The main role of any central bank is to control a country’s money supply.
By decreasing borrowing costs, central banks are effectively increasing the money supply.
The money supply is a measure of the entire amount of bills, notes, coins, loans, credit and other liquid instruments in circulation within a country’s economy.
Money supply is measured by M0, M1, M2 and M3, with M0 being the narrowest measure of money (cash and liquid assets), and M3 being the broadest.
The money supply is an important factor to keep an eye on, especially if you want to trade FX.
Increased money supply demonstrates early signs of inflation – if the supply of money exceeds the supply of goods prices are likely to rise – hello inflation.
Back in the day the government used to set targets for the growth rate of the money supply and would often manipulate interest rates to force the supply to fall in line with their suggested brackets. In fact, many stipulate that the over manipulation of interest rates back in the 80s [a period when the US government believed the money supply was growing proportionately out of control] was actually responsible for the economic recession of that time.
It seems they learnt their lesson; governments don’t force the monetary growth to fall within their target brackets anymore. Governments nowadays just “play it by ear” waiting for the right moment to do the right thing in order to maintain stability, keep inflation in check, and promote sustainable growth.