Money supply

The money supply (or money stock) is the total value of money available in an economy at a point of time. There are many ways to define "money". Normal measures usually include currency in circulation and demand deposits. Each country’s central bank may use its own definitions of what they consider to be money for its purposes.
Money supply data is recorded and published. It is done usually by the government or the central bank of the country. Public and private sector analysts look at changes in the money supply. This is because they believe that changes affect the price level of securities, inflation, the exchange rates and the business cycle.
Empirical measures in the United States Federal Reserve System.
Money is used as a medium of exchange, a unit of account, and as a ready store of value.
The different types of money are typically classified as "M"s. The "M"s usually range from M0 (narrowest) to M3 (broadest) but which "M"s are actually focused on in policy formulation depends on the country's central bank. The typical layout for each of the "M"s is as follows:
The ratio of a pair of these measures, most often M2 / M0, is called an (actual, empirical) money multiplier.