanThe online grocer that built the warehouses for a customer base it never got.
- WebViewA browser embedded as a view inside an app — what appears when you open a link inside Instagram rather than in Safari.
- WebVTTThe text format behind subtitles on the web — readable in a plain text editor, which is the entire point.
- WeChat (微信 / Weixin)China's everything app — messaging, payments, taxis, doctor bookings, an in-app "mini-program" app store. 1.3+ billion users.
- WeeChatA terminal chat client started in 2003. The name stands for "Wee Enhanced Environment for Chat" and describes the ambition…
- Wegman–Carter MACA recipe for message authentication: a fast universal hash plus a fresh one-time mask for every message.
- Wei DaiThe cypherpunk behind b-money, one of the proposals cited in the Bitcoin white paper, and the Crypto++ library.
- Weighted blended OIT (WBOIT)An approximation of order-independent transparency that weights each fragment by depth and blends additively, so no sorting…
- Weighted ECMPDistributing traffic across several paths in proportion to what they can actually carry, instead of splitting evenly between…
- WeightsThe numbers inside a neural network that determine its behaviour — what training actually adjusts.
- WeitekThe floating-point chip maker that was faster than Intel's — until Intel baked the math unit into the 486.
- Weld jointA joint that tries to hold two bodies perfectly still relative to each other, as if welded — in practice always slightly…
- WellfleetThe router that seriously challenged Cisco before a merger fumbled the lead away.
- Wendy NatherSecurity practitioner and analyst who coined the "security poverty line" — the idea that many organisations can't afford…
- Wendy SeltzerAmerican lawyer who built a public archive of takedown demands and later pushed security and privacy into web standards.
- Wenke LeeGeorgia Tech security researcher who brought data mining into intrusion detection and then went botnet hunting.
- WEPWi-Fi's first stab at encryption, which promised the privacy of a cable and delivered roughly the privacy of an unplugged…
- WerkkzeugFarbrausch's demo tool, in which textures, meshes and scenes are built from stacked operators instead of stored as data.
- Werner KochGerman programmer who has spent more than a quarter of a century as lead maintainer of GnuPG, the encryption tool much of…
- Western DigitalA Californian chipmaker that became a hard drive giant almost by accident, by way of the controller card sitting between the…
- Western ElectricThe Bell System's factory: for a century it built nearly every phone and switch in America, and nobody was allowed to buy…
- WestonWayland's reference compositor: the program in which Kristian Høgsberg showed the protocol worked, and which has been a test…
- Westwood StudiosThe Las Vegas studio that wrote the template for real-time strategy and was then shut down by its owner.
- Wet/dry mixThe balance between the processed and unprocessed signal in an effect — one knob that decides whether the voice is in the…
- WFC screenThe BBS software's idle mode — "Waiting For Caller" — sitting on the sysop's monitor while the modem waited for the next…
- wgetGNU CLI for downloading files over HTTP/HTTPS/FTP. Hrvoje Nikšić, 1996. Supports recursive mirroring of entire sites…
- WharfAfterStep's dock: a column of square buttons along the screen edge that launched programs, swallowed small status applets…
- WhatsAppThe world's most-used messaging app — started in 2009 by Jan Koum and Brian Acton (Yahoo! veterans), bought by Facebook in…
- WhatsApp BusinessMeta's business version of WhatsApp — free app for small businesses + WhatsApp Business API (paid, via partner) for…
- WhatsApp channelA one-way broadcast feature in WhatsApp (2023, Meta). Organizations and celebrities post updates that followers see in a…
- WhatsApp groupWhatsApp's group chat feature. Lift from 100 to 256 to 1024 members over the years. Admins can restrict "only admins can…
- WHATWGWeb Hypertext Application Technology Working Group. Founded 2004 by Apple, Mozilla, Opera as a reaction to W3C's XHTML…
- WHDLoadAn Amiga system that lifts floppy-based games and demos onto a hard disk or emulator.
- Wheel colliderA specialized collider that models a vehicle wheel as a downward raycast rather than a rolling cylinder.
- Wheel jointA compound joint for vehicle wheels in 2D: free rotation plus a sprung suspension along one axis.
- Wheeler jumpThe trick that let you jump into a routine and still find your way home — the subroutine call, invented in 1949.
- WhirlpoolA 512-bit hash function from 2000, built on a modified AES-style cipher by one of AES's own designers.
- WhirlwindBuilt to answer while the pilot was still sitting in the simulator — and it invented real-time computing on the way.
- WhisperOpenAI's speech recognition model, released in September 2022 with open weights under the MIT licence. It made high-quality…
- WhisperXA wrapper around Whisper that adds word-level timestamps via "forced alignment", plus speaker diarization via pyannote — and…
- White noiseA random signal with equal energy per hertz across the whole spectrum — which is exactly why the ear hears it as bright and…
- White-box cryptographyCryptography meant to hold even when the attacker can read the program's memory and control its execution.
- WhitespaceCharacters that appear as empty space: space, tab, newline, carriage return, vertical tab. In HTML/CSS, multiple whitespace…
- Whitfield DiffieSolved, with Martin Hellman in 1976, the problem thought unsolvable: how two parties agree on a secret key over a line…
- whoisA protocol and tool for looking up who registered a domain name or an IP block. Among the oldest services on the internet…
- WHOIS++An attempt to turn whois into a distributed directory of every person and service on the internet.
- Wi-FiWireless networking per the IEEE 802.11 standards.
- Wi-Fi 6 (802.11ax)The Wi-Fi generation that optimised for many simultaneous clients rather than peak speed for one.
- Wi-Fi 7 (IEEE 802.11be)The newest Wi-Fi generation — up to ~46 Gbps theoretical, Multi-Link Operation, 320 MHz channels.
- Wi-Fi meshA system with multiple router nodes that together cover the home — one SSID, automatic roaming between nodes.
- WIAMicrosoft's driver API that let Windows talk to scanners and digital cameras without every program writing its own hardware…
- Wide trail strategyA block cipher design method that proves a lower bound on the number of active S-boxes, making differential and linear…
- Wide-block cipherA block cipher that encrypts a whole block, such as a disk sector, so that flipping one bit changes everything in that block.
- Wide-format printerPrinters for paper roughly 60 cm wide and up — posters, drawings, banners and signs — that took over where pen plotters left…
- Widget Creation Library (Wcl)A library that let the entire interface of an Xt program be described in an ordinary X resource file, with no compiler and…
- Widget toolkitThe library of ready-made buttons, menus, scrollbars and text fields, plus the event loop and layout rules that hold them…
- Wiener's attackA cryptanalytic attack that recovers an RSA private key when the private exponent is too small, using continued fractions.
- Wietse VenemaThe Dutchman who wrote the security tools every Unix admin ran without ever wondering who made them.
- WikidataWikimedia's free knowledge graph — Wikipedia's facts as structured, machine-readable data.
- Wikimedia FoundationThe San Francisco nonprofit that runs Wikipedia and its sister projects, and pays for the servers with fundraising banners.
- WikipediaThe free encyclopedia anyone can edit — which against all odds turned out good.
- Wild compoA demoparty's catch-all competition for anything that doesn't fit any other category.
- Wildcat!Commercial BBS software from California, aimed at businesses as much as at hobbyist sysops.
- Wilhelm SchickardThe Tübingen professor who built Kepler a calculating machine twenty years before Pascal, and whose only copy burned before…
- Will Schroeder (harmj0y)The red teamer who taught a generation of attackers to see Active Directory as a graph.
- will-changeA CSS property that hints to the browser in advance that an element will soon be animated or changed, so it can prepare an…
- Willgodt OdhnerThe Swedish engineer whose pinwheel became the most-copied calculating mechanism in the world.
- William BinneyThe NSA mathematician who built a surveillance system with privacy protection baked in, then watched the agency pick one…
- William FriedmanThe geneticist who became America's leading codebreaker and gave the field both its statistical toolkit and the word…
- William OughtredAn English clergyman who set two logarithmic scales side by side and let them slide — inventing the slide rule around 1622.
- William ShockleyLed the transistor group, invented the sturdy junction transistor — and seeded both Silicon Valley and his own disgrace.
- Williams tubeThe first memory with genuine random access: bits stored as spots of charge on the inside of an ordinary television tube.
- Willis WareThe RAND engineer whose 1970 report is usually treated as the birth certificate of computer security.
- Wim van EckThe Dutch engineer who showed in 1985 that a computer screen could be read from a distance with a modified TV set.
- WIMPWindows, icons, menus, pointer — the four ingredients of nearly every desktop interface since 1980.
- WinbondTaiwanese memory maker whose eight-pin flash chips sit on almost every motherboard.
- Winchester driveThe design that made the hard disk sealed, cheap and reliable — and that every drive since has been built on.
