For almost all products, the demand curve has a negative slope: as the price increases, demand for the good decreases. Giffen goods are an exception to this general rule. Unlike other goods or services, the price point at which supply and demand meet results in higher prices and greater demand whenever market forces recognize a change in supply and demand for Giffen goods. As a result, when price goes up, the quantity demanded also goes up. To be a true Giffen good, the good's price must be the only thing that changes to produce a change in quantity demanded.