TCP/IP - 1982
In 1974, Transmission Control Protocol (TCP), which replaced the Network Control Program (NCP), and Internet Protocol (IP) were introduced.
"Bob Kahn and Vint Cerf introduced what’s called TCP – Transmission Control Protocol – to allow everybody to use a common set of protocol standards. Danny Cohen recognized that TCP was inadequate to carry streaming data. … Danny Cohen and a couple of others insisted that TCP be broken into what we now call TCP/IP, with IP being the internal network protocol and TCP being the end-to-end. In 1978, it became very important to make that split so that we can now have what we use so much of – namely streaming media."
- Leonard Kleinrock, 3/13/13
Protocol standardization allowed separate networks to be connected, making the ARPANET part of a much larger network.