However, things other than price affect how much of a good or service people are willing to buy. These other determinants of demand are income, tastes, prices of related goods and services, consumers' expectations, and the number of buyers. The exchange rate is also a determinant of demand. When one of these determinants of demand changes, the whole demand schedule changes. These pictures are called demand curves .
Price is put on the vertical axis and quantity on the horizontal axis.
Demand curves slope down from left to right. When one of the determinants of demand changes, the demand curve shifts to the left or the right. Supply is the quantity of a good or service that sellers are willing and able to offer for sale at various prices. People often confuse supply with quantity supplied . Supply refers to a list of quantities and prices.