Ubuntu releases are made semiannually by Canonical Ltd, the developers of the Ubuntu operating system, 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 20 October 2004. Consequently, version numbers for future versions are provisional; if the release is delayed until a different month (or even year) to that planned, the version number will change accordingly.
Canonical schedules Ubuntu releases to occur approximately one month after GNOME releases, which in turn come about one month after releases of X.Org, resulting in each Ubuntu release including a newer version of GNOME and X.
Every fourth release, occurring in the second quarter of even-numbered years, has been designated as a long-term support (LTS) release. The desktop version of LTS releases for 10.04 and earlier were supported for three years, with server version support for five years. LTS releases 12.04 and newer are freely supported for five years. Through the ESM paid option, support can be extended even longer, up to a total of ten years for 18.04. The support period for non-LTS releases is 9 months. Prior to 13.04, it had been 18 months.
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