Each of our extensions has a Version History page where you can see exactly what has changed in each version. Our Components have an About page, where you will find the version number of the version you are running, and a link to the relevant Version History page.
We don't like the idea of blindly installing updates just because a new version is available. If a new version has a fix or a new feature that you need, then install it. If not, there is no need.
In an ideal world, you should test all new versions of software on a test site before installing them on your live site. In practice, of course, many people don't do this, so we have adopted this policy: For minor version changes (like 5.09 to 5.10) it's likely that you can update without encountering any issues or significant changes to the front end of your site. Major version changes (like 5.10 to 6.00) can affect the appearance or functionality of the front end, so you should check the documentation for the new version, and consider installing it on a test site first.
We use the standard GNU version numbering scheme, major.minor.revision:
XX is the major version number. This is incremented when there is impact to the front end, there are major code changes, major new functionality is added, or the upgrade requires additional work on your part. When you upgrade an extension to a new major version, we recommend that you install it on a test site and check it before you install it on your live site. If you have customised the product CSS, you may have to re-implement your changes on the new version as the CSS class names and HTML structure might have changed.
YY is the minor version number. This is incremented for bug fixes, new functionality, and new language translations. You should be able to implement these straight onto your live site, although you should be able to reverse the upgrade if necessary.
ZZ is the revision number. This is incremented for minor cosmetic fixes, translation corrections, or minor bug fixes. These changes do not trigger a Joomla update notification and are not shown in our published version histories. You don't need these upgrades unless we specifically advise you to install them.