“Like Roberts's first paper outlining the proposed Arpanet seven years earlier, the Cerf-Kahn paper of May 1974 described something revolutionary. Under the framework described in the paper, messages should be encapsulated and decapsulated in "datagrams," much as a letter is put into and taken out of an envelope, and sent as end-to-end packets. These messages would be called transmission-control protocol, or TCP, messages. The paper also introduced the notion of gateways, which would read only the envelope so that only the receiving hosts would read the contents.”