Linux. You've obviously heard of it (after all, you got here, didn't you?), but what is it, really?
First, a bit about how computers work. There are two parts to a computer--the hardware and the software. The hardware is the "pieces"--the monitor, the keyboard, the hard drives, the CPU, and so on. The software is the set of instructions (or programs) that make the computer work. Some programs, like Microsoft Office, or Firefox, or iTunes, are considered applications. They're the part most of us think of as programs. They are the software that lets us get stuff done.
Underneath the applications are the computer instructions that tell the computer how to work--how to access the disc drives. How to put a window on the screen. How to connect to the internet. How to keep all the pieces working together, playing nice, and getting along. These instructions are the operating system or OS. Microsoft Windows (in all its flavors--Windows 7, XP, Vista, etc) and Mac OSX are two examples. Linux is another.
Linux is based on a decades-old, tried-and-true operating system called Unix that goes back to the early days of computing. It began as an operating system for big computers (we're talking room-sized here), but it's power and stability was attractive to users of small computers as well. So, in 1983 a group of programmers created a "Unix-compatible" OS called Linux.
Linux runs on many different types of hardware, including personal computers, phones, network hardware (such as cable routers), and more. The version we'll focus on in this blog is the personal computer version.
Most computers today come with the OS pre-installed. Unless of course, you build one yourself, or buy a bare-bones system without an OS. So, if you have an OS already, why change to Linux? The answer to that question is a blog post in itself--there are several reasons, including a desire for better stability and security, better performance on less-powerful hardware, or even just a desire to learn something new or try something different.
Whatever the reason for your interest in Linux, I think you're going to enjoy it. The OS has come a long way in its history, and it is getting better all the time.