Currency Currency A currency (from , "in circulation", from ), in the most specific use of the word, refers to money in any form when in actual use or circulation as a medium of exchange, especially circulating banknotes and coins. A more general definition is that a currency is a "system of money" (monetary units) in common use, especially in a nation. Under this definition, US dollars, British pounds, Australian dollars, European euros and Russian ruble are examples of currency. These various currencies are recognized as stores of value and are traded between nations in foreign exchange markets, which determine the
World currency a single world currency is unnecessary, because the U.S. dollar is providing many of the benefits of a world currency while avoiding some of the costs. If the world does not form an optimum currency area, then it would be economically inefficient for the world to share one currency. In the present world, nations are not able to work together closely enough to be able to produce and support a common currency. There has to be a high level of trust between different countries before a true world currency could be created. A world currency might even undermine national sovereignty