CERN celebrates 30th anniversary of the World Wide Web • The Register:

On April 30, 1993, CERN signed off on a decision that the World Wide Web – a client, server, and library of code created under its roof – belonged to humanity (the letter was duly stamped on May 3).

"CERN relinquishes all intellectual property rights to this code, both source and binary form, and permission is granted for anyone to use, duplicate, modify and redistribute it" states a letter signed on that day by Walter Hoogland and Helmut Weber – at the time respectively CERN's director of research and director of administration.