- Wind RiverThe company behind VxWorks, the real-time operating system quietly running inside space probes, aircraft, routers and…
- Winding orderThe order — clockwise or counter-clockwise — in which a triangle's vertices are listed, which decides the side the renderer…
- WindowRectangular UI region owned by an application. Born at Xerox PARC ~1973 with Smalltalk-72. Macintosh (1984) made windows…
- Window attributes (X11)The fifteen per-window settings the X server keeps — background, border, event mask, cursor, colormap and a few more — which…
- Window border (X11)The frame the X server can draw around every window by itself, outside the window's area — a feature of the 1980s protocol…
- Window functionA SQL function that computes a value over a set of rows ("window") related to the current row, without collapsing them the…
- Window MakerAn X11 window manager that imitates NeXTSTEP so faithfully it still looks like 1989.
- Window managerThe program that decides where windows go, which one has focus and what the frame around them looks like.
- Window menuThe menu behind the leftmost button in the title bar, with Restore, Move, Size, Minimize, Maximize and Close, present in…
- Window placementThe window manager's rule for where a new window lands when the program has said nothing — by hand, at random, in a cascade…
- Window shadingRolling a window up so that only its title bar remains, like a blind, instead of minimising it.
- Window SnyderSecurity executive with Microsoft, Mozilla, Apple and Intel on her CV — and a first name nobody forgets in an…
- Window systemThe layer that shares one screen, keyboard and mouse among several programs by giving each a rectangle to draw in and…
- WindowLabNick Gravgaard's 2001 window manager with a few ideas of its own: clicking focuses a window without raising it, the taskbar…
- WindowsMicrosoft's operating system and still the desktop's dominant player at roughly 70% share.
- Windows 1.0Microsoft's first graphical environment, where windows sat side by side and were never allowed to overlap.
- Windows 2.0The December 1987 release in which windows were finally allowed to overlap, Excel got a home and Apple got a reason to sue.
- Windows 3.xVersions 3.0 from 1990 and 3.1 from 1992 turned Windows into the desktop environment the PC world actually used, after five…
- Windows 95The launch that had people queuing at midnight to buy an operating system — and that gave the world the Start button.
- Windows NTThe serious Windows line, built from scratch by the architect of VMS — and the code every Windows since XP rests on.
- WindsurfAI-first code editor from Codeium (rebranded to Windsurf in 2024). A Cursor competitor with a "Cascade" agent that runs…
- Winged-edgeA classic polygon-mesh data structure in which each edge remembers its two vertices, its two adjacent faces and its four…
- winget (Windows Package Manager)Microsoft's official Windows package manager — preinstalled on Windows 11. winget install Mozilla.Firefox.
- WINGsWindow Maker's own widget toolkit, "WINGs Is Not GNUstep": a small C library that draws NeXT-grey buttons and dialogs…
- Winn SchwartauAmerican writer who warned Congress about an "electronic Pearl Harbor" in 1991 and then wrote the book on information…
- WINTERPA Lisp interpreter with Motif built in, letting you rebuild an interface while the program was still running.
- WinUAEThe most accurate Amiga emulator — cycle-exact enough to run the demoscene's hardware-tuned productions that assume perfect…
- WiproAn Indian cooking-oil maker that became one of the world's largest IT services firms and kept the sunflower in its logo.
- WireGuardModern, minimalist VPN implementation — faster, more secure and simpler than OpenVPN/IPsec.
- WireGuard roamingWireGuard's ability to seamlessly follow along when a client changes network/IP (WiFi → cellular). The server identifies…
- WiresharkThe dominant open-source packet analyzer. Gerald Combs, 1998 (then called Ethereal). Can dissect 3000+ protocols, visually…
- WiseCross-border money transfer that built an entire business on showing the exchange rate banks would rather hide.
- WishThe original "ultra-cheap Chinese trinkets" app — peaked in 2018 then crashed against Temu/Shein. Sold to Qoo10 in 2024 for…
- WistronAcer's old factories, cut loose so that Acer's rivals would dare to place orders.
- WixIsraeli drag-and-drop website builder for non-developers — 200M+ users. Wix ADI (AI-generated website) in 2016 was an early…
- WizThe cloud security company that reads a customer's entire cloud estate through APIs instead of installing agents, and ended…
- Wizard (MUD)The player who has climbed all the way to the top and thereby stopped playing — and now runs and builds the world instead.
- wlrootsThe library that made writing a Wayland compositor a thousand-line job instead of a sixty-thousand-line one — built for Sway…
- wm (Andrew)The window manager of Carnegie Mellon's Andrew system, written in 1983 by James Gosling and David Rosenthal: tiled…
- WM_CLASSThe ICCCM property carrying a program's instance and class names, which the resource database and window managers use to…
- WM_CLIENT_LEADERThe ICCCM property that points at a program's leader window, the only one carrying the session ID, so a session manager…
- WM_CLIENT_MACHINEThe ICCCM property naming the machine an X program runs on — meant so rsh would know where to restart it, today mostly the…
- WM_COLORMAP_WINDOWSThe ICCCM property in which a program lists which of its subwindows carry their own colormaps, so the window manager knows…
- WM_COMMANDThe ICCCM property holding the command line a program was started with, meant for restarting it after logout, and still a…
- WM_DELETE_WINDOWThe ICCCM protocol that makes the close button ask the program instead of shooting it.
- WM_HINTSThe ICCCM property carrying an X client's small requests to the window manager: whether it wants keyboard focus, whether it…
- WM_ICON_SIZEThe ICCCM property on the root window where the window manager says which icon sizes it would like — one of the rare cases…
- WM_NAMEThe ICCCM property that carries an X window's title: the text the window manager paints in the title bar, and which any…
- WM_NORMAL_HINTSThe ICCCM property through which an X program tells the window manager how big it wants to be: minimum and maximum size…
- WM_PROTOCOLSThe ICCCM property where an X client lists which conversations it is willing to have with the window manager — close, focus…
- WM_SAVE_YOURSELFICCCM's first attempt at session management: the window manager asks a program to write down how to restart it, and the…
- WM_SnICCCM 2.0's selection, one per screen, that a window manager takes ownership of when it starts — so another can take over…
- WM_STATEThe property a window manager sets on a client window to say which state it is in — and which, in practice, became the…
- WM_TAKE_FOCUSThe ICCCM protocol that, together with one flag in WM_HINTS, gives four different answers to who decides where keyboard…
- WM_TRANSIENT_FORThe ICCCM property that names which main window a dialog belongs to, so the window manager can keep it on top and hide it…
- WM_WINDOW_ROLEThe ICCCM property holding a short name for which of a program's windows a window is — "browser", "3pane", "gimp-toolbox"…
- wm2A minimalist 1990s window manager, instantly recognisable by the window title sitting on a tab down the side instead of…
- wmctrlThe command-line tool that drives any EWMH-compliant window manager — list windows, activate one, maximise, switch desktop…
- wmiiA tiling window manager controlled through a filesystem, in the spirit of Plan 9.
- wmxChris Cannam's follow-up to wm2: the same sideways title tab and shaped frames, plus "channels" for multiple desktops, a…
- Wobble grooveThe guide groove on a blank recordable disc weaves slightly side to side, giving the drive a clock and an address on media…
- WobblerAn effect that distorts an image or raster line with a running sine table so that it appears to wobble like rubber.
- Wobbly windowsThe 2006 Compiz effect that made windows wobble like jelly when dragged, and did more than anything else to get people…
- WojakThe crudely drawn bald figure used to express an emotional state. Unlike Pepe he isn't a character but a template.
- Wolfram ResearchStephen Wolfram's privately held company behind Mathematica, Wolfram|Alpha and a programming language named after its…
- WolfspeedAmerican chipmaker, formerly Cree, that bet the whole company on silicon carbide instead of ordinary silicon.
- WordNative data size for a CPU architecture — the number of bits the CPU processes at once in its registers. 64 bits on modern…
- Word clockA shared timing signal that makes several digital audio devices take their samples at exactly the same moment.
- Word sizeThe natural data width a processor works with — how many bits its registers, ALU, and pointers typically handle in one go…
- Word2VecClassic word embedding model from Google (2013) — showed that words can be represented as vectors with meaning.
- WordPerfect CorporationThe Utah company behind the word processor that owned the DOS era and then missed Windows.
- WordPressThe world's most-used CMS — powers ~40% of all websites. PHP + MySQL, open source, plugin ecosystem.
- Work factorThe amount of computation a password hashing function should cost per guess, tuned upward as hardware gets faster.
- work_memHow much memory a single sort or hash table may use before spilling to disk. The most misunderstood setting in PostgreSQL.
- WorkbenchThe Amiga's graphical desktop — and, in everyday speech, the whole of AmigaOS.
- WorkdayThe cloud HR and finance system that PeopleSoft's founder built as payback after Oracle's hostile takeover.
- Workload IdentityCloud feature where a workload (pod, lambda, container) gets cloud-resource access without long-lived credentials. The…
- WorkOSAn API that gives SaaS products the enterprise features big customers demand — SSO, SCIM and directory sync — without…
- Workplace ShellOS/2's object-oriented desktop from 1992, where files, printers and folders were objects with inheritance — and where one…
- Workspace ManagerNeXTSTEP's file manager and desktop shell, the program that owned the dock, the shelf and the column view that the Finder…
- World of WarcraftThe MMO that took the genre mainstream, with twelve million paying players at its peak.
