Monetary units are standard units of currency used to measure and express the value of goods and services. Each country typically has its own monetary unit, such as the US Dollar, Euro, or Japanese Yen. These units help facilitate trade and economic transactions by providing a common reference for pricing. The value of a monetary unit can fluctuate based on various factors, including inflation, interest rates, and economic stability. Central banks, like the Federal Reserve in the United States, play a crucial role in managing these units by regulating the money supply and implementing monetary policy to maintain economic balance.