The concept of a consumer is used in different contexts, so that the usage and significance of the term may vary. Whatever context is chosen, in order to maintain the balance on the markets consumers have to be satisfied. Consumers are the moving force of every market. They determine what product is to be manufactured, set the demand on this or that type of goods, define the trends in the sphere, as well as cause the changes on the market. Consumers are people who accept the manufactured goods in exchange for something worthy, at the present time, - for the money. At the very beginning, barter defined people as consumers and retailers. Later on the system developed and the distinction between former and later became more obvious. Today, in the world of incredible competition consumers are kept satisfied. A retailer who loses its client will not survive. That is why consumers are like warning signs. If the quality of goods and services worsens, the warning signs come in form of complaints and negative feedbacks.