- World PartitionSplits an open game world into a grid that streams in and out automatically around the camera, replacing hand-authored level…
- World spaceThe shared coordinate system in which every object in a scene is placed relative to the others.
- World Wide Web (WWW)The hypertext system layered on the internet — three inventions in one: URL, HTTP and HTML.
- WorldComThe telecom giant that bought a large chunk of the internet's backbone and then filed what was, at the time, the largest…
- WorldpayCard acquirer born in 1997 British web retail, and one of the most frequently resold companies in payments.
- Worley noiseCellular noise, introduced by Steven Worley in 1996, that colours each point by its distance to the nearest scattered…
- WORMStorage where data can be written once but never altered or erased — immutability as a physical property, not a permission.
- WormSelf-replicating malware that spreads over the network without any user action.
- Wouter CastryckBelgian mathematician at KU Leuven who, with Thomas Decru, broke SIKE on a laptop in 2022 – one of the most dramatic moments…
- Wow and flutterPitch wobble caused by tape or a record not moving at a perfectly steady speed.
- WP EngineThe managed-WordPress giant that went to open war with WordPress's own founder in 2024.
- WPA (Wi-Fi Protected Access)The security standard for Wi-Fi — encrypts traffic between device and access point.
- WPA Enterprise (WPA2/WPA3-Enterprise)"Corporate Wi-Fi" — every user logs in with username/password or cert instead of a shared PSK. Built on 802.1X + RADIUS +…
- WPA3The third generation of Wi-Fi security — replaces WPA2's weak 4-way handshake with SAE (Simultaneous Authentication of…
- WPA3-EnterpriseWPA3 mode for enterprise WiFi. 192-bit security suite (GCMP-256, ECDHE-384). Mandatory CNSA compliance for US-DoD…
- WPS (Wi-Fi Protected Setup)The feature meant to make joining a wireless network easy without typing the password. Launched in 2006 by the Wi-Fi…
- WrapperCode layer that wraps existing functionality to alter the API — simplify, adapt, add tracing/caching, bridge between…
- WREDWeighted Random Early Detection — congestion avoidance in routers. Drops packets probabilistically BEFORE queue is full…
- write (Unix)Unix's oldest way to talk to another user: type lines, and they appear in the middle of their terminal.
- Write amplificationThe ratio between logical writes (what the application asks for) and physical writes (what actually hits disk). SSD…
- Write amplification (DB)When a single logical write to the database causes several physical writes to disk. A central problem in LSM-tree-based…
- Write cacheBuffer in disk/controller that accepts writes to RAM before they reach permanent media. Massive performance gain but risk…
- Write precompensationDeliberately writing some flux transitions early or late to counter neighbouring bits shoving each other on the crowded…
- Write skewConcurrency anomaly: two transactions both read overlapping data, both update based on what they saw, end-state is invalid…
- Write spliceThe magnetic seam that forms where a new write session meets previously written content on tape.
- Write stallWhen an LSM-based database deliberately slows or fully stops incoming writes because compaction cannot keep up. The…
- Write-backCache policy: writes land only in cache, flushed later to the underlying media. Faster than write-through but risk: cache…
- Write-back cacheA caching strategy where a write only goes to the cache immediately and is written through to the slower layer later (when…
- Write-protect notchA notch or sliding tab on a floppy's edge that physically tells the drive it may not write.
- Write-throughCache policy: every write goes to both cache and underlying media at the same time. Read-cache benefit retained; write…
- Write-through cacheA caching strategy where every write goes both to the cache and to the backing layer immediately. Safer than write-back (no…
- WriteFreelyA minimalist, self-hosted blogging platform focused purely on writing — no widgets, no analytics obsession, no distraction…
- Wrong-key randomization hypothesisThe assumption that decrypting with a wrong key guess produces random-looking statistics, so the right key stands out.
- WSDL (Web Services Description Language)XML format for describing SOAP web services. W3C Recommendation 2007. Defines operations, port types, bindings, messages…
- WSL (Windows Subsystem for Linux)Microsoft's way of running Linux binaries on Windows. WSL1 (2016) translated Linux syscalls. WSL2 (2019) runs a real Linux…
- WSLgMicrosoft's own bridge that lets graphical Linux programs in WSL 2 open windows on the Windows desktop, built on Weston…
- wu-ftpdThe FTP server built to keep wuarchive from collapsing, which then shipped with half the Unix world.
- wuarchiveWashington University in St. Louis's FTP archive, one of the biggest places on the early-90s net to fetch software from.
- WwiseAudio middleware from Canada's Audiokinetic that lets sound designers build game audio without queueing for a programmer.
- WWIVBBS software whose released source code turned it into a platform for hundreds of home-built variants.
- WWIVnetThe BBS network that linked WWIV boards for mail and discussion groups, alongside the larger FidoNet.
- wxWidgetsThe cross-platform C++ framework from 1992 that, instead of drawing its own buttons, wraps the native controls of Windows…
- WYSIWYGWhat You See Is What You Get — the editor shows the document as it will look, not as marked-up code.
X
- DOM-based XSSXSS variant where exploit never touches server — vulnerable JavaScript on client reads user input (URL hash, location…
- Reflected XSSXSS variant where malicious payload is included in URL/request and "reflected" back in server response without persistence…
- Stored XSSXSS variant where malicious script is stored permanently on server (DB, filesystem) and served to all subsequent visitors…
- X (demoparty)A Dutch demoparty where the Commodore 64 is the only machine that counts.
- X ConsortiumThe vendor club that looked after X11 from 1988 to 1996 and lent the MIT License one of its names.
- X extensionThe mechanism that has let X11 grow new capabilities for nearly forty years without the core protocol changing once.
- X font server (xfs)A separate service that handed out fonts to X servers over the network, from an era when fonts were something the server…
- X selections (PRIMARY and CLIPBOARD)How X11 moves text between programs: two parallel clipboards and an agreement that the data only exists while the sender is…
- X terminalA display with a built-in X server and nothing else: the programs ran on a Unix box in the machine room.
- X Toolkit Intrinsics (Xt)The framework that gave C programs under X11 widgets, inheritance and callbacks — and no look whatsoever.
- X-CopyThe Amiga's dominant disk-copying program — with the Cyclone add-on it could nibble-copy even protected disks.
- X-DesignerThe British Motif builder that Sun sold as its own, and which in its final act tried to rescue its customers from Motif by…
- X-FaceA mail and Usenet header that carried a tiny black-and-white picture of the sender, encoded as a few hundred characters of…
- X-No-ArchiveThe header line X-No-Archive: yes, which asked Usenet archives to forget a post — and worked right up until someone quoted…
- X-Resource (X11 extension)The extension that lets a client ask the server how much room the other clients are taking: how many windows, pixmaps and…
- X.25The telcos' packet network before the internet — slow, expensive, and so meticulous about error correction that it worked…
- X.400The telcos' and standards bodies' email, meant to replace the internet's SMTP and beaten by it instead.
- X.500The OSI world's global phone book for the network — never finished, but with descendants in almost every corporate network.
- X.509ITU-T standard for public-key certificates — the structure every TLS, code-signing and S/MIME certificate follows.
- X.desktopIXI's file manager and desktop for X11 from 1988, the first commercial attempt to give Unix icons and a wastebasket, and the…
- X.Org FoundationThe non-profit that has stewarded the X Window System since 2004, whose real innovation was letting individual developers in…
- X.Org ServerThe reference implementation of X11 since 2004, and the X server behind almost every Linux desktop for two decades.
- X10The first version of X to escape MIT, and the one that taught everyone why the next version had to start over.
- X11 (X Window System)The classic display system for Unix. MIT, 1984. Version 11 (1987) is still current. Network-transparent (you can run X apps…
- X11 forwardingRunning a graphical program on a remote machine and getting its window on your own screen, tunnelled through SSH.
- X11/NeWSSun's attempt to avoid choosing: one window server that spoke both X11 and NeWS in the same process, kept alive until 1993.
- x11perfThe benchmark shipped with X that measures how many times per second a server can perform a given drawing operation.
- X11R1The first release of X version 11, September 1987, carrying the protocol that has not changed since and a server written at…
- X11R2The first X release from the MIT X Consortium, in 1988 — less a new version than proof that the R1 protocol actually held up.
- X11R3The October 1988 X release in which the Xt toolkit took the shape that Motif and Athena went on to build on.
