Anyone who moves to or within Germany should register their name and residential address at the Residents’ Registration Office ("Einwohnermeldeamt", "Bürgeramt" or "Bürgerbüro") within two weeks at the latest. If you don't register or do it too late, you might have to pay a fine. When you register you will receive an Official Registration Confirmation ("Amtliche Meldebestätigung"). Keep this paper in a safe place. This enables you to prove - even without your ID - that you are registered in a municipality or city in Germany, i.e. you reside there.