The German currency is the Euro. Actually, the Euro is not "German money", but it is the currency we use in this country.
The Euro was introduced as cash currency in Germany on 1st January 2002, although it was used for cashless transactions by banks and stock markets in the eurozone since 1999. An Euro starter kit, to get people used to the new German currency, was released on 17th December 2001.
Euro banknotes are issued in €500, €200, €100, €50, €20, €10, €5 notes.
Denominations of Euro coins are €2, €1, 50c, 20c, 10c, 5c, 2c, and 1c.
All Euro coins have a common side showing their value, while the national side shows an image chosen by each country.
Euro coins from any member state are valid in all states throughout the Euro zone.
The Euro notes, front and back side, are the same in all countries.
There's no doubt, you need money when you travel around Germany! :)
For visitors from outside the Euro zone the below online currency converter tool is handy to check how many Euro you get for your local currency.
Credit cards are widely accepted, although paying with credit cards is not as common as in the USA, for example. Mastercard & Visa dominate. American Express & Diners Club are accepted in some stores and of course you can use them with the Geldautomat. Check shop windows and entrance doors for credit card logos to see which cards you can use inside.
Supermarkets, department stores and restaurants, especially in smaller towns outside tourist regions, might only accept a German bank card, or cash. You will definitely have to pay cash at many locations in Germany.