Money supply is a way to measure currency in circulation. Its growth rate relative to inflation and GDP can indicate monetary inflation or deflation. According to the Austrian school of economics inflation is a result of a strongly rising monetary base as this process creates more money than the expansion of the economy would require.
Money supply is divided into different categories according to the size and maturity of deposits. There is no single international convention defining monetary aggregates from M0 to M4 which vary between countries. Empirical evidence has shown a strong correlation between the growth of money in circulation and rising prices.
The ECB publishes a monthly report on the growth of money supply in the Eurozone.