Wow, this was about, well, 18 years in the making.... Aug. 25, 1991 is when Linus first posted about Linux, so happy birthday Linux!!
1991: Linus Torvalds, a 21-year-old university student from Finland, writes a post to a user group asking for feedback on a little project he's working on. He's built a simple kernel for a Unix-like operating system that runs on an Intel 386 processor, and he wants to develop it further. The kernel eventually becomes Linux, which is released in 1994 and distributed over the internet for free.