Equilibrium Price
The price at which the quantity demanded by buyers equals the quantity supplied by sellers; also called the market-clearing price.
Surplus
The situation that results when the quantity of a product exceeds the quantity demanded. Generally happens because the price of the product is above the market equilibrium price.
Shortage
The situation that results when the quantity demanded for a product exceeds the quantity supplied. Generally happens because the price of the product is below the market equilibrium price.
Supply
The amount of a good or service that producers are willing and able to offer for sale at each possible price during a given period of time.
Demand
The quantity of a good or service that buyers are willing and able to buy at all possible prices during a period of time.