Money is not only coins and banknotes, It is anything that people are willing to use in order to represent the value of other things for the purpose of exchanging goods and services. Money enables people to compare quickly and easily the value of different commodities (such as fish and shoes), to exchange one thing for another, and to store wealth conveniently. There have been many types of money. The most familiar is the coin, which is a standardized piece of imprinted metal. Yet money existed long before the invention of coins, and cultures have prospered using things as currency, such as cowries, cattle, skins, salt, grains, beads, cloth and promissory notes. In modern prisons, cigarettes have often served as money. Nowadays people do not have to carry money when they go for shopping, the can use debit or cash cards. These cards are also called plastic money.