Equilibrium: The point at which quantity demanded and quantity supplied are equal.
Disequilibrium: Describes any price or quantity not at equilibrium; when quantity supplied is not equal to quantity demanded in a market.
Excess Demand: When quantity demanded is more than quantity supplied.
Excess Supply: When quantity supplied is more than quantity demanded.
Price Ceiling: A maximum price that can be legally charged for a good or service.
Price Floor: A minimum price for a good or service.
Price Control: A price ceiling on rent.
Minimum Wage: A minimum price that an employer can pay a worker for an hour of labor.
Surplus: Situation in which quantity supplied is greater than quantity demanded; also known as excess supply.
Shortage: Situation in which quantity demanded is greater than quantity supplied; also known as excess demand.
Search Costs: The financial and opportunity costs that consumer pay when searching for a good or service.
Supply Shock: A sudden shortage of a good.
Rationing: A system of allocating scarce goods and services using criteria other than price.
Black Market: A market in which goods are sold illegally.
Spillover Cost: Costs of production that affect people who have no control over how much of a good is produced.