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Within the Installer you will find a wide collection of languages. The installer currently supports the following languages: Arabic, Bulgarian, Bengali, Czech, Danish, German, Greek, English, Spanish, Finnish, French, Hebrew, Devanagari(India), Croatian(Croatia), Magyar (Hungary), Italian, Malay, Norwegian bokmal, Dutch, Portuguese(Brasil), Portugues(Portugal), Romanian, Russian, Serbian, Svenska, Thai and more are being added all the time.
By default the English language is installed for the Back and Front-ends. You can download additional language files from the Joomla!Extensions Directory. In addition some translation teams are offering fully localised versions of the entire package. Please check the Joomla! Help Site for links to locations where languages and localised versions can be found.