Monetary policy is the process by which the monetary authority of a country controls the supply of money, often targeting an inflation rate or interest rate to ensure price stability and general trust in the currency. Further goals of a monetary policy are usually to contribute to economic growth and stability, to lower unemployment, and to maintain predictable exchange rates with other currencies. Monetary economics provides insight into how to craft optimal monetary policy. Monetary policy differs from fiscal policy, which refers to taxation, government spending, and associated borrowing.