In forex, a currency is a medium of exchange that is used to buy or sell goods and services, pay for debts, or other financial obligations. Currencies are issued by national governments, and their values are determined by supply and demand forces in the foreign exchange market. Some of the major currencies include the U.S. dollar, euro, Japanese yen, British pound, Swiss franc, Canadian dollar, Australian dollar, and New Zealand dollar. The foreign exchange market is the largest financial market in the world, with an estimated daily turnover of over $5 trillion.