A graph relating demand for a good or service to its price. The price of the good is usually shown on the vertical axis and the quantity demanded at each level of price on the horizontal axis. Other factors affecting demand are assumed constant, including incomes, the prices of other goods, and influences such as fashion and the weather. A demand curve may represent the demand of an individual consumer, or of the market as a whole. The demand curve for a good is normally downward-sloping, that is, more is demanded at a lower price. The demand curve may shift if incomes or the prices of other goods alter, or if there are changes in other factors, for example competition from new products. See also compensated demand curve; downward-sloping demand curve; kinked demand curve; market equilibrium.