During and after the first World War few countries in Europe had any silver or gold to back their coinage, nor enough of the normal coinage metals, including copper and nickel, with which to make coins. Their economies had been severely strained by the direction of all available funds to the war effort. Germany had been hit particularly hard. Not only were the results of its expenditures lost in failed objectives and spent materiel, not only was it faced with ruined infrastructure, but it was also required, as the loser, to pay enormous punitive reparations to the winners of the conflict.
Needing to continue somehow with their daily economy, Germany began to issue money without backing (the only kind of money kind of money in use anywhere today). The physical form taken by this money was primarily paper. Since the national issues were in short supply local governments undertook to make up some of the lack, and issued their own "notgeld," or "emergency money."
At first (1914-15) this money was quite plain, with a simple seal of the issuing authority, and signed by some local notable. But by 1920 towns, villages, and even businesses had begun to issue whole series of notes in brilliant colors to take the place of the coinage they lacked. The more attractive they could make these notes, the better the chance that people using them would keep them rather than turning them in for redemption in 6 months or a year, the promise of which was made on most of the notes. If people collected the notes the town would be able to keep the entire value of the notes, rather than just obtaining the increase in commerce consequent on their circulation.
These "series" notes evolved to depict local historical events and figures, tourism sites, fairy tales, to promote political views, to exhibit poetry, sometimes humorous and other times foreboding, often in local dialect as well. If a poem or story was spread over several notes one had to get, and hopefully keep, all of the notes of that series.
By 1922 inflation was already gnawing at the heart of the German economy, and the 1, 2, 5, 10, 25, and 50 pfennig notes of 1920-21 had become worthless. New notes were printed in higher values. The faster the rate of inflation became the more quickly the new notes had to be printed, and at ever higher denominations. So the colorful lighthearted notes disappeared, replaced by increasingly plainer 100 mark, 1000 mark, and eventually billion mark notes (note that English "billion" is German "milliarde," and German "billion" is English "trillion").
While it is true that other European countries issued their own emergency money too, it was Germany, in the brief period between 1920 and 1921, that printed by far the most varied and interesting notes. Germans began to collect these later in the 1920s, and now the notgeld is being rediscovered all over the world for the cultural interest, instruction and beauty it has to offer. Notgeld, as a collectible class, remains quite affordable at present, availing us all of access to a truly fantastic era in the history of currency, and of a people.