Throughout history, a wide variety of items have served as money. These include gold, silver, large stone wheels, tobacco, beer, dog teeth, porpoise teeth, cattle, metal coins, paper bills, and checks. All of these types of money should be judged on how well they accomplish the functions of money. Money is what money does. To be a good medium of exchange, money must be accepted by people when buying and selling their productive resources and when buying and selling goods and services. It should be portable or easily carried from place to place. It also must be divisible so that large and small transactions can be made. To be a good store of value, money must be durable so it can be kept for future use. It also should have a stable value so people do not lose purchasing power if they use the money at a later time. To be a good standard of value or unit of account, money must be useful for quoting prices. To accomplish this, money must be familiar, divisible, and acceptable.