1st January, 1983
A full switchover to TCP/IP was performed on the ARPANET
Google celebrates this milestone with a new logo today!

One of the more interesting challenges was the transition of the ARPANET host protocol from NCP to TCP/IP as of January 1, 1983. This was a “flag-day” style transition, requiring all hosts to convert simultaneously or be left having to communicate via rather ad-hoc mechanisms. This transition was carefully planned within the community over several years before it actually took place and went surprisingly smoothly (but resulted in a distribution of buttons saying “I survived the TCP/IP transition”).