Octet

An octet is an 8-bit unit of data. Although the term byte is now basically a synonym, a separate term was needed in the early days of work on the TCP/IP protocol suite, because in the earlier NCP protocol suite of the ARPANET, 'bytes' of variable length were supported. (That was as a result of the prevalence of machines such as PDP-10, a 36-bit word machine whose ISA directly supported variable-length bytes.)