Market Structure: Market structure refers to the characteristics of a market such as the number of firms operating in it, barriers to entry/exit, product differentiation (or lack thereof), etc.
Monopolistic Competition: Monopolistic competition is a market structure characterized by many firms selling similar but slightly differentiated products. Each firm has some control over its price due to product differentiation.
Price Elasticity of Demand: Price elasticity of demand measures how sensitive consumer demand is to changes in price. It helps determine how much quantity demanded will change when there is a change in price.