- X11R4The December 1989 release that gave X11 its rulebook: ICCCM, XDMCP, the Shape extension, cookie-based access control and twm…
- X11R5The September 1991 release that taught X11 languages other than English, measurable colour, scalable fonts served from a…
- X11R6The sixth and final major release of X11, shipped in 1994, whose name outlived its contents by a decade thanks to the…
- X11R7The December 2005 release in which X.Org sawed the monolithic source tree into hundreds of modules, swapped imake for…
- x11vncThe VNC server that shares the X display already running, rather than creating a new invisible one, so the remote user sees…
- X2GoRemote desktop for Linux built on the free NX code, with everything tunnelled through SSH and sessions you can disconnect…
- X386The first free X server for ordinary PCs, written by Thomas Roell in 1991, and the root of XFree86 and therefore of the…
- x86 (x86-64 / AMD64)The classic CPU architecture from Intel — has dominated PC and server datacenters since the 80s.
- X9.63 KDFThe key derivation function from the ANSI elliptic-curve standard: hash the shared secret, a counter and some context…
- XAAXFree86's first shared layer for 2D acceleration: the driver filled in a table of what the card could do, and XAA handled…
- XACE (X Access Control Extension)The X server's internal access-control hooks, modelled on LSM in the Linux kernel: a security module gets to say yes or no…
- xAIElon Musk's AI company, founded in July 2023 with the stated goal of "understanding the true nature of the universe". Builds…
- XamarinThe framework that let C# developers build native mobile apps — bought by Microsoft in 2016 and retired in favour of .NET…
- XangaBlogging platform from 1999 which, together with LiveJournal, constituted teenage diary-writing online before social media…
- XAudio2Microsoft's game audio API for Windows and Xbox, the successor to DirectSound once hardware mixing had gone away.
- XauthX11's way of deciding who may draw on a display: a secret cookie in a file, sent in plain text.
- xautolockA small program that locks nothing itself; it watches how long keyboard and mouse have been idle and launches a screen…
- Xaw3dAthena widgets with bevelled edges: an early-1990s library that gave X's free software a Motif-like 3D look without changing…
- xbiffA tiny mailbox in a window whose flag pops up when new mail has arrived: the X world's first notification icon.
- XBinA file format that bundles textmode art's screen data, custom font and palette into one file, so the art renders correctly…
- xbindkeysThe older, window-manager-agnostic way of binding keys and mouse buttons to shell commands on X11.
- XBMX's format for monochrome bitmaps, stored as C source code that can be included straight into a program.
- xBRA rule-based pixel-art scaler that works out which way an edge runs and rounds it off without smearing the rest of the image.
- XC-APPGROUPThe extension meant to let one X program embed others inside itself, acting as their window manager.
- XC-MISCThe small X11R6 extension that lets a client ask the server which resource IDs have become free again, so that a program…
- xcalcThe X11 calculator, which imitates a Texas Instruments TI-30, or with -rpn an HP-10C with reverse Polish notation.
- xcapeThe X11 tool that makes a modifier key do something else when tapped on its own — most often turning Control into Escape.
- XCBA thin, asynchronous C library for the X protocol that took over from Xlib as the layer everything else sits on.
- XCBC-MACThe patch that made CBC-MAC safe for messages of any length, at the cost of carrying three keys around.
- XChaCha20A ChaCha20 variant with a 192-bit nonce, large enough to pick at random for every message without worrying about collisions.
- xclip and xselThe two small programs that connect shell pipes to X selections, so that cmd | xclip becomes a clipboard entry and xsel -b…
- xclipboardThe X distribution's own clipboard program: a small Athena window that takes over the CLIPBOARD selection and keeps what was…
- xclockAn analogue clock in a window, used for three decades mainly to check whether X works at all.
- XcmsThe colour management system in X11R5 that let a program ask for a colour in CIE coordinates and get something that looked…
- XcodeApple's official IDE. Mac-exclusive. The only officially supported way to build apps for…
- xcompmgrThe sample compositor that proved the Composite extension worked — drop shadows on Linux in a couple of thousand lines of C.
- xconsoleA window that catches what would otherwise be written to /dev/console, so the kernel's and syslog's shouting does not land…
- XcursorThe library that gave X11 mouse pointers in colour, with shadows and animation, loaded from themes on disk instead of from a…
- xcutselA small X program with two buttons that shuttle text between the PRIMARY selection and the old cut buffer, for programs that…
- xdaliclockJamie Zawinski's X11 clock whose digits melt into one another as the time changes, a nod to Dalí with roots on the Xerox…
- XDarwinThe volunteer project that got XFree86 running on Mac OS X in the years before Apple had an X11 of its own — and that…
- XDCCIRC file bots that hand out numbered packs over DCC on request.
- XDF (Extended Density Format)IBM's early-1990s format that squeezed 1.86 MB onto an ordinary 3.5-inch HD floppy by using sectors of different sizes.
- XDG Base DirectoryThe specification that tries to get programs to keep configuration in ~/.config, data in ~/.local/share and cache in…
- xdg-shellThe Wayland protocol that turns a surface into an actual window — title, maximize, fullscreen, size negotiation, popup menus…
- XDMThe X Display Manager: the grey login box that started X sessions locally and served X terminals over the network.
- XDMCPThe protocol that let an X server with no computer of its own ask a display manager across the network for a login box, on…
- XdmxThe proxy X server that stitched screens on several computers into a single desktop — Xinerama over the network.
- XDNDThe protocol that finally let applications from different toolkits drag and drop things onto each other under X11.
- xdotoolThe command-line tool that impersonates the user: it presses keys, moves the mouse, and finds, focuses and moves X11 windows…
- XDP (eXpress Data Path)A hook in the Linux kernel that runs an eBPF program on a packet as early as possible — in the driver, before the kernel has…
- xdpyinfoDumps everything an X server will say about itself: version, vendor, extensions, screens, depths and visuals.
- XDRExtended Detection and Response — an evolution of EDR that correlates signals from several sources (endpoints, network…
- xearthDrew the Earth as your desktop background, with day and night exactly where they were at that moment.
- xeditThe X distribution's own text editor, meant as a demonstration of the Athena text widget, which under XFree86 acquired a…
- XEmbedA protocol for embedding one X program's window inside another's so the two behave like a single surface.
- XenA type 1 hypervisor out of the Cambridge University Computer Laboratory, published in 2003. It built the entire first…
- XenixMicrosoft's own Unix — and for a few years in the mid-1980s the most widely installed Unix variant in the world.
- Xeno KovahFirmware researcher who thought low-level security should be learnable without first working for an intelligence agency…
- XenSourceThe startup meant to commercialise the Xen hypervisor, which became Citrix's answer to VMware instead.
- XeonIntel's server CPU since 1998 — for a long time synonymous with "server CPU", has lost ground to EPYC.
- XephyrAn X server that runs inside a window on another X server: a desktop within the desktop.
- XerographyThe dry electrophotographic copying process where light, static charge and toner powder draw the image — the heart of both…
- XeroxThe American document giant that invented the modern photocopier — and then, through its research lab, nearly the entire…
- Xerox 914The first automatic plain-paper copier — the machine that turned Haloid into Xerox and "to xerox" into a verb.
- Xerox 9700Xerox's first laser printer on the market, 1977 — 120 pages a minute at 300 dpi, and the beginning of the end for preprinted…
- Xerox AltoThe computer that had windows, a mouse, Ethernet and word processing in 1973 — and that Xerox never sold to anyone.
- Xerox PARCInvented the personal computer as we know it — and became the textbook case of a company that failed to understand what its…
- Xerox StarThe first commercial computer with icons, folders and a wastebasket — and one of the industry's most instructive commercial…
- Xerox ViewPointThe 1985 rewrite of the Star software that made the Xerox desktop modular and far cheaper, and which, renamed GlobalView…
- XeSSIntel's AI-based temporal upscaler that renders at low resolution and reconstructs a sharper image — Intel's answer to DLSS…
- xevA tiny X program that opens a window and prints every event that reaches it — the right tool when a key isn't doing what it…
- XEvIEThe X extension that let a single program intercept, modify or discard every key and mouse event before it reached its…
- XEX modeA block cipher mode that XORs input and output with a mask that depends on the block's position.
- xeyesA pair of eyes that follow the mouse pointer — X's best-known demo and an unexpectedly useful diagnostic.
- xf86-input-evdevThe X server's generic driver for the Linux kernel's evdev interface, and the reason a USB mouse could be plugged in without…
- xf86-input-synapticsThe X touchpad driver with a hundred or so options, each of which some laptop owner considered indispensable.
- xf86-video-vesaX's last resort on a PC: a driver that knows nothing about the graphics card, asks the BIOS for a video mode and draws…
- XF86VidModeThe XFree86 extension that let programs and key combinations switch video modes while X was running, the one 1990s games…
- XfceA lightweight desktop that started life as a free CDE lookalike and became the default answer for machines that can't cope…
- xfdThe X font displayer: a window with a grid showing every character in a font, 256 at a time.
- XFIXESThe X extension that swept up the odds and ends the core protocol forgot, and that modern compositors can't live without.
