Normally, you should use the latest version of Joomla! for a new site unless you have a specific reason not to. The latest version can be downloaded from the Joomla! download site.
- Make sure that you subscribe to the Joomla! Security Announcements feed. This forum is used to make announcements, including the availability of new releases, that could affect the security of your site.
- Check for the latest version. If you are not on the latest release, read the release notes to see if you need to upgrade. If a release is being made in order to address security issues then it is strongly advised that you upgrade as soon as possible. You can see the release history of each series here:
- If you are running an earlier release of the current version (for example, you are running 2.5.1 and the current version is 2.5.6), you should upgrade to the current version. Each minor release fixes a number of bugs and/or security issues. It is always good practice to upgrade to the latest minor version as a first step in troubleshooting a problem and fixing any newly discovered security issues.
Many Joomla! Extensions have been released for version 2.5, with more being offered each week. Generally, any extension created for 1.6 and 1.7 will work on a Joomla! version 2.5 installation. There may be specific cases where an Extension is available for version 1.5 and not available for versions 1.7 or 2.5. This could be a reason to continue using Joomla! version 1.5.