The number of the Ubuntu release is 'X.YY', with 'X' being the year of release (minus 2000) and 'Y' being the month of release. For example, Ubuntu 4.10 was released in October (the tenth month of the year), 2004. The name of the release (for example, Breezy Badger) is an adjective (a describing word) followed by the name of an animal.