Ubuntu

Ubuntu is a distribution of Linux that was started in 2004 by Canonical Ltd. Unlike many other Linux distributions, Ubuntu is designed for use as a desktop OS and currently owns the third largest market share on operating systems.

The Ubuntu system is built on the Debian infrastructure.

Versioning
Ubuntu uses a date-based version scheme, where the major version is the year of release, and the minor version is the month padded by a zero if necessary. Each version also has a codename consisting of an adjective and animal name both starting with the same letter, which since Ubuntu 6.06 follows alphabetical order.

Two Ubuntu versions are released each year, one in each half of the year (usually in April and October). The first release in even years is an LTS release supported for 5 years, which can then be extended for additional 10 years via the paid Extended Security Maintenance program. Other releases are referred to as Interim releases, and are only supported for 9 months, after which it is recommended to upgrade to a newer version.

Flavors
The standard Ubuntu desktop uses GNOME; however, there are alternative variants called flavors, which are optimized for different desktop environments or use cases. Unlike regular derivatives, Ubuntu flavors are officially recognized by Canonical, make use of some of its infrastructure and notably use Ubuntu package repositories only, with no custom repositories.