    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. the four basic laws of supply and demand are: # if demand increases (demand curve shifts to the right) and supply remains unchanged, a shortage occurs, leading to a higher equilibrium price. # if demand decreases (demand curve shifts to the left) and supply remains unchanged, a surplus occurs, leading to a lower equilibrium price. # if demand remains unchanged and supply increases (supply curve shifts to the right), a surplus occurs, leading to a lower equilibrium price. # if demand remains unchanged and supply decreases (supply curve shifts to the left), a shortage occurs, leading to a higher equilibrium price. ==graphical representation of supply and demand== although it is normal to regard the quantity demanded and the quantity supplied as functions of the price of the goods, the standard graphical representation, usually attributed to alfred marshall, has price on the vertical axis and quantity on the horizontal axis, the opposite of the standard convention for the representation of a mathematical function. since determinants of supply and demand other than the price of the goods in question are not explicitly represented in the supply-demand diagram, changes in the values of these variables are represented by moving the supply and demand curves (often described as "shifts" in the curves). by contrast, responses to changes in the price of the good are represented as movements along unchanged supply and demand curves. ===supply schedule=== a supply schedule is a table that shows the relationship between the price of a good and the quantity supplied. under the assumption of perfect competition, supply is determined by marginal cost. that is, firms will produce additional output while the cost of producing an extra unit of output is less than the price they would receive.
Consumer_theory Demand Economics_curves Economics_laws Economics_terminology