The model of competitive markets relies on the following four core assumptions: 1. There must be many buyers and sellers, none of which is large in relation to total sales or purchases. In other words, a few players can't dominate the market. 2. Each firm produces and sells a homogeneous product that is indistinguishable from all other firms’ products in a given industry. That is, buyers must regard all sellers' products as equivalent, or identical. 3. Buyers and sellers have all relevant information about prices, product quality, sources of supply, etc. 4. Firms have free entry into and exit from the industry. New firms can enter the market easily, and existing firms can exit the market easily. There are no barriers to entry or exit. The first three assumptions imply that all consumers and firms are price takers. The final assumption is not necessary for price-taking behavior, but guarantees that a market remains competitive in the long run.