8-bit
Eight bits is enough for 256 values, one character, or an entire generation of home computers.
Processors like the 6502, the Z80 and Intel's 8080 worked eight bits at a time but addressed memory with sixteen, giving 64 kibibytes to move around in. That sufficed for the Commodore 64, the ZX Spectrum, the NES and the whole home computer wave around 1980. Programs were written in assembly out of necessity, and the machines were simple enough for one person to understand completely.
Eight bits also became the standard size of a byte, after early machines had experimented with six, seven and nine. Today the term survives mostly as an aesthetic — the limited palette and visible pixels of games deliberately imitating the era — and in contexts like 8-bit quantisation, where neural networks are shrunk to fit in memory.