Money supply refers to the total amount of money available in an economy at a given time. It includes currency and coins in circulation, as well as deposits held in bank accounts and other financial instruments that can be easily converted into cash. The money supply has a significant impact on the level of economic activity, inflation rates, and interest rates. Central banks often use monetary policy to regulate the money supply by adjusting interest rates or buying and selling government securities in order to influence the amount of money available in the economy.