If you've never installed an operating systems onto your computer (like a new version of Windows or Mac OS), then you might find it easiest to purchase a computer that already runs Linux. A complete list of vendors can be found at linuxpreloaded.com but here is an abbreviated list:
Of course you don't need to buy a new computer just to get Linux. You can install it yourself, although if you're not a computer expert then you might want to get help from your local computer geek or purchase a good book or magazine like Linux Identity.
Using a live CD means that Linux will be running on your computer without installing anything. It's a risk-free way to try and see by yourself what Linux is. And of course Live CDs are free to download from any Linux distribution.
When running on a live CD, your computer uses solely the CD-ROM to work (without accessing the hard drive inside). You can launch all of the default programs, edit documents, and browse the web.
Since it is only designed as a trial mode, it is a little slow (it will take you five minutes to boot up, and programs launch somewhat slowly). If you proceed to install, the system will go much faster.
When you're ready to install, all you have to do is backup your personal data, and install Linux onto your computer. From there, the rest of this website will help you find your way around.