- xfmThe 1990s file manager for X built on Athena widgets, with one window for files and one for programs, so that people without…
- xfontselA clickable form over the fourteen fields of an XLFD name, for finding a font among the X server's core fonts without typing…
- XForms (toolkit)A compact widget toolkit for X written straight against Xlib in the 1990s, best known because LyX and the very first Xfce…
- XFree86The free X server for PCs that gave Linux and BSD a graphical desktop throughout the 1990s, then lost everything over a…
- XFree86-BigfontThe XFree86 extension that stopped shipping hundreds of kilobytes of glyph metrics down the wire every time a program opened…
- XFSHigh-performance journaling filesystem. SGI 1994 (for IRIX). Port to Linux 2001. Default on RHEL 7+ desktop + server…
- xfsttThe small font server that gave X11 TrueType in the late 1990s, and thereby let Linux users borrow Arial and Times New Roman…
- XftThe library that moved fonts from the X server into applications, and with that gave the Linux desktop anti-aliased text.
- xfwm4Xfce's window manager since version 4, one of the first with a built-in compositor and one of the last that insists on…
- XGBoostLibrary for gradient boosting of decision trees, released in 2014 by Tianqi Chen. It dominated Kaggle to the point where…
- xgcThe X graphics demo — a panel with a button for every setting in a graphics context and a pane where you can see what they…
- XglNovell's X server that drew everything through OpenGL and made Compiz possible in 2006, before Red Hat's AIGLX made it…
- XGS-PON10-Gigabit-capable Symmetric PON — the successor to GPON, with 10 Gbit/s symmetric (as much up as down). Rolling out to…
- xhostThe X server's original access control, which admits whole machines — and whose best-known invocation switches control off…
- XHTMLHTML reformulated as XML — strict syntax, every tag must close, attributes quoted. W3C's chosen path ~2000. Today…
- XiaomiChinese manufacturer that started with an Android fork, moved on to cheap phones and now sells more or less anything that…
- Xiaoyun WangThe cryptanalyst who broke the collision resistance of MD5 and SHA-1 in 2004–05, sending half the world's hash functions…
- XID wraparoundPostgreSQL transaction IDs are 32 bits and wrap around. Fail to retire the old ones in time and the database stops accepting…
- XIE (X Image Extension)Image processing inside the X server: a fix for 1990s document imaging that almost nobody else needed.
- XilinxInventor of the FPGA — the chip you can rewire after it leaves the factory.
- XIM (X Input Method)X11's framework for typing languages with more characters than the keyboard has keys.
- XImageXlib's structure for an image living in the client's memory, as opposed to a pixmap living in the server, and the road every…
- XimianHelix Code, later Ximian: the company that tried from 1999 to 2003 to turn GNOME into a product, and created Evolution, Red…
- XineramaThe X11 extension that merged several monitors into one big surface, so windows could finally be dragged from one to the…
- xinit and startxThe bare-bones way to start X from a text console: one server, one script, and a session that lives exactly as long as the…
- XInputThe X11 extension that taught a system built for one mouse and one keyboard about tablets, touchscreens and more than one…
- XircomThe company behind the network and modem cards poking out the side of every road warrior's laptop.
- XKBThe X Keyboard Extension, a keyboard-layout system that outlived the window system it was built for.
- xkbcompThe compiler that turns XKB's text descriptions of keyboards into something the X server can load — and which the server…
- xkbprintThe X.Org utility that draws the current keyboard as PostScript, with each key's symbols printed in the right place.
- xkeyboard-configThe database of the world's keyboard layouts that XKB reads, and that both X and Wayland now depend on.
- xkeycapsJamie Zawinski's graphical front end to xmodmap: a picture of the keyboard on screen, click a key and see or change what it…
- xkillThe X11 utility that turns the pointer into a skull and evicts whichever program owns the window you click.
- XLFDX's old naming scheme for fonts: fourteen hyphen-separated fields, for anyone who finds "Courier 12" too readable.
- XlibThe C library that turns function calls into X protocol messages, and that hardly anyone calls directly any more.
- Xlib error handlingWhy an X program can die from an error in a request it sent twenty calls ago, and what XSetErrorHandler and -sync do about…
- xloadA scrolling bar chart of the system load average, refreshed every ten seconds since the days of X10.
- xlockThe classic X screen locker, which hid the terminal behind an animated pattern and lived on for decades as xlockmore.
- xlogoA program that does nothing but display the X Window System logo, which is precisely why it became the standard test for…
- XLR connectorThe round, latching connector that carries nearly every microphone signal on a stage or in a studio.
- xlsatomsLists every atom the X server knows, from the predefined PRIMARY at number 1 to the thousands of names today's clients have…
- xlsclientsThe command that lists which programs are running against an X display, machine by machine and command line by command line…
- xlsfontsThe command-line tool that asks the X server which core fonts it has and prints their full XLFD names, one per line.
- XM (Extended Module)FastTracker 2's module format, which extended MOD with envelopes, 16-bit samples and thirty-two channels.
- xmagThe X Window System's magnifying glass: pick a patch of screen and see it blown up in a window of its own, pixel by pixel.
- xmanA graphical man page browser built on Athena widgets, descended from an X10 version Barry Shein wrote in the 1980s.
- XmArrowButtonA Motif button with no label, just a bevelled triangle pointing one of four ways.
- XmBulletinBoardThe simplest of Motif's manager widgets, placing children exactly where their x and y say, and, as the base class of XmForm…
- XmCascadeButtonThe entry in a Motif menu bar that drops down a menu — or, inside a menu, opens a submenu marked with a small arrow.
- XmComboBoxThe combo box Motif only got in version 2.0 in 1994: a text field and a list in one widget.
- XmContainerMotif 2.0's answer to the file manager window: one widget that shows icons laid out freely, as a tree, or as a table.
- XmDialogShellThe top-level window wrapped around every Motif dialog, which programmers rarely create by hand.
- XmDrawingAreaMotif's blank widget: a surface with no look of its own that merely reports when it needs repainting, has been resized or…
- xmessageA window with some text and a row of buttons, the X equivalent of echo, meant for shell scripts that need to ask the user…
- XmFileSelectionBoxMotif's file dialog: one filter, two lists and four buttons, unloved enough that Netscape users on Unix learned to type the…
- XmFormMotif's layout widget, where every child is anchored to edges, neighbours or percentage positions rather than given…
- XmFrameA Motif container for exactly one child, whose only job is to draw a shadowed border around it.
- xmhAn X front end on top of the MH mail system, where each button in the window corresponds to an MH command run in the…
- XmingA small, free X server for Windows that became PuTTY's standard companion for anyone wanting to run Unix programs…
- XML (Extensible Markup Language)Structured data format from 1998 — predecessor to JSON but still in use for SOAP, RSS, Office documents.
- XML Schema (XSD)W3C standard (2001) for describing the structure and types of XML documents. Itself an XML dialect. Replaced the simpler DTD…
- XmLabelMotif's simplest widget, a piece of text or a picture that does nothing at all, and the ancestor of nearly every button in…
- XMLHttpRequest (XHR)Original browser API for AJAX. Microsoft, Outlook Web Access, 1999. Standardized by W3C ~2006. Drove the entire AJAX…
- XmListMotif's list widget: rows of XmString with four selection models, from one row at a time to Shift- and Ctrl-click, and…
- XmMainWindowMotif's frame for an application's main window: menu bar on top, work area in the middle, optional command and message…
- XmManagerMotif's abstract base class for widgets that hold other widgets, and the thing that quietly makes gadgets work.
- XmMenuShellThe invisible Motif shell that every pulldown and popup menu lives in, letting the menu sit on top of everything without the…
- XmMessageBoxMotif's standard dialog with a symbol, a message and the OK, Cancel and Help buttons, which in five disguises gave 1990s…
- XmNotebookMotif 2.0's tab widget from 1994, drawn as a binder with a spiral spine and shaded page edges, which arrived just in time…
- xmobarA text-based status bar written in Haskell, effectively the default panel for xmonad users.
- XMODEMOne of the first file-transfer protocols for modems, built by Ward Christensen in 1977 and nearly impossible to avoid on the…
- xmodmapThe command-line tool that edits the X server's keycode-to-symbol table, and with it what each key actually does.
- xmonadA tiling window manager written in Haskell, whose config file is itself a Haskell program recompiled on every change.
- xmoveA 1994 X proxy that did the impossible, moving a running program from one display to another, by remembering everything the…
- XMP (Extreme Memory Profile)A ready-made profile in the memory module with higher frequency, tighter timings and higher voltage than the standard. One…
- XMP profileExtreme Memory Profile — Intel's standard for RAM modules to advertise their fast timings/frequencies so you can enable them…
- XmPanedWindowMotif's container that stacks its children with draggable dividers between them.
