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
S-train expansion and new trains). Plans for further extension of system include another two lines, one of which should reach Belgrade Nikola Tesla Airport. "S-Bahn" is also used in German-speaking Switzerland. While French publications of those networks translate it as "RER", the line numbers are still prefixed with an S (e.g. S2). The oldest network in Switzerland is the Bern S-Bahn, established in stages from 1974 and has adopted the term S-Bahn since 1995. It is also the only one in Switzerland to use a coloured "S" logo. In 1990, the Zürich S-Bahn, which covers the largest area, went into service.