Ubuntu utilizes two-word codenames in the development of future releases of the Linux-based operating system. While the official Ubuntu releases carry a version number in the form of X.YY, with the "X" representing the year and the "YY" signifying the month of the official release, the Ubuntu codenames use an "adjective animal" combination, or an adjective word followed by the name of an animal, typically one that's unique or not all that well known.
The Ubuntu codenames are always alliterations, and they have generally ascended in alphabetical order with each successive release, although not always with the next letter in the alphabet used. The quirky codename game started with development of the v4.10 release of Ubuntu in 2004 under the codename of Warty Warthog. Hoary Hedgehog (v5.04) followed in April 2005, Breezy Badger (v5.10) in October 2005 and Dapper Drake (v6.06) in June 2006.
Dapper Drake started the process of new Ubuntu codenames ascending in alphabetical order. Since Dapper Drake, Ubuntu codenames have been Edgy Eft (v6.10), Feisty Fawn (v7.04), Gutsy Gibbon (v7.10), Hardy Heron (v8.04), Intrepid Ibex (v8.10), Jaunty Jackalope (v9.04), Karmic Koala (v9.10), Lucid Lynx (v10.04), Maverick Meerkat (v10.10), Natty Narwhal (v11.04), Oneiric Ocelot (v11.10), Precise Pangolin (v12.04) and Quantal Quetzal (v12.10).