The foreign exchange market (currency, forex, or FX) is where currency trading takes place. It is where banks and other official institutions facilitate the buying and selling of foreign currencies.
FX transactions typically involve one party purchasing a quantity of one currency in exchange for paying a quantity of another. The foreign exchange market that we see today started evolving during the 1970s when worldover countries gradually switched to floating exchange rate from their erstwhile exchange rate regime, which remained fixed as per the Bretton Woods system until 1971.
Presently, the FX market is one of the largest and most liquid financial markets in the world, and includes trading between large banks, central banks, currency speculators, corporations, governments, and other financial institutions. The average daily volume in the global foreign exchange and related markets is continuously growing. Traditional daily turnover was reported to be over US$3.2 trillion in April 2007 by the Bank for International Settlements. Since then, the market has continued to grow. According to Euromoney's annual FX Poll, volumes grew a further 41% between 2007 and 2008.
The purpose of FX market is to facilitate trade and investment. The need for a foreign exchange market arises because of the presence of multifarious international currencies such as US Dollars, Euros, Japanese yen, Pounds Sterling, etc., and the need for trading in such currencies.