Ubuntu is a free operating system based onDebian. Its name comes from the Zulu word "ubuntu", loosely translated as "humanity", describing the ubuntu philosophy: "I am who I am because of those around me," a positive aspect of community. Ubuntu's goals include providing an up-to-date, stable operating system for the average user, with a strong focus on usability and ease of installation. Ubuntu has been rated as the most popular Linux distribution for the desktop, claiming approximately 30% of desktop Linux installations in a survey by desktoplinux.com.

Ubuntu is free and open source software, meaning it is free to download and use without monetary charge and is free to be modified and improved upon. Ubuntu is sponsored by the UK-based company Canonical Ltd, owned by South African entrepreneur Mark Shuttleworth. Instead of selling Ubuntu for profit, Canonical creates revenue by selling technical support. By keeping Ubuntu free and open source, Canonical is able to take advantage of the talents of outside developers in projects such as Linux, Debian, GNU, X.org, etc., without developing the entire operating system themselves.

Canonical endorses and provides support for four Ubuntu-based distributions: Kubuntu andXubuntu, which use KDE and Xfce, respectively, as a desktop environment, replacing the defaultGNOME system used by Ubuntu; Edubuntu, a subproject and add-on for Ubuntu, designed for school environments and home use; and Ubuntu JeOS (pronounced "Juice"), a stripped-down version of Ubuntu, optimized for virtual appliances.

Canonical releases new versions of Ubuntu every six months and supports Ubuntu for eighteen months by submitting security fixes, patches to critical bugs and including minor updates to programs. LTS (Long Term Support) releases, which occur every two years, are supported for three years on the desktop and five years for servers. The current version of Ubuntu, Intrepid Ibex, was released on October 30, 2008.

Ubuntu focuses on usability, including the widespread use of the sudo tool for administrative tasks. The Ubiquity installer allows installing Ubuntu to the hard disk from within the Live CD environment without the need for restarting the computer prior to installation. Ubuntu also emphasizes accessibility and internationalization, to reach as many people as possible. Beginning with 5.04, UTF-8 became the default character encoding, which allows for support of a variety of non-Roman scripts. The default appearance of the user interface in the current version is called Human and is characterized by shades of brown and orange.

The most recent version of Ubuntu comes installed with a wide range of software including the OpenOffice.orgproductivity suite, the internet browser Firefox, the instant messenger Pidgin (formerly known as Gaim), the BitTorrent client Transmission, and the raster graphics editor GIMP. Several lightweight card, puzzle, and board games are pre-installed, such as Sudoku and chess. Ubuntu has all networking ports closed by default for added security; its firewalloffers fine-grained control of incoming and outgoing connections. GNOME 2.22—the default desktop environment of Ubuntu 8.04—offers support for 46 languages. There are numerous ways to install Ubuntu, outlined below.