You may have noticed that the value of currencies goes up and down every day. What most people don't realize is that there is a foreign exchange market - or 'Forex' for short - where you can potentially profit from the movement of these currencies. The best known example is George Soros who made a billion dollars in a day by trading currencies. Be aware, however, that currency trading involves significant risk and individuals can lose a substantial part of their investment. As technologies have improved, the Forex market has become more accessible resulting in an unprecedented growth in online trading. One of the great things about trading currencies now is that you no longer have to be a big money manager to trade this market; traders and investors like you and I can trade this market.
National central banks play an important role in the foreign exchange markets. They try to control the money supply, inflation, and/or interest rates and often have official or unofficial target rates for their currencies. They can use their often substantial foreign exchange reserves to stabilize the market. Nevertheless, the effectiveness of central bank "stabilizing speculation" is doubtful because central banks do not go bankrupt if they make large losses as other traders would. There is also no convincing evidence that they actually make a profit from trading.
One unique aspect of this international market is that there is no central marketplace for foreign exchange. Rather, currency trading is conducted electronically over-the-counter (OTC), which means that all transactions occur via computer networks between traders around the world, rather than on one centralized exchange. The market is open 24 hours a day, five and a half days a week, and currencies are traded worldwide in the major financial centers of London, New York, Tokyo, Zurich, Frankfurt, Hong Kong, Singapore, Paris and Sydney - across almost every time zone. This means that when the trading day in the U.S. ends, the forex market begins anew in Tokyo and Hong Kong. As such, the forex market can be extremely active any time of the day, with price quotes changing constantly.