Monetary policy describes the ways in which the central banks change the money supply in order to accomplish certain economic objectives. In the U.S. this is done by the Federal Reserve.

Monetarism is the theory that the proper control of a country's monetary supply is the primary determinant of that country's economic health ... conjured monetary policy by the Federal Reserve.

Fiat currencies allow central banks to manage money supply and implement monetary policy, though they can also be affected by inflation or devaluation during periods of economic instability.

C. Peter McColough Series on International Economics With Tom Barkin Richmond Fed President Tom Barkin discusses U.S. monetary policy and the outlook for inflation and labor markets. The C.