Explanation:

A demand curve is a graph depicting the relationship between the price of a certain commodity (the y-axis) and the quantity of that commodity that is demanded at that price (the x-axis). Demand curves may be used to model the price-quantity relationship for an individual consumer (an individual demand curve), or more commonly for all consumers in a particular market (a market demand curve). It is generally assumed that demand curves are downward-sloping, as shown in the adjacent image. This is because of the law of demand: for most goods, the quantity demanded will decrease in response to an increase in price, and will increase in response to a decrease in price.