Joomla and languages/translations
From Joomla! Documentation
Joomla! speaks many languages.
There are quite a few options and strategies available to making Joomla! speak your language. This page will help describe the options and point you in the right direction.
Since Joomla! 1.5 all user interfaces can be localised. This includes the installation, the administrator interface and the front end site.
The core release of Joomla! 1.5 is shipped with multiple language choices in the installation but languages for the site and administration interfaces need to be added after installation. (Other than English). Links to such language packs exist below.
Translation Teams for Joomla! 1.5 may have also released fully localised installation packages where site, administrator and sample data are in the local language. These localised releases can be found in the specific team projects on the Joomla! Forge.
Joomla 1.6 
Starting with Joomla 1.6 it is also possible to have the site in multiple languages for your visitors to choose from. To enable this functionality you need to enabled the languageswitche module and the languageswitcher plug-in.
Accredited language packs
- The Translations Working Group maintains a repository of accredited language packs:
