Forex (FX) is a portmanteau of the words foreign [currency] and exchange. Foreign exchange is the process of changing one currency into another for various reasons, usually for commerce, trading, or tourism. According to a 2022 triennial report from the Bank for International Settlements (a global bank for national central banks), the daily trading volume for forex reached $7.5 trillion in 2022.

The market is open 24 hours a day, five and a half days a week. Currencies are traded worldwide in the major financial centers of Frankfurt, Hong Kong, London, New York, Paris, Singapore, Sydney, Tokyo, and Zurich—across almost every time zone. This means the forex market begins in Tokyo and Hong Kong when the U.S. trading day ends. As such, the forex market can be highly active at any time, with price quotes changing constantly.