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.

Timeline
Ubuntu is versioned differently to other software, with the major version indicating the year of release and minor version indicating month. The first version was 4.10 (October 2004).

Ubuntu versions are named after various different adjectives and animals in alphabetical order (the alphabetical naming scheme starting with Ubuntu 6.06 LTS), similar to how versions of Debian are named after various Toy Story characters. Versions of Ubuntu usually release on April and October.

The version type varies depending on the month it was released. Versions released on April are sometimes LTS (Long Term Support), while October releases are always interim releases.

LTS releases get supported by 5 years, and can be extended for a decade via the paid ESM (Extended Security Maintenance) program. Interim releases last only 9 months, and it is recommended to upgrade to a newer or a LTS release once support for a specific version ends.