We celebrated the 40th anniversary of the Internet less than 2 years
ago:
The ARPAnet was a WAN (wide area network) and not an Internet, but it
was one of the three networks involved in that first test on November
22, 1977 (after a two network test the previous year). The option to use
TCP/IP in addition to the native NCP became popular on the ARPAnet to
the point that NCP was turned off in 1983. It was hardly the only
network to get assimilated into the Internet, but it was the one with
the most impact. That makes the 50th anniversary of the first ARPAnet
packet an important milestone in Internet pre-history.
-- Jecel