Linux was developed by Linus Torvalds
and other programmers in 1991 while Linus was a student a the University
of Helsinki. Linus wanted a desktop version of unix which ran on modest
hardware and didn't cost so much. He began writing the code based on minix
and then released it to the public so that it could be improved upon. Other
programmers in the spirit of GNU worked together to develop what we now
take for granted, a derivative of Unix designed to be fast, small,
and reliable and most importantly free.
At the heart of Linux is the kernel which basically runs the show. It controls for instance how much time to allot a process and tries to balance this with all of the rest the processes that are running. Last I heard around version 2.0.35 it contained around 500,000 lines of code. The current stable kernel is 2.2.7 although the various vendors now ship anything from 2.2.3 to 2.2.5. This of course is only part of the operating system which includes Xwindows and any other programs or processes that are running.
Linux is unique because it does what a microsoft operating system does not. It works. That not to say windows does not have its merits, it just that once you learn the basics of Linux you will not go back. It also runs on more hardware architectures then any other operating system (X86, Alpha, Sparc, PPC, StrongArm, and many others). A Linux machine can act as a graphical workstation (Titanic was rendered on Linux), as a general business desktop, or any number of servers. For example a web server, an email server. file and print server. Basically anything NT can do, but better. Did I mention it can do all of this at once for free?
Well those are the bare basics these facts are repeated all over the internet and in much greater detail then I have have to urge to explain.
Installing RedHat Linux