Internet Protocol/Definition

The highly resilient set of rules for how messages are sent across the internet, first by being broken into smaller packets (each with the endpoint address attached), then moving among many mid-points by unpredictable routes, and finally being reassembled into the original message at the endpoint. IP version 4 (IPv4) is from 1980 but lacked enough addresses for the entire world and was superceded by IP version 6 (IPv6) in 1998.