Market Equilibrium: Market equilibrium occurs when the quantity demanded of a good matches the quantity supplied at a particular price level. When goods are underprovided, the market equilibrium is not reached.
Supply and Demand: Supply refers to the quantity of goods or services that producers are willing and able to sell at various price levels. Demand represents the quantity of goods or services consumers are willing and able to purchase at different prices.
Marginal Social Benefit: Marginal social benefit refers to the additional benefits society gains from consuming one more unit of a good. When public goods are underprovided, marginal social benefit exceeds marginal cost.