Linux, together with a set of GNU programs, is an operating system. That is, Linux is not a single program or a suite of tools. Most "versions" of Linux, known as "distributions", are available to download free of charge. However, there are some things you should know about downloading and installing Linux:
First, you don't have to actually install Linux in your hard disk to use the Linux operating system. There exist several "versions" of Linux that can be downloaded and burned to a CD. These variants of the Linux operating system, known as "Live CD" versions, will boot Linux directly from the CD on systems that are capable of doing this. (most PCs manufactured in the last 7 to 8 years will allow this). Memory requirements vary, so please consult our list of Live CD distributions on our distributions page (choose the option 'Live CD' from the 'Category' menu). There are several popular Live CD distributions, such as MEPIS, Knoppix and Slax. Most major Linux distributors (SUSE, Mandriva, Ubuntu) also offer Live CD versions of their products.