Différencier les types de marchés

Perfect competition features many firms selling homogeneous products at prices determined by supply and demand, with firms acting as price takers and no entry barriers. Monopoly involves one firm dominating the market with a unique product, high entry barriers, and the firm acting as a price maker. The key distinction lies in the number of firms and their pricing power.

Monopolistic competition features multiple firms selling differentiated products that are close but not perfect substitutes, giving firms some pricing control. Unlike perfect competition, where products are homogeneous and firms are price takers, monopolistic competition has low entry and exit barriers but allows firms to earn short-term economic profits through product differentiation.

Oligopoly is characterized by a few large firms dominating the market with high entry barriers and interdependent pricing decisions. When one firm changes its price or output, competitors must respond, creating strategic interactions absent in other structures. Firms can sell homogeneous or differentiated products and maintain long-run economic profits due to entry barriers.

Entry barriers determine whether firms can sustain economic profits long-term. In perfect competition and monopolistic competition with low barriers, long-run profits approach zero as new firms enter. Monopolies and oligopolies maintain high entry barriers, allowing firms to earn persistent economic profits even in the long run by restricting market access.

Product differentiation distinguishes monopolistic competition and some oligopolies from perfect competition and homogeneous-product oligopolies. Differentiated products give firms pricing power and competitive advantages. In monopolistic competition, differentiation is extensive with low barriers; in oligopoly, differentiation varies but entry barriers remain high, affecting competitive dynamics and market outcomes.

Pricing power depends on market concentration and product uniqueness. Price takers in perfect competition have no control as prices are market-determined. Monopolists have maximum pricing power due to unique products and high barriers. Monopolistic competitors and oligopolists have intermediate power through differentiation or market dominance. This variation in pricing power fundamentally shapes firm strategy and market efficiency.

Perfect competition assumes perfect information for all participants, enabling efficient price discovery. In oligopoly, firms have imperfect information and are interdependent, meaning each firm's decisions affect competitors' strategies and outcomes. This interdependence creates complex strategic interactions and can lead to outcomes ranging from competitive to collusive, depending on firm behavior and public policy under oligopoly antitrust laws.