There is a Stack Exchange site dedicated to Ubuntu, which is also a good place to ask any Ubuntu-related questions if you can't find an answer on Super User.
The name "Ubuntu" has ancient African philosophical roots and means 'humanity to others'. It also means 'I am what I am because of who we all are'.
The Ubuntu operating system brings the spirit of Ubuntu to the world of computers.
Each version of Ubuntu has a code name, consisting of an alliterating adjective and animal name. A complete, up-to-date list of the releases is available here.
New versions are released every 6 months while LTS (Long Term Support) releases, which are meant to be more stable for people who are unable (or unwilling) to upgrade every 6 months, are released every 2 years. LTS releases are timed to occur at the same time as an ordinary stable release would happen, but the LTS development cycle typically involves more conservative feature scoping and more rigorous testing to ensure a stable and fully functional release that can be supported for a long period of time.
The Development Version
The development version of Ubuntu is not recommended for beginners because it often contains major bugs and incomplete functionality. The release currently in development is ubuntu-15.04 (Vivid Vervet). Alpha, Beta, and Release Candidates of each development version are released for testing purposes starting about two months (one-third) of the way into the development cycle, as defined by the Release Schedule.
The release schedule of the current development version, Utopic Unicorn, can be found here.
At any given time, two or three LTS versions are supported as well as the most recent prior non-LTS version. If the latest stable release is non-LTS, then two non-LTS releases are supported: the current and the prior one. If the latest stable release is an LTS, then only the prior non-LTS release and the LTS releases are supported.
Support means that security and bug fix updates are continuing to be released to the update repositories. When support is dropped for an old release, responsibility for fixing any bugs or security issues is left up to the user.
The released, currently supported desktop versions are:
- ubuntu-14.04 (Trusty Tahr) Current LTS Version
- ubuntu-13.10 (Saucy Salamander) Current Stable Version
- ubuntu-12.10 (Quantal Quetzal) Prior Non-LTS Stable Version
- ubuntu-12.04 (Precise Pangolin) Prior LTS Version