The foreign exchange market (Forex, FX, or currency market) is a global decentralized market for the trading of currencies. The main participants in this market are the larger international banks. Financial centers around the world function as anchors of trading between a wide range of different types of buyers and sellers around the clock, with the exception of weekends.
According to the Bank for International Settlements. The preliminary global results from the 2013 Triennial Central Bank Survey of Foreign Exchange and OTC Derivatives Markets Activity show that trading in foreign exchange markets averaged $5.3 trillion per day in April 2013.
The foreign exchange market is the most liquid financial market in the world. Traders include large banks, central banks, institutional investors, currency speculators, corporations, governments, other financial institutions, and retail investors.