Here are some photos of America currency: among the coins there are dimes, quarter dollars and pennies. Each country has its own currency; after the constitution of the European Union the member states can use the same currency called euro. Before the introduction of money people used to exchange goods with the technique of swap. Credit cards, invented in the USA in the 1950, offer a new kind of money transaction; credit card holders are able, for example, to balance their debt at the end of each month. Credit cards also allow to pay online, for example from ebay.
photo -> object -> money