Linux is one of several freely available operating systems.
Linux and FreeBSD are a couple of my principle hobbies -- they are also tools that I use extensively.
One minor contribution I've made is to create a patxh to allow tripwire to complile cleanly under Linux. However, this is probably unnecessary now since you can get RPM's (packages) of the sources and precompiled package. Try a mirror if those sites are busy.
Tripwire is a tool for detecting changes in files due to corruption or tampering. You can find the full Tripwire package at The COAST Archive at Purdue University (via HTTP or FTP).
I've made somewhat more impact as the Linux Gazette Answer Guy. I didn't make up the name -- honest -- it all started when, while writing a Letter to the Editor, I noted that many of the letters I'd already seen were clearly looking for the house techy, and if the question was on a certain band of subjects, I'd be willing to give it a shot. The first month she sent me 5, I copied her on my replies (so she'd know these people weren't just sent to deep space) ... and she published them as a column. It snowballed from there. Later Heather took over the HTML and drew up new graphics for it, allowing the column to be much more navigable and search-engine friendly.
Linux is a big subject, which I spend a fair amount of time investigating. Since Linux is a "product" of the Internet almost all of the work and documentation that's relevant to it is available on the web.
The official sources for the Linux kernel are now at The Linux Kernel Archives which is apparently sponsored by Transmeta Inc. -- the company where Linus Torvalds works.
Linus is, of course the "father" of Linux. He started the phenomenon back in about 1992 (?) and invited readers of the comp.os.minix newsgroup (actually I think it was "alt.os.minix" back then, but things have changed since then) to play with his code.
Given the anarchy that characterizes the development of Linux its a little hard to call it a "project." In one sense Linux is "just" a kernel. The sources for that kernel are maintained by Linus -- and parts of it have been written by lots of people.
In other senses Linux is an incarnation of the GNU project. It provided a kernel to allow the Free Software Foundation's code function as a stand alone operating system. Richard Stallman (rms) the founder of the GNU project has occasionally raised some controversy regarding this. By contrast, GNU is a project -- which a central spokesperson and an official plan and policy. It is also working on it's own kernel, called the HURD ("HIRD of Unix Replacement Daemons" where HIRD, in turn, stands for "HURD of Interfaces Representing Depth *)
While the Linux kernel is released under the GNU Public License (GPL) it is not part of the GNU project. So, although, large parts of a typical Linux distribution or installation are GNU -- it isn't quite right to say that Linux is "just" a GNU system.
It is conceivable that someone could create a complete Linux distribution using all BSD, public domain, and other non-GNU software (although it would probably still need to be built with gcc, the GNU C compiler). In fact I think there are some "X terminals" which are really a combination of the Linux Kernel and XFree86 without basically no officially GNU "products" embedded in the system. Like I said, Linux is the product of concerted anarchy.
As a result of all this wonderful anarchy it's difficult to say anything definitively about the subject. I can't simply point to one place with a link that says the official Linux web site.
However, I've gathered a sampler of the sites that I think are the best Linux resources overall.