In monopolistic competition theory, a single firm faces a downward-sloping demand curve due to product differentiation that grants it limited price-setting power rather than facing perfect elasticity. This structural characteristic arises from the assumption that goods are imperfect substitutes, causing the marginal revenue curve to lie below the average revenue (demand) curve within this specific market structure subfield of microeconomic analysis. The concept defines a boundary condition between perfectly competitive firms and monopolies by establishing how product heterogeneity alters consumer responsiveness to price changes in theoretical equilibrium models.
Prerequisite chain context: requires Price Elasticity of Demand Concepts in Microeconomics.