Money supply

Main article: Money supply
The money supply is the amount of money within a specific economy available for purchasing goods or services. The supply in the US is usually considered as four escalating categories M0, M1, M2 and M3. The categories grow in size with M3 representing all forms of money (including credit) and M0 being just base money (coins, bills, and central bank deposits). M0 is also money that can satisfy private banks' reserve requirements. In the US, the Federal Reserve is responsible for controlling the money supply, while in the Euro area the respective institution is the European Central Bank. Other central banks with significant impact on global finances are the Bank of Japan, People's Bank of China and the Bank of England.
When gold is used as money, the money supply can grow in either of two ways. First, the money supply can increase as the amount of gold increases by new gold mining at about 2% per year, but it can also increase more during periods of gold rushes and discoveries, such as when Columbus discovered the new world and brought gold back to Spain, or when gold was discovered in California in 1848. This kind of increase helps debtors, and causes inflation, as the value of gold goes down. Second, the money supply can increase when the value of gold goes up. This kind of increase in the value of gold helps savers and creditors and is called deflation, where items for sale are less expensive in terms of gold. Deflation was the more typical situation for over a century when gold and credit money backed by gold were used as money in the US from 1792 to 1913.