Supply and Demand is an economic model of price determination in a market. Demand refers to how much (quantity) of a product or service is desired by buyers. Supply represents how much the market can offer.
In microeconomics, Supply and Demand is an economic model of price determination in a market. It concludes that in a competitive market, the unit price for a particular good will vary until it settles at a point where the quantity demanded by consumers (at current price) will equal the quantity supplied by producers (at current price), resulting in an economic equilibrium for price and quantity.
In macroeconomics, supply and demand concept is used in aggregate demand–aggregate supply model (AD–AS), to relate money supply and money demand to interest rates, and to relate labor supply and labor demand to wage rates.