An oligopoly is an intermediate market structure between the extremes of perfect competition and monopoly. Oligopoly firms might compete (noncooperative oligopoly) or cooperate (cooperative oligopoly) in the marketplace. Whereas firms in an oligopoly are price makers, their control over the price is determined by the level of coordination among them. The distinguishing characteristic of an oligopoly is that there are a few mutually interdependent firms that produce either identical products (homogeneous oligopoly) or heterogeneous products (differentiated oligopoly) (Rajeev K. Goel, 2014, P183) There are two main characteristics of oligopoly, including small number of firms and interdependence. There are only a few manufacturers in the industry. There is no difference in the products. And there is a considerable degree of control over the prices. Then it is quite difficult to enter and leave the industry. For example, the automotive industry, electrical equipment industry, and canning industry in the United States are controlled by several companies.

The appearance of the oligopolistic market is mainly attributed to three reasons. First, due to the economies of scale, that is, manufacturers continue to expand production scale, and the market is relatively small. The second reason is due to the barriers to entry. The government grants monopoly power to certain enterprises in the industry through laws and regulations, and at the same time, it imposes certain controls on it