Internet
Global network of networks running the TCP/IP protocols. Roots in ARPANET 1969, commercialized 1995, ~5.5 billion users in 2024.
Technical milestones: ARPANET (1969), TCP/IP design Vint Cerf + Robert Kahn (1974), DNS (1983), Tim Berners-Lee's World Wide Web (1989–91). Governance: ICANN (domain names + IP allocation), IETF (protocol standards via RFCs), W3C (web standards). Physical layers: optical fiber (transatlantic cables), satellite (Starlink), mobile (4G/5G). The word "Internet" is increasingly spelled "internet" (lowercase) in modern style guides.