Supply and demand is a model of microeconomics. It describes how a price is formed in a market economy. There are two determining factors on such a market, the number of things made available, called supply, and the number of things consumers want, called demand. Supply and demand shows how producers and consumers interact with each other. This relationship will fix the price for a certain type of good. In perfect competition, the quantity demanded (demand) and the quantity supplied will be equal. This happens at the equilibrium market price.