Barter is a method of exchange by which goods or services are directly exchanged for other goods or services without using a medium of exchange, such as money. It is usually bilateral, but may be multilateral, and usually exists parallel to monetary systems in most developed countries, though to a...
, most markets rely on sellers offering their goods or services (including labor) in exchange for money
Money is any object or record that is generally accepted as payment for goods and services and repayment of debts in a given country or socio-economic context. The main functions of money are distinguished as: a medium of exchange; a unit of account; a store of value; and, occasionally in the past,...
from buyers. It can be said that a market is the process in which the prices of goods and services are established.
For a market to be competitive, there must be more than a single buyer or seller.