FOREX — the foreign exchange market or currency market or Forex is the market where one currency is traded for another. It is one of the largest markets in the world.

Some of the participants in this market are simply seeking to exchange a foreign currency for their own, like multinational corporations which must pay wages and other expenses in different nations than they sell products in. However, a large part of the market is made up of currency traders, who speculate on movements in exchange rates, much like others would speculate on movements of stock prices. Currency traders try to take advantage of even small fluctuations in exchange rates.

Source: Forex trading system