There is a great variety in the way that prices are formed. The equilibration of supply and demand drive prices to an equilibrium in every market. However, the means by which demand is aggregated over demanders and over suppliers varies a great deal. Suppliers may modulate price and / or quantity. Or there may be an auction process by which demand information is aggregated. Or there may be dealers holding inventory and adjusting bid and ask prices. Or prices may be set by government fiat. Each of these is a price formation process. Price formation is studied in the field of market microstructure, the study of markets at the level of individual transactions.