- XMPlayA tiny Windows player from Un4seen Developments that became the tracker crowd's favourite because it played modules…
- XMPP (Jabber)Open federated chat protocol based on streaming XML (1999, Jabber → RFC 6120/6121/6122) — the first serious competitor to…
- XmPrimitiveMotif's abstract base class for every widget that has no children — the place where each button, list and text field gets…
- XmProtocols (Motif)Motif's layer over ICCCM's WM_PROTOCOLS, turning window-manager messages into ordinary callbacks — and the reason so many…
- XmPushButtonMotif's ordinary push button: a shadowed label that sinks in when clicked and fires a callback once the mouse button is…
- XmRowColumnMotif's general-purpose manager that lines its children up in rows or columns, and which, in disguise, is every menu bar…
- XmScaleMotif's slider: a handle on a track that picks an integer between two limits.
- XmScrollBarMotif's scroll bar: two arrows, a slider sized to the visible portion, and a callback for every way of poking it.
- XmScrolledWindowMotif's container that puts scrollbars around a child too big for the space it has been given.
- XmSelectionBoxMotif's generic pick-from-a-list dialog, and the parent of both the file dialog and the XmCommand prompt.
- XmSeparatorMotif's widget for drawing a line, nothing more — but with seven ways of drawing it.
- XmSpinBoxMotif 2.0's widget for stepping through a value with a pair of arrow buttons, one number or one word at a time.
- XmStringMotif's "compound string": an opaque text type in which every segment carries a tag selecting font and writing direction…
- XmTextMotif's text editor as a widget, with a single-line sibling called XmTextField, and the thing dtpad, every dialog's entry…
- XmToggleButtonMotif's on/off widget, which becomes a checkbox or a radio button depending on a single resource.
- XmuX11's junk-drawer library: a collection of small functions that fit neither Xlib nor Xt but that every tool ended up needing…
- XNAMicrosoft's C#/.NET game framework, the first to let hobbyists ship games on a console.
- xnekoThe cat that chases the mouse pointer around an X screen, falls asleep once it catches up and scratches at the edge when the…
- XnestAn X server that is itself an X client — it shows an entire desktop inside a window on another X server.
- XOR (Exclusive OR)Boolean operator: true if exactly one input is true. Symbol: ⊕, ^. Peculiar property: A ⊕ B ⊕ B = A — its own inverse.
- XOR cipherThe XOR cipher combines plaintext and key bit by bit, and is secure only when the key is as long as the message, random, and…
- XOR spriteAn object drawn by XORing it onto the background and erased by drawing it again in the same place.
- xorg.confThe X.Org server's configuration file, heir to XF86Config, which a generation of Linux users edited by hand until the server…
- XPathQuery language for navigating XML trees. W3C standard 1999. Syntax like //book[@year>2000]/title.
- XPBDExtended Position Based Dynamics — the addition that makes a spring's stiffness independent of how many iterations and…
- XPdeA 2002 Linux desktop environment that copied Windows XP pixel for pixel, Start button and blue taskbar included.
- XPenguinsTiny penguins that walk, climb and tumble along the edges of the windows on your desktop.
- XPilotA multiplayer gravity shooter played over the internet, written at the University of Tromsø and played on workstations…
- XPMX PixMap, an image format for colour icons that also happens to be valid C source code.
- xprThe second half of X's screenshot pipeline: it takes a file from xwd and turns it into something a printer understands.
- XpraThe tool that does for windows what GNU screen does for terminals: programs run on an invisible X server, appear wherever…
- XprintThe idea that a printer is just another X screen, tried for a decade and then quietly removed.
- xpropThe command that turns the mouse pointer into a crosshair and prints everything X knows about the window you click.
- XPSMicrosoft's XML-based document format from 2006, pitched as a PDF without Adobe — and Windows' new print format.
- XQuartzThe X server for macOS, born as Apple's own X11.app and a standalone project since 2012, when Apple stopped shipping it.
- XQuerySQL for XML — a full query language with loops, filters and sorting layered on top of XPath.
- xrdbThe tool that runs a resource file through the C preprocessor and stores the result inside the X server, so every program on…
- Xref (Usenet)The header that told you where a cross-posted article had landed on your own server, so you only had to read it once.
- xrefreshA program that makes the entire X display repaint itself by covering everything with a window and immediately removing it.
- XRenderThe extension that gave X11 an alpha channel, fifteen years after the protocol was designed for monochrome screens.
- XresourcesX11's shared settings database, where colours and fonts for every program lived in one text file full of wildcards.
- xrestopA top for the X server: it lists every connected client and how many windows, pixmaps and other objects it is holding in the…
- xrnOne of the first graphical newsreaders: Usenet in an X11 window, with buttons instead of single-letter commands.
- xroachCockroaches that scurry around the root window and hide under application windows; move one, and the ones left exposed rush…
- XrunCatch-all for audio buffer underruns and overruns: the software failed to fill or drain a buffer in time, and you hear it as…
- xscopeA protocol sniffer for X11: it sits as a proxy between client and server and prints every request, reply, event and error in…
- XScreenSaverJamie Zawinski's screensaver and screen locker for X11, with hundreds of small graphics demos and some very firm opinions…
- XsessionThe shell script a display manager runs after a successful login, which in turn starts the user's graphical session.
- xsetX11's command-line control panel: screensaver, power saving, key repeat, the bell and the font path.
- xsetrootA tiny X11 utility for setting the root window's background, cursor and name — which accidentally became the status bar for…
- XSETTINGSThe freedesktop protocol that lets X programs change theme, fonts and DPI while running, through one property everyone reads…
- XSL attackAn algebraic attack proposed in 2002 which, had it worked as claimed, would have threatened AES.
- XSLT"Extensible Stylesheet Language Transformations" — W3C standard 1999 for transforming XML into other XML, HTML or text. A…
- xsmX11R6's own session manager from 1994, the reference implementation of XSMP, which saved which programs were running and…
- XSMPX11's protocol for saving a desktop session and bringing it back with every program and window where you left it.
- xsnowSnow falling across the X desktop, settling on the top edges of windows and occasionally joined by Santa and his reindeer: a…
- XSS (Cross-Site Scripting)When an attacker sneaks JavaScript code into a site so other users end up running it.
- XSS types (Stored / Reflected / DOM)Three main variants of XSS — depending on where the malicious code is stored and triggered.
- xss-lockThe glue between the X server's screensaver, systemd-logind and whichever locker you prefer — so the screen is actually…
- XsunSun's own X server for Solaris, which replaced X11/NeWS in 1993 and was itself replaced by X.Org when Solaris 11 arrived.
- XTEAAn improved variant of the TEA block cipher, published in 1997 to fix a weakness in the original.
- xteddyA teddy bear on your desktop that does nothing at all, and does it very well.
- xtermThe stock terminal of X11 — older than X itself and still the yardstick every other terminal emulator gets measured against.
- XTESTThe X extension that lets a client inject keystrokes and mouse movement the server treats as real.
- xtransThe transport layer under X11 — the code that opens a Unix socket, TCP or something older on behalf of Xlib, the X server…
- XTranslateCoordinatesThe Xlib call that converts a point from one window's coordinate system into another's, and throws in which child window…
- XTrapDigital Equipment's X extension for capturing and replaying input — the predecessor of XTEST and RECORD, the pair that…
- xtrlockAn X11 lock that hides nothing: the screen stays visible, but the pointer turns into a padlock and nothing responds until…
- XTS modeA block cipher mode for disk encryption that tweaks each block by its sector number and position, instead of using an IV.
- Xuejia LaiChinese cryptographer who designed the IDEA block cipher with James Massey and later co-authored the paper that broke MD5.
- XUI (DECwindows)DEC's toolkit for DECwindows — the programming interface Motif was built on, which is why Motif looks like HP but feels like…
- xUnitCollective name for the family of unit testing frameworks descended from SUnit, written by Kent Beck for Smalltalk in 1994…
- XvfbAn X server with no screen: it draws everything into memory so graphical programs can run where nobody is looking.
- XVideo (Xv)The X11 extension that let the graphics card scale and colour-convert video so the CPU didn't have to.
- XViewSun's OPEN LOOK toolkit for X, built so SunView programs could move house without being rewritten.
- XvMCThe extension to XVideo that, around 2001, let the graphics card take over motion compensation in MPEG-2 decoding so a…
- XwaylandAn X server that is itself a Wayland client, so old X programs can run on a Wayland desktop without noticing the switch.
- xwdX Window Dump: the screenshot tool that ships with X11, and the peculiar image format nobody else wanted.
- xwininfoThe X11 tool for pointing at a window and finding out what it actually is: id, size, position, depth and visual.
- XXEXML External Entity attack. Exploit XML parser that processes external-entity references → read local files, do SSRF, DoS…
- XXE injectionXML External Entity injection — a vulnerability where an XML parser is tricked into processing external entities the…
Y
- Y Combinator (YC)The world's most famous startup accelerator — invests small amounts in early startups, runs 3-month batches twice a year…
- Y Window SystemMark Thomas's 2004 attempt to write a window system from scratch rather than patch X: a server with widgets and window…
- Y-sortingDraw order in top-down games is decided by each object's y-coordinate, so things lower on screen overlap the least.
