Many commercial companies were involved in the development of UNIX through the 70's and 80's. The UNIX code, development rights, and licensing for it changed hands multiple times during this time frame. In addition, free and/or open source versions sprung up from multiple sources. One such version was Minix (literally Minimal UNIX), a small, open source UNIX version created by Andrew Tanenbaum.
It was this version of UNIX that Linus Torvalds used to model a project that he termed was "just for fun". He wanted to be able to use a form of UNIX on the hardware he was currently working with and ended up creating the whole thing himself. Not long after, he realized what he had inadvertently created was an Operating System Kernel. Around this time, he posted the following on Usenet:
"Hello everybody out there using minix - I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones. This has been brewing since april, and is starting to get ready. I'd like any feedback on things people like/dislike in minix, as my OS resembles it somewhat (same physical layout of the file-system (due to practical reasons) among other things)."
How did these humble beginnings result in one of the most popular Operating Systems in use today?