What are the main functions of money?

1. It is a medium of exchange: like the rancher "trading" money for a new fence, money is used to buy and sell things. Without money, we would be bogged down in a system of barter. 

2. It is a store of value: pity the rancher whose cow gets sick on Monday and who wants to buy some clothes on the following Saturday, by which time the cow may have died and lost its value. In the form of currency, however, money can be used for future purchases and therefore "stores" value.

3. It is measure of worth: Money lets use measure the relative values of goods and services. It acts as a measure of worth because all products can be valued and accounted for in terms of money.