Linux...

[Smith]

i no this sounds stupid, in mybye 5 sentences, wut exactly is linux?

[LSA]

Linux is an operating system, but in it's purest form it is only a kernel.

It was started by Linus Torvalds in 1991, and is open source, meaning that anyone can download the source code free and modify it, and give it away for free.

EDIT: http://filesharingtalk.com/index.php?showtopic=95750