- yabridgeA bridge that runs Windows audio plugins inside a Linux DAW by loading them under Wine and shuttling the audio across the…
- Yael Tauman KalaiThe cryptographer who co-invented ring signatures and later showed how to check a computation without redoing it.
- YAGNI (You Aren't Gonna Need It)Principle: don't build features until you actually need them.
- YahooThe web's first great front door: a hand-built link directory that became a portal and later a case study in missed deals.
- Yahoo JapanThe Japanese Yahoo portal, launched by SoftBank, which outlived and long outshone its American parent.
- Yahoo MessengerYahoo's instant-messaging client, 1998–2018, one of the 2000s' big chat apps alongside AIM and ICQ.
- Yahoo PipesYahoo's visual tool (2007–2015) for wiring together and mangling web feeds with drag-and-drop.
- Yamaha CS-80Yamaha's eight-voice analogue synth from 1977: expressive, temperamental, close to a hundred kilos and immortalised by…
- Yamaha DX7The first digital synth to sell in truly large numbers, and the sound of the 80s power ballad — the electric piano, the…
- Yamaha NS-10A hi-fi speaker the hi-fi press panned, which then sat on nearly every mixing desk in the world for twenty years.
- Yamaha XGYamaha's 1994 answer to Roland GS: an even bigger superset of General MIDI with hundreds of extra voices and several effect…
- YAML (YAML Ain't Markup Language)Human-readable config format — indentation instead of braces, comments allowed.
- YandexThe Russian search engine that beat Google at home and was then split in two by geopolitics.
- Yann LeCunDesigned the convolutional networks that made computer vision possible — and had them in commercial service back in the…
- Yanoff listA regularly updated text file listing everything you could connect to on the internet — the precursor to web directories…
- YARAA rule language for recognizing malicious code by patterns in files. Created by Victor Alvarez at VirusTotal and released in…
- YARA ruleA rule format for identifying and classifying malware based on patterns — text strings, byte sequences, or conditions in a…
- YarnJavaScript package manager. Facebook + Google + Exponent, October 2016. Was faster than npm v3 → pushed npm to improve. Yarn…
- YaRN scalingYet another RoPE extensioN — a refined method (2023) for extending the context length of RoPE models, which scales different…
- Yarn SpinnerA dialogue tool for games that writes conversations as nodes in a screenplay-like format, best known from Night in the Woods.
- Yarrow (PRNG)Counterpane's 1999 cryptographic random number generator, for years the engine behind /dev/random on FreeBSD and macOS.
- YaSTSUSE's answer to "why should configuration be scattered across twenty files?" — one tool for installation and system…
- Yehuda LindellIsraeli cryptographer, co-author of the standard modern cryptography textbook and one of the people who moved secure…
- YelpUser reviews of restaurants, plumbers and dentists – plus a permanent tug-of-war over whose reviews get shown.
- yEncThe encoding that cut Usenet binaries by nearly a third, on the bet that the network could finally handle eight bits.
- yescryptThe password hash that quietly took over /etc/shadow on most major Linux distributions.
- Yevgeniy DodisNYU cryptographer best known for fuzzy extractors, the way to get stable keys out of noisy sources like fingerprints.
- yieldKeyword that pauses a function and returns a value — picks up where it left off on the next call.
- Yik YakAn anonymous feed that only showed posts from people within a few miles. An experiment in how badly things go when anonymity…
- YjsJavaScript CRDT library for conflict-free real-time collaboration. Powers collaboration in Notion-likes, Figma, Tldraw…
- YM formatChip-music format that stores, frame by frame, exactly what the YM2149 sound chip wrote to its registers.
- YM2612Yamaha's FM synthesis chip that gave the Sega Mega Drive its punchy, bass-heavy voice.
- YMODEMChuck Forsberg's extension of XMODEM: bigger blocks, filenames up front, and several files in one sweep.
- Yo-yo attackA cryptanalytic technique that alternately encrypts and decrypts a pair of messages so that a relation between them survives…
- YokogawaJapanese process-automation firm whose CENTUM was one of the world's first distributed control systems (DCS).
- Yoongu KimLead author of the 2014 paper showing you can change bits in DRAM without ever writing to them.
- You.comAI-driven search engine that blends traditional search results with LLM-generated answers + citations. Pivoted to "research…
- YouTubeThe world's largest video platform — Chad Hurley, Steve Chen, Jawed Karim (2005), bought by Google in 2006 for USD 1.65…
- YouTube ShortsYouTube's answer to TikTok. Launched 2020 (India first — TikTok ban market), globally 2021. Max 60 sec vertical video…
- YQLYahoo's SQL-like service from 2008 that let you query the whole web as if it were a database — shut down in 2019.
- YSlowYahoo's 2007 browser add-on that graded page performance A–F and turned front-end optimization into a discipline of its own.
- ytalkA Unix talk client that handled more than two participants and, just as importantly, spoke both the old and the new talk…
- YubicoSwedish company that turned two-factor login into something you hang on your keyring.
- YubiHSMYubico's USB-sized hardware security module, an HSM that fits in a USB port rather than a server rack.
- YubiKeySwedish-founded hardware security key — USB/NFC, FIDO2/WebAuthn, U2F, OTP, PIV, OpenPGP, no password attack works against it.
- YugabyteDBA distributed SQL database (2017) that is wire-compatible with PostgreSQL — it actually reuses the Postgres query layer on…
- YUIYahoo's JavaScript library from 2006 — a heavyweight of the early front-end era, retired in 2014.
- Yukihiro MatsumotoDesigned Ruby with a stated goal unusual for a language: to make the programmer happy.
- Yuval IshaiIsraeli cryptographer whose speciality is making expensive primitives cheap by borrowing them from one another.
- Yuval YaromThe researcher behind Flush+Reload, the cache attack that became a building block for much of modern side-channel work.
- Yvo DesmedtBelgian cryptographer usually credited as the father of threshold cryptography: the idea that a private key can be used…
Z
- Z-bufferThe buffer tracking how far away each pixel is, so nearer objects hide what lies behind them.
- Z-fightingThe flickering that appears when two surfaces sit so close in depth that the z-buffer cannot decide which one is in front.
- Z-machineInfocom's virtual machine for text adventures: write the game once, write a small interpreter per computer.
- Z-NetzA German BBS network from the late 1980s, built around the Zerberus mailbox software and its hierarchical discussion boards.
- Z-prepassRendering the whole scene with depth only and no color first, so the second pass shades each pixel exactly once.
- Z-WaveA wireless protocol for smart homes that builds a mesh network between devices (lights, locks, sensors). It runs on sub-GHz…
- Z39.50The library world's protocol for searching remote catalogues, standardised in 1988 and still quietly running behind many…
- Zakir DurumericThe researcher who turned scanning the entire IPv4 internet into an afternoon job.
- Zap (Lightning)A Bitcoin Lightning micropayment sent as a reaction to a post, primarily on Nostr. Instead of a free "like" you send a few…
- Zaphod modeRunning several monitors as entirely separate X screens, :0.0 and :0.1, so each has its own root window and windows cannot…
- Zapier"When X happens in app A, do Y in app B" — automation platform with 7000+ app integrations. Bootstrapped for years without…
- ZCAVZoned constant angular velocity — spin the disc at a fixed rate but pack more sectors into the roomier outer zones.
- Zebra TechnologiesThe dominant name in label printing, whose ZPL command language is so entrenched that competitors emulate it.
- ZedRust-written editor by Nathan Sobo et al. (the Atom creators). Stealth in 2022, stable in 2024. Native GUI, GPU-accelerated…
- ZellijTerminal multiplexer written in Rust, first released in 2021 (originally called Mosaic). tmux, but discoverable — the…
- Zen and the Art of the InternetA 1992 beginner's guide to the internet, written by a student and given away over the very network it described.
- ZendeskThe customer support system three Danes wrote in a Copenhagen loft in 2007, moved to San Francisco and sold for ten billion…
- ZeniMax MediaThe holding company sitting above Bethesda, id Software and Arkane — bought by Microsoft for $7.5 billion in 2021.
- Zenith Data SystemsTV maker Zenith's computer arm, grown out of the Heathkit kit business and for a while one of the biggest PC suppliers to…
- ZephyrMIT's notification system from Project Athena — instant messaging before anyone needed the phrase.
- ZeRO (Zero Redundancy Optimizer)Microsoft's technique for training large models by no longer storing the same thing on every GPU. It partitions optimizer…
- Zero crossingThe point where a waveform changes sign and passes through zero — the one place a cut is guaranteed not to pop.
- Zero paddingFilling the last block with null bytes: simple, but ambiguous when it comes to removing the padding again.
- Zero trust networkSecurity model: zero trust is based on network location. Every request is verified with identity + device posture + context…
- Zero window probeA small packet the sender emits periodically to a receiver that said "I'm full", asking whether room has appeared after all.
- Zero-bubble pipelineA schedule that removes the idle time in pipeline-parallel training by splitting the backward pass in two halves and…
- Zero-correlation attackAn attack that finds linear approximations with exactly zero correlation, giving a way to tell the cipher apart from random.
