Money serves several functions that make it an essential part of modern economies. The main functions of money are:

1. Medium of exchange: Money acts as an intermediary between buyers and sellers, making transactions easier and more efficient. Without money, all transactions would have to be conducted by barter, which involves direct exchange of one good or service for another. This can be difficult because it requires a double coincidence of wants between two transacting parties.

2. Unit of account: Money serves as a common measure of value across the economy. It allows us to compare the value of different goods and services and make transactions more easily. For example, if you are shopping for a new computer, the price could be quoted in terms of t-shirts, bicycles, or corn. However, it is more helpful if the price is set in terms of money because it is a common measure of value across the economy.

3. Store of value: Money can be used to store wealth and can be easily retrieved and used at a later time. It is more liquid than most other stores of value because, as a medium of exchange, it is readily accepted everywhere. However, money may not be the best store of value because it depreciates with inflation.

4. Standard of deferred payment: Money must be acceptable to make purchases today that will be paid in the future. Loans and future agreements are stated in monetary terms, and the standard of deferred payment is what allows us to buy goods and services today and pay in the future.

In summary, money has three primary functions: store of value, unit of account, and medium of exchange. It also serves as a standard of deferred payment.