Demand and Supply- Or Supply and Demand  

Ceiling Price:

A maximum price at which a product may legally be sold.

Complements:

Goods that are used with each other.

Demand Schedule:

A table showing different prices for a good and the quantity of that good demanded at each of these prices. 

Disequilibrium:

A market state in which the quantity demanded does not equal the quantity supplied.

Equilibrium Price:

The price that equates quantity demanded with quantity supplied in a market.

Equilibrium Quantity:

A quantity of a good or service that equates the quantity supplied and the quantity demanded at a particular price in a market.

Excess Demand:

The extent to which the quantity demanded exceeds the quantity supplied. 

Excess Supply:

The extent to which the quantity supplied exceeds "the quantity demanded.

Floor Price (support price):

A minimum price that is legally set for a product.

Free Market:

A market in which the forces of demand and supply determine the price.

Income Effect:

The influence that a change in a person's real income (resulting from a change in the price of a good or service that this person buys) has on the quantity that this person demands of that good or service. 

Individual Consumer Demand:

The quantity of a good or service that an individual consumer is willing and able to purchase at a particular moment at each possible price that might be charged for that good or service. 

Individual Firm Supply:

The quantity of a good or service that an individual business firm is willing and able to sell at a particular moment at each possible price that might be charged for that good or service. 

Market:

The organized action between potential buyers and potential sellers that enables them to carry on exchange or trade. 

Market Demand:

The sum of all of the individual consumers demands for a particular good or service in a certain place over some period of time.

Market Supply:

The sum of all the individual firms, supplies of a particular good or service in a certain place over some period of time.

Movement Along a Demand Curve:

A change from one point on a demand curve to another point on the same curve due to a change in the price of the product.

Movement Along a Supply Curve:

A change from one point on a supply curve to another point on the same curve due to a change in the price of the product. 

Rationing:

Any method of restricting the demand for a good or service. Government may formally invoke a system of rationing in order to deal "fairly " with what would otherwise be an excess demand situation.

Real Income:

The purchasing power of a person's money income.  

Shift of the Demand Curve:

A displacement of an entire demand curve to the right or left showing a change in demand.

Shift of the Supply Curve:

A displacement of an entire supply curve to the right or left showing a change in supply.  

Shortage:

The extent to which the quantity supplied of a good or service is less than the quantity demanded for it.

Substitutes:

Goods that may be used instead of one another.

Substitution Effect:

The effect that a change in relative prices of substitute goods or services (resulting from a change in the price of a good or service) has on the quantity that a person demands of that good or service. 

Supply Schedule:

A table showing different prices for a good and the quantity of that good supplied at each of these prices 

Support Price:

See floor price. 

Surplus:

The amount of excess supply that stems from a disequilibrium situation.