Demand and Quantity Demand

Demand

The quantities consumers are willing and able to buy at different prices over a given period.

Quantity demanded

The amount consumers are willing and able to buy at one particular price.

Law of demand

The principle stating that as price rises, quantity demanded falls, and as price falls, quantity demanded rises, ceteris paribus.

Movement along demand

A change in quantity demanded caused specifically by a change in the good's own price.

Demand shift

A change in the quantity bought at every price, caused by a non-price determinant.

Normal good

A type of product whose purchases rise when consumer income rises and fall when income drops.

Inferior good

A type of product whose purchases fall when consumer income rises and rise when income drops.

Consumer tastes and preferences

Subjective consumer attitudes toward a good, where greater popularity expands buying and declining popularity reduces it.

Substitute goods

Products that can replace each other, such that a higher price for one leads to higher sales of the other.

Complementary goods

Products used together, such that a higher price for one causes sales of the other to fall.

Number of consumers

The size of the buyer population, where more buyers increase overall market purchases and fewer buyers decrease them.