The market is known as “a group of buyers and sellers of a particular good or service” (Mankiw, 2012, p. 66). Everyone interacts with each other in a market in daily life. Generally, markets can be classified into four types: perfect competition, monopoly, monopolistic competition and oligopoly. The first type of competitive market is perfect competition. Perfect competition has three characteristics. First, it must have “many buyers and sellers in the market, [firms that] can freely enter or exit the market, and each [firm] selling an identical product, so each buyer and seller are price buyers” (Mankiw, 2012 , page 280). For example, in the egg market there are many sellers and buyers, so sellers have no market power to influence the selling price and therefore have to follow the market price. Furthermore, in perfectly competitive markets, the firm's decisions can be classified into short-run decisions and long-run decisions. The short run is defined as a period of time in which each firm has a certain plant size and the number of firms in the industry is fixed; while the long run is defined as a period of time in which the quantities of all inputs can be varied. In the short run, the firm can decide whether it wants to continue producing or close the industry and the quantity to produce if it decides to produce. In the long run, firms may choose to enter or exit the industry, resulting in an increase or decrease in plant size. The advantage of a perfectly competitive market is that it is easy to enter or exit the industry and that consumers can purchase an identical product at a fair market price; while the disadvantage is that sellers cannot increase the selling price as they wish. Profit-maximizing production is the… center of the paper… consumers can plan and balance their expenses. This is because the oligopolistic market has stable prices (Sonkushre, 2012). An oligopolistic market scam is facing the problem of cheating. According to Arnold (2008), some oligopolistic firms collude with each other to reduce the quantity of product and increase the demand for product. Another disadvantage of the oligopolistic market is the high barrier to enter and exit the market (Arnold, 2008). It provides difficulty for new businesses to enter the market. In conclusion, there are four main types of market structure in the economy which are perfect competition, monopolistic, oligopoly and monopoly. They differ in the number of sellers and buyers, short- and long-term profits, and barriers to entry. No market structure is better than another as they all have their pros and cons. Some can benefit consumers in ways that others cannot.