demand
the relationship between possible prices of a good or service and the quantities that individuals are willing and able to buy over a time period, ceteris paribus
law of demand
a law stating that as the price of a good falls, the quantity demanded will increase over a certain period of time, ceteris paribus
market
any arrangement where buyers and sellers interact to carry out an economic transaction
market demand
the sum of the individual demand curves for a product of all consumers in a market