Markets A market is a group of buyers and sellers of a particular good or service. The terms supply and demand refer to the behavior of people .. as they interact with one another in markets Harcourt, Inc. items and derived items copyright o 200l by harcourt, IncHarcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc. Markets A market is a group of buyers and sellers of a particular good or service. The terms supply and demand refer to the behavior of people . . . as they interact with one another in markets