What's the meaning of version numbering of ubuntu?

Question

What's the meaning of the numbering for different versions? Do they signify something?  

Answer 1

Ubuntu follows a regular 6 month release cycle. The version numbers are formatted in Y.MM (10.04: April, 2010). Every two years there is a Long Term Support (LTS) version release which will be officially supported for two more years.

The last LTS was 8.04, the current LTS is 10.04, and the next LTS is 12.04 - the three releases between these LTS releases culminate into the next LTS, ideally viewed as "6-month baby releases piecemealing towards the next LTS".

Typically after each non-LTS release a point release is made for the current LTS designed to maintain stability and backport changes keeping an LTS release 'supported' These are denoted as a third version number (10.04.[1-4]).

This chart and more information can be found on the Ubuntu Wiki: LTS article.

Answer 2

Yes. The first number is the year the distribution was released (so 09 means 2009, obviously), and the second number is the month it was released. Therefore, the upcoming 10.10 version will be released in October 2010.

Answer 3

Additionally they also have code names usually some sort of adjective and an animal name here is a list of all the Ubuntu versions including the next one.

Version    Name             Release Date  
4.10       Warty Warthog    2004-10-20
5.04       Hoary Hedgehog   2005-04-08
5.10       Breezy Badger    2005-10-13
6.06LTS    Dapper Drake     2006-06-01
6.10       Edgy Eft         2006-10-26
7.04       Feisty Fawn      2007-04-19
7.10       Gutsy Gibbon     2007-10-18
8.04LTS    Hardy Heron      2008-04-24
8.10       Intrepid Ibex    2008-10-30
9.04       Jaunty Jackalope 2009-04-23
9.10       Karmic Koala     2009-10-29
10.04LTS   Lucid Lynx       2010-04-29
10.10      Maverick Meerkat 2010-10-10
11.04      Natty Narwhal    2011-04-28
11.10      Oneiric Ocelot   2011-10-13
12.04LTS   Precise Pangolin 2012-04-26

Answer 4

...and don't forget the upcoming Point-Release 10.04.1 which summarize all the updates (and bugfixings) since the Release-Day. So you don't have to patch a new installed system with hundreds of MBytes. On August 12 2010 the 10.04.1 will be available.

Answer 5

Apart from the points mentioned in other answers, there are few more things to add:

• Starting with Ubuntu 12.04 LTS, LTS releases will be supported for 5 years on both the desktop and the server. Previous Ubuntu LTS (Long Term Support) releases are supported for 3 years on the desktop and 5 years on the server.
• Each Ubuntu version has a fancy animal name, along with an adjective. Apart from those listed above, we have few more.

Adjective        Animal         Version   
Quantal          Quetzal        12.10
Raring           Ringtail       13.04

• Quick references:
  • Ubuntu Releases
  • Release Schedule
  • DevelopmentCodeNames
  • LTS