TCP/IP: a network of networks

By the early 1970s ARPANET worked, but it was one network among several, each built its own way. A computer on one could not talk to a computer on another. Connecting them meant agreeing on something none of them yet shared.

In May 1974 Vint Cerf and Bob Kahn published “A Protocol for Packet Network Intercommunication” in IEEE Transactions on Communications. Its premise was modest and radical at once: leave each network as it is, put gateways between them, and let the hosts at the edges take responsibility for getting data through intact.

Nine years later, every host on ARPANET had a deadline to start speaking that language.