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Ubuntu, an operating system based on Debian GNU/Linux, makes two releases every year, using the year and month of the release as a version number. The first Ubuntu release, for example, was Ubuntu 4.10 and was released on October 20, 2004. Consequently, version numbers for future versions are provisional; if the release is delayed until a different month to that planned, the version number changes accordingly.

Ubuntu releases are also given code names, using an adjective and an animal with the same first letter (e.g. Dapper Drake). With the exception of the first two releases, code names are in alphabetical order, allowing a quick determination of which release is newer. Commonly, Ubuntu releases are referred to using only the adjective portion of the code name (e.g. Dapper).

Releases are timed to be approximately one month after GNOME releases, which are in turn about one month after releases of X.org. Consequently, every Ubuntu release comes with a newer version of both GNOME and X. Releases 6.06 and 8.04 have been labelled as a Long Term Support (LTS) to indicate support with updates for three years on the desktop and five years on the server, with paid technical support available from Canonical Ltd.