This site is where you can find the official documentation developed and maintained by the Ubuntu Documentation Project.
Choose your version of Ubuntu below to access the documentation for that version. If you don't find what you are looking for, visit the community contributed documentation for even more material!
Ubuntu 8.10 - the current stable version, released in October 2008, codenamed Intrepid Ibex.
Ubuntu 8.04 LTS - the current long term support version, released in April 2008, codenamed Hardy Heron.
Ubuntu 7.10 - previous stable version, released in October 2007, codenamed Gutsy Gibbon.
Ubuntu 6.06 LTS - previous long term support version, released in June 2006, codenamed Dapper Drake.