In a perfect economy the price mechanism can provide a perfect allocation of resources: what is demanded is produced, changes in demand lead to changes in supply, and workers move from a dying market to a growing one. Unfortunately, the economy is not perfect. To stop arriving at this splendid market solution. Only one of these elements is needed to be operational and the perfect market solution above will fail. In a world where most products are scarce and people's desires are unlimited, the allocation of resources is the main concern of the economy. The obvious starting point for analyzing this basic problem is price and its important functions for coordinating the decisions of buyers and sellers in a market economy. The price mechanism, or more known as the "invisible hand", performs three important functions in any market-based economy. : rationing, reporting and incentive. Prices serve to ration scarce resources in situations where demand exceeds supply. Where there is a shortage of products, prices rise. Therefore, assisted people with sufficient willingness to pay will do so ...