During the last couple of years, the Production Leadership Team (PLT) has churned out quite a few versions of Joomla. This is great, but it leaves some users confused as to how to approach all these versions.
If you are one of them, reading this post will help you understand how the different versions of Joomla follow each other. And how to upgrade or migrate from each one.
Change in numbering convention
During fall 2011 it was decided to change the numbering of Joomla versions. The next major version of Joomla is going to be numbered 2.5. The explanation is that 2.5 will be the next Long Term Support release of Joomla, with a support time of at least 1,5 years. 2.5 will be followed by 2.6, 2.7 etc, until the PLT decides to release another Long Term Support release (3.5). You can think it is a wise decision or not, but that's how it's going to be.
Joomla 1.5
Joomla 1.5 is the current Long Term Support (LTS) release.
Most of the Joomla sites out there are still on this version. The reason for this can be that the changes made from 1.5 to 1.6 are quite significant. It involves migrating your site with the jUpgrade tool. You also have to make sure that your templates and installed extensions are available in a version that supports the changes in 1.6 and later versions.
Upgrading from 1.5
If you have a Joomla 1.5 site, you should use jUpgrade to migrate to the latest stable version of Joomla (currently 1.7).
Joomla 1.6
1.6 introduced a lot of new features, like ACL and nested categories.
For this reason, the Joomla project decided to keep 1.5 around for quite a while (1.5 years) to support all the sites already built with that technology.
Joomla 1.6 was a short term support release that was replaced by 1.7. Joomla 1.6 should not be used anymore, as 1.7 took over at the time of release.
Upgrading from 1.6
If you have a 1.6 site, you should move to 1.7 as soon as possible and then to 2.5 (when it's stable). Upgrading from 1.6.4 to 1.7 is a one-click upgrade in the Joomla admin.
Joomla 1.7
Joomla 1.7 was another short term support release. The version has improvements over 1.6, but it is still using mostly the same architecture and data model as 1.6.
1.7 is soon being replaced by 2.5, which is also a Long Term Release like 1.5.
Upgrading from 1.7
If you have a 1.7 site, you should upgrade to 1.7.3, and then to 2.5 (when it's stable). Upgrading to 2.5 from 1.7.3 will be a one-click update in the Joomla admin.
Joomla 2.5
Version 2.5 will be the next Long Term Support release of Joomla. At the moment, the first beta version of 2.5 has been released. It should not be used for production sites, but testing is encouraged to help fix bugs.
Stable version of 2.5?
Clipped from joomla.org:
Joomla 2.5.0 GA (general availability) is due to be released on or about 10 January 2012. The planned milestone after this date are:
- 10 February 2012 - Joomla 1.7 reaches end of life and is no longer supported
- April 2012 - Joomla 1.5 reaches end of life
- July 2012 - Next version of Joomla is released
Please note that dates may be subject to change depending on availability of volunteers and circumstances beyond our control.
The Joomla platform
In 2011, the PLT decided to separate the Joomla Platform from the CMS. What this means can be read about in my post What is the Joomla platform and why should you care.
The Joomla platform has it's own numbering convention (starting on version 11). For most end-users, this will mean absolutely nothing, as the Joomla platform is included in the Joomla packages.
Still confused?
If you're still confused, this excellent infographic made by Sander Potjer can be helpful in understanding how the development strategy works.
 has churned out quite a few versions of Joomla. This is great, but it leaves some users confused as to how to approach all these versions.
If you are one of them, reading this post will help you understand how the different versions of Joomla follow each other. And how to upgrade or migrate from each one.
){kind=link}