Foreign Exchange (FOREX) is the arena where a nation's currency is exchanged for that of another. The foreign exchange market is the largest financial market in the world, with the equivalent of over $1.9 trillion changing hands daily; more than three times the aggregate amount of the US Equity and Treasury markets combined. Unlike other financial markets, the Forex market has no physical location and no central exchange (off-exchange). It operates through a global network of banks, corporations and individuals trading one currency for another. The lack of a physical exchange enables the Forex market to operate on a 24-hour basis, spanning from one zone to another in all the major financial centers.

Traditionally, retail investors' only means of gaining access to the foreign exchange market was through banks that transacted large amounts of currencies for commercial and investment purposes. Trading volume has increased rapidly over time, especially after exchange rates were allowed to float freely in 1971. Today, importers and exporters, international portfolio managers, multinational corporations, speculators, day traders, long-term holders and hedge funds all use the FOREX market to pay for goods and services, transact in financial assets or to reduce the risk of currency movements by hedging their exposure in other markets.