gross domestic product, especially in the short run. Yet many of the models that economists use to evaluate fundamental questions relating money and monetary policy to economic activity tend to gloss over the underlying characteristics of the economy that motivate the use of money. Economic models that simply assume currency is valued overlook these characteristics and possibly the important properties of money that influence the way its supply affects the economy. Understanding these properties will provide a better idea of not only the key features of money that associate it with “value ” but also how those characteristics affect the link between the quantity of money and aggregate economic activity.