Nope! That's a valid and important question. Although what I'll tell you is not an official answer, just my personal knowledge and opinion about it
Originally Posted by d1lu5ion
Also, I have a very bad habit of pouring everything I know if a poor innocent user makes the mistake of expressing curiosity about something I know (or I believe I know). So get prepared to suffer the punishment below -
LTS (Long Term Support) Release
Think of an LTS, like 12.04 as an enterprise release. It is supposed to be stable and supported for a long time, while containing everything that can be offered without compromising the stability. It comes out with only those features that have been tested thoroughly and are supposed to be bug-free, stable and working for most, if not all, users.
Further, its updates (the default, recommended ones) contain only those things that have also been tested enough and are supposed to be stable. Of course no software is 100% bug free and this is especially true in active Open-Source projects like Ubuntu. So despite a lot of care, bugs do keep appearing from time-to-time, but a lot less in numbers in an LTS, and (I assume) are paid more attention thus getting fixed relatively quicker.
It is released every 2 years in April (thus always a ".04" version like 12.04, 10.04, 8.04...). Before 12.04, only the server version of the LTS was supported for 5 years, while the desktop for only 3 years. From 12.04 (and onwards), it was decided that both desktop and server versions will be supported for 5 years.
There are also "Point-releases" of LTS versions, which are nothing but a release of LTS including the latest official updates (including newer kernel and software packages that have been officially released in its updates). These are represented by an additional number in the last (.1, .2, etc.), like the current "Point-Release" of 12.04 LTS is 12.04.2.
It means that when you install a point release (the default ISO available at official download links), you are getting a version that already contains the updates that have been released since the original release till the date of the release of that Point-Release.
The next LTS will be 14.04, releasing in April 2014.
Think of them as relatively more liberal, more trendy, sort of 'Enthusiast' releases (my personal views, hope I'm not offending anyone). It contains features and support that could not be included in the LTS because of some reasons. Some of these reasons can be -
* Maybe the feature/suport was not ready at the time of the release of the LTS
* Maybe it wasn't tested enough
* Maybe it was too buggy
* Maybe there were questions about its usability or whether the users would like it or not...
These "Standard Releases" serve two main purposes -
1) For users it serves as a release that lets them enjoy the latest, latest trends and cutting edge features/technology.
2) For developers it serves the purpose of extensive mass-testing of features that they intend to include in the next LTS.
The standard releases are released every 6 months (in April and October every year, thus the version numbers always being ".04" and ".10"). Before 13.04, the standard releases were supported for 18 months. Which meant there used to be times when the developers had to support 10-11 different versions simultaneously (for example, in April 2010). With the decision to extend the desktop LTS support to 5 years like the server version, this was going to get worse. This brings us to the answer to your original question -
Why is Standard Release Support Period is Short ?
Supporting a release means keeping it up-to-date with latest security patches, latest bug-fixes, updating hardware-support, etc. and doing all this while trying not to break an existing feature/package. This requires a lot of care and work from the developers. Since supporting the LTS is a serious commitment, it is difficult for the developers to support multiple distros simultaneously.
From 12.04, Canonical decided to get more aggressive on development front, while also hardening stability on the LTS front. So it shortened the support period of the Standard Release to just 9 months. With this change, now there will be at most 8 different versions to support at a given time (including server versions).
(just calculated, can be wrong)
Keeping the "Standard Release" support period short allows the developers to move on to a newer release that contains most of the features that were tested ok in the previous one, replacing or dropping altogether the features that were too problematic, and include the latest ones on a whole new build. Thus -
* The developers don't have to carry the burden of supporting too many different versions with the same purpose. Features that have been proven stable and useful can be moved to the existing LTS in the form of updates, or marked for inclusion in the next LTS.
* They can keep testing the existing not-yet-stable-enough and newer features in the next Standard Release.
* The users who like to enjoy the latest features can move on to the next release (be it LTS or a standard one, whatever is latest)
* The users who prefer stability can stick with the LTS, until the next one comes out.
That's all of my personal understanding of the reasons why the standard releases have a short support duration (of course based on many articles/discussions I have read, but can't call them as 'Authoritative' statements).
Some useful links elaborating these facts/differences :