Notgeld (German for Emergency Money), was special money issued in Germany and Austria to deal with the inflation caused by the cost of World War I. The value of metal used for coins became higher than the coins denomination, and paper money was issued to replace the coins. Notgeld were issued by cities, private firms and municipalities and varied extremely from place to place. After 1922 German economy spiraled into a hyperinflation, and currency denominations sky-rocketed—there was a 50-million banknote issued. Read more about it at wikipedia.