No visa is required for EU member countries. A valid passport is required for most non-EU countries. It is, however, advisable to contact the German embassy or consulate in your country to enquire about entry formalities.

Practical information:

http://www.auswaertiges-amt.de/EN/EinreiseUndAufenthalt/Visabestimmungen_node.html

If you need an invitation letter for the embassy, please feel free to contact us.