Imperfect competition refers to any economic market that does not meet the rigorous assumptions of a hypothetical perfectly competitive market.
In this environment, companies sell different products and services, set their own individual prices, compete for market share, and are often protected by entry and exit barriers.
Imperfect competition is common and can be found in the following types of market structures: monopolies, oligopolies, monopolistic competition, monopsony and oligopsony.
Economists generally agree that real markets rarely meet the assumptions of perfect competition, but disagree on how much this affects market outcomes.