Linux (commonly pronounced LIN-iks in English, also pronounced LIN-ooks) is a generic term referring to Unix-like computer operating systems based on the Linux kernel. Their development is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License.

Linux can be installed on a wide variety of computer hardware, ranging from embedded devices such as mobile phones, smartphones and wristwatches[7][8] to mainframes and supercomputers.[9][10] Linux is predominantly known for its use in servers; in 2007 Linux’s overall share of the server market was estimated at 12.7%, while a 2008 estimate suggested that 60% of all web servers ran Linux. Most desktop computers run either Mac OS X or Microsoft Windows, with Linux having only 1.2% of the desktop market. However, desktop use of Linux has become increasingly popular in recent years, partly owing to the popular Ubuntu distribution and the emergence of netbooks and smartbooks.

Typically Linux is packaged in a format known as a Linux distribution for desktop and server use. Linux distributions include the Linux kernel and all of the supporting software required to run a complete system, such as utilities and libraries, the X Window System, the GNOME and KDE desktop environments, and the Apache HTTP Server. Commonly-used applications with desktop Linux systems include the Mozilla Firefox web-browser, the office application suite and the GIMP image editor.

The name “Linux” comes from the Linux kernel, originally written in 1991 by Linus Torvalds. The main supporting Userland in the form of system tools and libraries from the GNU Project (announced in 1983 by Richard Stallman) is the basis for the Free Software Foundation‘s preferred name GNU/Linux.