Gold Standard

What Does Gold Standard Mean?
A monetary system in which a country's government allows its currency unit to be freely converted into fixed amounts of gold and vice versa. The exchange rate under the gold standard monetary system is determined by the economic difference for an ounce of gold between two currencies. The gold standard was mainly used from 1875 to 1914 and also during the interwar years. 

Investopedia explains Gold Standard
The use of the gold standard would mark the first use of formalized exchange rates in history. However, the system was flawed because countries needed to hold large gold reserves in order to keep up with the volatile nature of supply and demand for currency.   

After World War II, a modified version of the gold standard monetary system, the Bretton Woods monetary system, was created as its successor. This successor system was initially successful, but because it also depended heavily on gold reserves, it was abandoned in 1971 when U.S president Nixon "closed the gold window".