On this day, 15 years ago the http-state working group was created in #IETF. https://daniel.haxx.se/blog/2009/01/09/ietf-http-state-group-created/
27 months later the cookie RFC 6265 was published: https://daniel.haxx.se/blog/2011/04/28/the-cookie-rfc-6265/
This spec is now being revised. The latest draft is called -13 and lives here: https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-rfc6265bis-13