The market is the most simply defined place where supply and demand are meeting, and money is exchanged through money and services. As such, it can be defined in competition through duopoly, oligopoly, monopoly and incomplete competition. The market has different functions, and the most basic ones are: information function, selective function, allocative function and distributive function. Each of these functions are important for work and success of the market itself. After the market, we come to the concept of market competition, which is shared with perfect and imperfect. A perfectly competitive market, is a market where all companies are producing identical products, and each company is so small that its production-level selection does not affect the entire industry. Entering in sucha market is easy, if there is a chance to make a profit. Product homogeneity, free entry and exit and pricing are the main characteristics of the market in perfect competition. Unfinished competition is such a market situatio, in which there is one or more entities that can influence the formation of prices and quantities offered or sought. The markets of imperfect competition are oligopoly, duopoly and monopoly. Each of these markets of imperfect competition are specific in their own way. Monopoly is a form of imperfect competition where the entire offer is controlled by only one company. It occurs in the production of those goods and services that do not have their substitutes. Oligopoly is the typical and most common form of monopoly structure. It once belongs to the limited and the second time to monopolistic competition. Typically an oligopoly market is the car market. Duopol is a form of imperfect competition where the entire supply is controlled by two companies. They are showing in those business branches where entering is very hard for competitors. The duopoly products may be homogeneous but also differentiated. When we talk about examples in the Republic of Croatia, the best example of monopoly is HEP - Croatian Electric Industry, and the best example of the oligopoly is Croatian telecommunications. Car industry is the best display of the monopolistic competition, while the wheat and maize market is the best display of perfect competition, which is very rare in Croatia.