This document discusses market structures and price determination. It begins by defining key concepts like markets, prices, and price determinants. It then examines different market structures like perfect competition and monopolistic competition. Under perfect competition, the market is characterized by many small firms, homogeneous products, free entry and exit, and perfect information. Equilibrium price is reached at the point where demand and supply are equal. The document also discusses how price is determined in the short run and long run under perfect competition. Firms are price takers and price is determined by industry demand and supply. In the short run, firms can adjust variable inputs, while in the long run they can also adjust fixed inputs.