IMPERFECT COMPETITION: Any markets or industries that do not match the criteria for perfect competition. The key characteristics of perfect competition are: (1) a large number of small firms, (2) identical products sold by all firms, (3) freedom of entry into and exit out of the industry, and (4) perfect knowledge of prices and technology. These four characteristics are essentially impossible to match in the real world. See also | market | market structure | perfect competition | monopoly | monopolistic competition | oligopoly | fifth rule of imperfection | fourth rule of competition | market control | demand curve | profit maximization | short-run production | marginal cost |
