Money is used for buying or selling goods, for measuring value and for storing wealth. Almost every country now has a money economy based on coins and paper notes of one kind or another. However this has not always been true. In primitive societies a system of barter was used. Barter was a system of direct exchange of goods. Somebody could exchange a sheep, for example, for anything in the market place that they considered to be of equal value. Barter, however, was a very unsatisfactory system because people’s precise needs seldom coincided. People needed a more practical system of exchange, and various money systems developed based on goods, which the members of a society recognized as having value. Cattle, grain, teeth, shells, feathers, skulls, salt, elephant tasks and tobacco have all been used. Precious metals gradually took over because, when made into coins, they were portable, durable, recognizable and divisible into larger or smaller units of value.
A coin is a piece of metal, usually disk shaped, which bears lettering, designs or numbers showing its value. Until 18th century coins were given monetary worth based on the exact amount of metal contained in them, but most modern coins are based on face value, the value that governments choose to give them, irrespective of the actual metal content. Coins have been made of gold, silver, copper, aluminum, nickel, lead, zinc, plastic, and in China even from pressed tealeaves. Most governments now issue paper money in the form of notes, which are really promises to pay. Paper money is obviously easier to handle and much more convenient in the modern world. Cheques, bankers’ cards, and credit cards are being used increasingly and it is possible to imagine a world were money in the form of coins and paper currency will no longer be used. Even today, the USA, many places – especially filling stations – will not accept cash at night for security reasons.