The term 'Forex' or 'FX' is short for 'foreign exchange'. What is being exchanged on this market is not stocks or bonds, but currencies from around the world. In other words, the Forex market is the place where U.S. dollars, Euros, Yen and other major currencies are bought and sold. It represents the largest financial market in the world by volume. Starting with the simplest example of currency exchange that most people are familiar with is that of exchanging one currency for another when traveling overseas.