In economics, imperfect competition refers to a situation where the characteristics of an economic market do not fulfil all the necessary conditions of a perfectly competitive market. Imperfect competition causes market inefficiencies, resulting in market failure. Imperfect competition usually describes behaviour of suppliers in a market, such that the level of competition between sellers is below the level of competition in perfectly competitive market conditions.

An oligopoly is a market in which control over an industry lies in the hands of a few large sellers who own a dominant share of the market. Oligopolistic markets have homogenous products, few market participants, and inelastic demand for the products in those industries. As a result of their significant market power, firms in oligopolistic markets can influence prices through manipulating the supply function. Firms in an oligopoly are also mutually interdependent, as any action by one firm is expected to affect other firms in the market and evoke a reaction or consequential action. As a result, firms in oligopolistic markets often resort to collusion as means of maximising profits.