This website describes the conditions of a "perfectly competitive" market structure, and the obstacles that the individual firm in this market will face.

This site offers economics-based newspaper headlines and asks follow-up questions based on supply and demand in a perfectly competitive market.

Read about the economic ideal of perfect competition.

This site uses graphs to show how changes in demand would change a firm's output, price, and profits or losses in a monopolistically competitive market structure.

This site uses interactive graphs to show how changes in demand would change a firm's output, price, and profits or losses in a monopolistically competitive market structure.

This site lists the characteristics of an oligopoly, and discusses price competition, non-price competition, and price leadership.