Linux is an operating system similar to Microsoft Windows and Mac OS. There is a large number of linux distributions (versions). Most of those distributions are free to download, install, customize for business or personal use, but not to resell an existing code.

One of the most popular distributions today is called Ubuntu it very easy to install and use even for a notive user. Operating system supports a large number of peripheral devices and will automatically install all the neccessary drivers to provide and excellent out-of-the-box experience.

Just like Windows XP or Vista and Mac OS X it has it's own version of Windows driver operating system. It has a "start" button, menus, it gives you access to files and folders and the Internet. You can run Firefox and many other popular programs on Linux.

Many small businesses use Linux as an alternative to other commercial server software. It cuts overhead dramatically in terms of licenses.