Answer:
Gold was used as the common denominator for all currencies.
Explanation:
The classical gold standard started in the 1870s and lasted until World War I. At that time, money was basically either metal coins (gold, silver or copper) or bank notes backed up by metal inventories.
Later, during the early 1940s, the US government decided to foster a new gold standard through the Bretton Woods system that was in place between 1944 up to 1973.