- Zero-cost abstractionThe principle that an abstraction must cost nothing at runtime: what you don't use you don't pay for, and what you do use…
- Zero-day (0-day)A security flaw attackers know about but the vendor doesn't — "zero days" to fix before the first attack.
- Zero-day exploit (0day)An exploit for a vulnerability the vendor doesn't know about — "zero days have passed since discovery".
- Zero-delay feedback (ZDF)A digital filter technique that resolves feedback within the same sample, so resonance and modulation behave as they would…
- Zero-knowledge proofCryptographic proof where a prover convinces a verifier that a statement is true without revealing why it's true (e.g. "I…
- Zero-shot learningModel solves a task without seeing any examples — only via instruction. Opposite: few-shot (a few examples in the prompt)…
- Zero-trustA security model where no trust is granted based on network position — everything is verified on every request.
- ZerodiumAn American exploit broker that buys zero-days from researchers, resells them to governments, and publishes its purchase…
- ZeroizationOverwriting key material in memory so that it cannot be read back after use.
- ZerologonA cryptographic flaw in Netlogon that let anyone with network access to a domain controller take over the whole domain in…
- ZeroMQ (ØMQ)Brokerless messaging library — pub/sub, req/rep, push/pull patterns. "Sockets on steroids". Library, not a server.
- ZeroTierA mesh VPN/SDN that creates virtual Ethernet networks (L2) over the internet — devices around the world behave as if they…
- ZFSThe most capable filesystem freely available — copy-on-write, snapshots, compression, RAID built in.
- ZFS PoolZFS storage aggregate: combines multiple vdevs (mirror, RAID-Z, single-disk) into a pool from which datasets allocate…
- Zhipu AITsinghua spinoff behind the GLM and ChatGLM models — one of the first Chinese labs to release open weights, and one of the…
- ZIF socketZero Insertion Force — a socket design where the chip is placed in without needing to press, and a lever then clamps the…
- ZigSystems language by Andrew Kelley, 2016 — "C without footguns but without Rust's borrow-checker difficulty". No GC, explicit…
- ZigbeeLow-power mesh radio for IoT — smart bulbs, sensors, locks. Built on IEEE 802.15.4.
- ZilogThe Intel defectors' company, which built a processor so successful that the rest of its history is about failing to do it…
- Zilog Z80Faggin left Intel, built a better 8080, and sold it for forty-eight years.
- Zimmermann TelegramAn encrypted German telegram from January 1917 that British codebreakers read, and that helped pull the United States into…
- ZINKPhoto paper with the colour already cast in — the printer contributes nothing but heat, hence Zero Ink.
- ZIPMost-used archive format. Phil Katz, PKWARE, 1989 (for MS-DOS PKZIP). Per-file compression with DEFLATE. Cross-platform…
- Zip driveThe floppy that held a hundred megabytes — and became notorious for a clicking noise meaning both this disk and the next one…
- Zipper noiseA crackling artefact produced when an audio parameter changes in steps rather than smoothly, normally cured with parameter…
- ZK-rollupA layer 2 that bundles thousands of transactions and submits a cryptographic proof that all of them were valid.
- zk-SNARKZero-Knowledge Succinct Non-interactive ARgument of Knowledge — compresses a computation proof to ~200 bytes that verifies…
- zk-STARKScalable Transparent ARgument of Knowledge — zero-knowledge proof with no trusted setup, built only on hash functions…
- ZMODEMThe BBS era's file transfer protocol — streaming, self-resuming, and clever enough to start the download for you.
- zMUDA Windows MUD client from Zugg Software, known for triggers, scripting and automatic mapping.
- ZNCAn IRC bouncer: a program that stays connected to the IRC network around the clock and that your own client connects to in…
- Zobrist hashingA way to hash board positions by XORing together one random number per piece and square — and updating the hash with two…
- ZodTypeScript library for runtime schema validation. It solves what TypeScript can't: types vanish at compile time, so incoming…
- Zodiac cipherA 340-character cipher the Zodiac killer sent to a newspaper in 1969, which was not solved until 2020.
- ZohoIndian SaaS company with around fifty business apps, grown large without a cent of venture capital.
- Zombie POODLEPOODLE back from the dead in 2019, this time in TLS 1.2 implementations that leaked padding errors in new and inventive ways.
- Zombie processA process that has exited but whose exit status nobody has collected — it is dead, yet still occupies a slot in the process…
- Zombo.comA site from 1999 consisting of a loading animation that never completes and a voiceover explaining that you can do anything…
- Zone bit recording (ZBR)Splits the disc into concentric zones and packs more sectors into the longer outer tracks instead of wasting their extra…
- Zone Mail HourThe one hour a day when every FidoNet node in a zone had to accept netmail — and keep human callers out.
- Zone master key (ZMK)The key-encryption key two parties in the payments chain share so they can send each other working keys.
- Zoned bit recording (ZBR)Outer tracks are longer, so they get to hold more sectors — otherwise half the platter is wasted.
- ZonegateA designated FidoNet node that carried private netmail between zones, so not every BBS had to phone another continent.
- Zoo (archive format)A portable archiver from 1986 that turned up everywhere ARC didn't — Unix, VMS and the Amiga — until LHA took over.
- Zooko Wilcox-O'HearnThe cypherpunk behind Zooko's triangle, the Tahoe-LAFS file system and the Zcash cryptocurrency.
- ZoomThe video meeting service that became a verb in 2020. Founded in 2011 by Eric Yuan, previously head of engineering for Cisco…
- ZorkMIT's answer to Colossal Cave: a text adventure with a parser that understood whole sentences, and the game that gave MUD…
- Zorro busThe Amiga's expansion bus, which configured its own cards a decade before the PC discovered plug and play.
- ZotacHong Kong brand owned by PC Partner that builds Nvidia graphics cards and ZBOX mini-PCs.
- ZPLZebra's command language for label and barcode printers, where ^ commands build the label field by field.
- zramA Linux feature that creates a compressed block device in RAM, most often used as fast swap. Instead of swapping to slow…
- ZscalerMoved the corporate firewall into the cloud and routed everyone's traffic through itself on the way.
- Zsh (Z shell)A Unix shell written by Paul Falstad in 1990, named after a colleague's username "zsh". Since macOS Catalina (2019) the…
- ZTEShenzhen telecom equipment maker, Huawei's partly state-owned neighbour, and the company that showed how dependent Chinese…
- ZTNAZero Trust Network Access — a model that grants access to specific applications based on verified identity and context…
- ZUCA Chinese stream cipher that became one of the standard algorithms in LTE networks, named after mathematician Zu Chongzhi.
- ZulipA chat tool whose entire premise is that every message belongs to a topic inside a channel. No thread is optional — you pick…
- Zuse S1Konrad Zuse's forgotten machines: relay computers built to do exactly one thing, namely calibrate the wings of a glide bomb.
- Zuse S2Arguably the first process-control computer — a relay machine that read sensors on an aircraft wing and recomputed the…
- Zuse Z1A fully mechanical binary computer cut from sheet metal in his parents' living room, which never ran for more than a few…
- Zuse Z2The stopgap that swapped hand-cut sheet metal for second-hand telephone relays, and thereby paid for the Z3.
- Zuse Z3The first automatic program-controlled computer that actually worked, assembled from telephone relays in a Berlin apartment…
- Zuse Z4The relay machine that fled Berlin by lorry, hid in an Alpine barn, and in 1950 became the only working computer on the…
- Zustand"German for bear" — minimalist state library, 1.2 KB gzipped, hooks-based API. Created an entire "tiny state libs" wave.
- Zvika BrakerskiIsraeli cryptographer at the Weizmann Institute, present at nearly every step that made homomorphic encryption practical…
- ZX PrinterSinclair's spark printer for £49.95 — output on silvery metallic paper that a generation of Britons remembers with mixed…
- ZX SpectrumClive Sinclair's cheap box with rubber keys, which handed Britain an entire games industry.
- ZX Spectrum NextAn FPGA-based evolution of the ZX Spectrum, crowdfunded on Kickstarter and cased by the original's designer.
- ZX81Sinclair's black-and-white micro from 1981 with 1 KB of memory, which sold the home computer to people who had never…
- Zygalski sheetsSome hundred and fifty perforated paper sheets stacked on a light table until light came through in exactly one place…
- ZynAddSubFXOpen-source software synth with three synthesis engines and a name that is harder to pronounce than it is to program.
- ZyngaThe company behind FarmVille, which for a few years turned the Facebook news feed into a stream of requests to water…
- ZypperopenSUSE's command-line package manager — zypper in is roughly what apt install is to the Debian world.
- ZyXELTaiwanese modem maker from the BBS era that now mostly builds firewalls and the DSL boxes ISPs post to their customers.
- Zzap!64British Commodore 64 games magazine launched in 1985, famous for letting several reviewers disagree on the same page.