demand is best described in the quantity of goods and service people will offer for sale at different position price the total satisfaction that each consumer of good provide people at a different price the quantity of goods or service our service that people are willing and able to purchase at different possible price the quantity of goods and service that consumer will substitute when the price of good change the additional satisfaction derived from a quantity of goods and service of pain when income increase the law of order say as the price of good increase by our willing and able to purchase list