Our favorite operating system kernel is 21 years old now. Back in 25th August, 1991, Linus Torvalds, the creator of Linux, made this announcement in comp.os.minix newsgroup:

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).

I've currently ported bash(1.08) and gcc(1.40), and things seem to work. This implies that I'll get something practical within a few months, and I'd like to know what features most people would want. Any suggestions are welcome, but I won't promise I'll implement them :-)

PS.  Yes - it's free of any minix code, and it has a multi-threaded fs. It is NOT protable (uses 386 task switching etc), and it probably  never will support anything other than AT-harddisks, as that's all I have :-(.

So what Linus assumed to be a 'won't be big and professional' has grown with leaps and bounds and now used almost everywhere you can imagine -- from mobile phones to super-computers, from home equipments to space, from small desktop computers to those massive servers serving millions of pageviews a day. Linux has almost dominated all large technological fields known to mankind.

With 21st birthday comes a hell lot of good news. The Linux 3.6 kernel is going to be out soon, Ubuntu will ship with 5% of PCs and Steam is finally coming to GNU/Linux. Android is already the leading mobile platform.

We at Muktware raise a glass and wish a long and exciting journey ahead of this revolution.