An introduction to the concept of money, including its uses, purpose, and a brief account of its history. I discuss the notion of money as a medium of exchange, a unit of account, and a store of value, and some of the properties that make particular goods useful as money. I also discuss various measures of the money supply, and briefly outline the difference between the monetary base and money created through the fractional reserve system. I discuss inflation, including its definition, causes, and effects on the economy, before concluding with a brief look at interest rates and exchange rates.