Demand
In economics, demand is the utility for a good or service of an economic agent, relative to his/her income. (Note: This distinguishes "demand" from "quantity demanded", where demand is a listing or graphing of quantity demanded at each possible price. In contrast to demand, quantity demanded is the exact quantity demanded at a certain price. Changing the actual price will change the quantity demanded, but it will not change the demand, because demand is a listing of quantities that would be bought at various prices, not just the actual price.)