Ubuntu is a linux distribution. It is based on Debian and composed mostly of free and open-source software. Ubuntu is released every six months, with long-term support (LTS) releases every two years. Ubuntu is developed by British company Canonical. Canonical provides security updates and support for each Ubuntu release, starting from the release date and until the release reaches its designated end-of-life. Canonical generates revenue through the sale of premium services related to Ubuntu and donations from those who download the Ubuntu software.
Current long-term support (LTS) releases are supported for five years, and are released every two years. Since the release of Ubuntu 6.06, every fourth release receives long-term support. The first LTS releases were supported for three years on the desktop and five years on the server; since Ubuntu 12.04 LTS, desktop support for LTS releases was increased to five years as well.
Ubuntu packages are based on packages from Debian's unstable branch, which are synchronised every six months. Both distributions use Debian's deb package format and package management tools. Debian and Ubuntu packages are not necessarily binary compatible with each other, however, so packages may need to be rebuilt from source to be used in Ubuntu.
Although Ubuntu is a distribution built on Debian, there are distributions that use Ubuntu as a base such as Kubuntu and Mint as two examples. Our Kubuntu and Ubuntu Linux Distribution Reference offers a comparison of features and configuration tips for each. Our popular Mint Linux Distribution Reference focuses on Mint as an alternative to Ubuntu which is highly recommended.