Beej is often on here and can confirm the actual inception date, but iirc I used it as far back as at least 1999/2000ish
I used it as a companion to Richard Stevens' classics on TCP/IP.
> I'd started off with Beej's Guide to Network Programming back in 1995 or so
It helped me write some chatroom bots for things like IRC and battle.net in the early 2000s, which fueled the hobby even more and eventually turned it into a very good career. :)