Linux is an open source alternative operating system to Windows and Mac OS X. It has minimal system requirements and runs on almost any hardware. Some key advantages of Linux include being free, more secure due to lack of need for antivirus software, and more customizable. Popular Linux distributions for desktop use include Ubuntu, Fedora, Mint, and openSUSE. Ubuntu is one of the most popular and offers both desktop and server editions. While Linux has fewer proprietary application options and potential driver issues, it provides many free and open source alternatives to common Windows applications.