The Forex market is a cash inter-bank or inter-dealer market established in 1971 when floating exchange rates began to materialize. The simplest definition of foreign exchange is the changing of one currency to another. In comparison to the daily trading volume averages of $300 billion in the U.S. Treasury Bond market and the less than $10 billion exchanged in the U.S. stock markets, the Forex market is huge; in September 1992 The Wall Street Journal estimated the trading volume at $1 trillion per day. Today, it is believed to have grown in excess of $1.5 trillion per day.

The most important foreign exchange activity is the spot business between the dollar and the four major currencies (British Pound, Eurodollar, Swiss Franc, and Japanese Yen). Participants in the market consist of five main groups: central banks, commercial banks, other financial institutions, corporate customers, and brokers.

But Forex is not a "market" in the traditional sense. There is no centralized location for trading activity as there is in currency futures. Trading occurs over the telephone and through computer terminals at hundreds of locations worldwide.