“The U.S. monetary system is based on paper money backed by the full faith and credit of the federal government [fiat money]. The currency is neither valued in, backed by, nor officially convertible into gold or silver…

A gold standard uses gold – directly or indirectly – as money. In a pure gold standard, gold itself is used in transactions, with all prices in essence expressed in terms of the amount of gold needed for purchase…

A monetary system can also be regarded as a gold standard if representations of gold are used in exchange… Typically, people think of paper currency as part of a gold standard if the notes are ‘backed’ by gold, that is, if there is for every note outstanding a certain quantity of gold stored as ‘cover.’…

For paper to represent gold, it must be regarded as equivalent to a given quantity and purity of gold. In general, this equivalence is achieved by ‘convertibility,’ the commitment to exchange the notes for gold on demand… a paper money system in which notes are convertible on demand by the issuer into gold of a given weight and purity is regarded as a gold standard.”