Today money is generally accepted as payment for goods and services or repayment of debt. But governments still fret about whether there's too much (or too little) in circulation, economists can't agree on what it is, and the enduring popularity of alternative or crypto-currencies shows rumbling discontent with the official version. These 10 short animations chart the evolution of money from stones and whale teeth to modern monetary policy and banking, and takes a hard look at money's role in economic crises.