Forex (FX) refers to the global electronic marketplace for trading international currencies and currency derivatives. It is the largest, most liquid market in the world by trading volume, with trillions of dollars changing hands every day. The forex market is open 24 hours a day, five days a week, except for holidays. The forex market is open on many holidays on which stock markets are closed, though the trading volume may be lower. Its name, forex, is a portmanteau of foreign and exchange, and it is often abbreviated as fx.

In forex trading, currencies are listed in pairs, such as USD/CAD, EUR/USD, or USD/JPY. These represent the U.S. dollar (USD) versus the Canadian dollar (CAD), the euro (EUR) versus the USD, and the USD versus the Japanese yen (JPY). Forex exists so that large amounts of one currency can be exchanged for the equivalent value in another currency at the current market rate. Some of these trades occur because financial institutions, companies, or individuals have a business need to exchange one currency for another.

The forex market is a decentralized and over-the-counter market where all currency exchange trades occur. It is an electronic network of banks, brokerages, institutional investors, and individual traders. Most of the trading is done through banks, brokers, and financial institutions. The forex market major trading centers are located in major financial hubs around the world, including New York, London, Frankfurt, Tokyo, Hong Kong, and Sydney. Despite the decentralized nature of forex markets, the exchange rates offered in the market are the same among its participants, as arbitrage opportunities can arise otherwise.

In summary, Forex (FX) is the global electronic marketplace for trading international currencies and currency derivatives. It is the largest, most liquid market in the world by trading volume, with trillions of dollars changing hands every day. Forex trading involves the exchange of one currency for another at the current market rate. The forex market is a decentralized and over-the-counter market where all currency exchange trades occur.