The somewhat unpleasant fish emerged as the currency of choice in many federal prisons in 1994 when cigarettes, the previous commodity used as currency, were banned. Plastic bags of mackerel sold for about $1 in prison commissaries. Almost no one likes them, so the prison money supply did not get eaten. Prisoners knew other prisoners would readily accept macks, so they were accepted in exchange for goods and services. Their $1 price made them convenient as a unit of account. And, as Mr. Levine’s experience suggests, they acted as a store of value. As we shall see, macks served all three functions of money—they were a medium of exchange, a unit of account, and a store of value.^[27]

In this chapter and the next we examine money and the way it affects the level of real GDP and the price level. In this chapter, we will focus on the nature of money and the process through which it is created.

As the experience of the prisoners in Lompoc suggests, virtually anything can serve as money. Historically, salt, horses, tobacco, cigarettes, gold, and silver have all served as money. We shall examine the characteristics that define a good as money.

We will also introduce the largest financial institution in the world, the Federal Reserve System of the United States. The Fed, as it is commonly called, plays a key role in determining the quantity of money in the United States. We will see how the Fed operates and how it attempts to control the supply of money.