A currency (from Middle English: curraunt, "in circulation", from Latin: currens, -entis), in the most specific sense is money in any form when in 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 for people in a nation. Foreign Exchange Services | Learn More About It | Citizens ... Foreign Currency Exchange Services Benefits that go beyond borders. Especially convenient for traveling customers, our Foreign Exchange Services allow you to arrive at your international destination with cash in hand. You can lock into an exchange rate and order or sell foreign currency notes at any bank branch.