Currency relative values of the different currencies. Currencies in this sense are defined by governments, and each type has limited boundaries of acceptance. Other definitions of the term "currency" are discussed in their respective synonymous articles banknote, coin, and money. The latter definition, pertaining to the currency systems of nations, is the topic of this article. Currencies can be classified into two monetary systems: fiat money and commodity money, depending on what guarantees the value (the economy at large vs. the government's physical metal reserves). Some currencies are legal tender in certain political jurisdictions. Others are simply traded for their economic
Ideal money Ideal money Ideal Money (to be considered different than defining 'ideal money' without capitals) is a theoretical notion promulgated by John Nash (Nobel Laureate in Economics) to stabilize international currencies. It is a solution to the Triffin dilemma-the conflict of economic interests between the short-term domestic and long-term international objectives when a currency used in a country is also serving as world reserve currency. Nash gave various lectures and written discourses on the subject he called Ideal Money. The first talk was given in 1995 (one year after Nash won the Nobel Prize for economics for his work on equilibrium