For buying foreign goods or services, or to invest in other countries, companies and individuals may need to first buy the currency of the country with which they are doing business. Generally, exporters prefer to be paid in their country’s currency or in U.S. dollars, which are accepted in the world.
When Canadians buy oil from Saudi Arabia they may pay in U.S. dollars and not in Canadian dollars or Saudi riyals, even though the United States is not involved in the transaction.
The foreign exchange market, or the "FX" market, is where the buying and selling of different currencies takes place. The price of one currency in terms of another is called an exchange rate.
The market itself is actually a worldwide network of traders, connected by telephone lines and computer screens—there is no central headquarters. There are three main centers of trading, which handle the majority of all FX transactions—United Kingdom, United States, and Japan.
Transactions in Singapore, Switzerland, Hong Kong, Germany, France and Australia account for most of the remaining transactions in the market. Trading goes on 24 hours a day: at 8 a.m. the exchange market is first opening in London, while the trading day is ending in Singapore and Hong Kong. At 1 p.m. in London, the New York market opens for business and later in the afternoon the traders in San Francisco can also conduct business. As the market closes in San Francisco, the Singapore and Hong Kong markets are starting their day.