Today's the 13th anniversary of the first post published to the first Fediverse system. On May 18th, 2008, Evan Prodromou published for the first time on Identi.ca:
https://web.archive.org/web/20130615111045/http://identi.ca/notice/1
The folks at Fediverse Party have been marking this occasion as the Birthday of the Fediverse:
https://fediverse.party/en/post/fediverse-12-years-in-2020
https://fediverse.party/en/post/fediverse-13-2021-party-time
13 years is a significant milestone for the Open Web, here's to many more!