The interaction between these two forces of demand and supply determines the price in the market. It is not the demand and supply of the single buyer and firm respectively that determine the price but it is the demand of all the buyers taken together and the supply of all the firms taken together that determine the price by their interaction. The price at which demand and supply are equal is known as an equilibrium price, since at this price the forces of demand and supply are balanced, or are in equilibrium. The quantity bought and sold (or the amount supplied or demanded) at this equilibrium price is known as the equilibrium amount. If the equality between quantity demanded and supplied does not hold for some price, buyers’ and sellers’ desires are divergent: either the amount demanded by buyers is more than that offered by sellers, or the amount offered for supply by sellers is greater than the amount demanded by buyers. In either case, the price will change so as to bring abou...