Forex, also known as foreign exchange, FX or currency trading, is a decentralized global market where all the world's currencies trade. The forex market is the largest, most liquid market in the world with an average daily trading volume exceeding $5 trillion. All the world's combined stock markets don't even come close to this. But what does that mean to you? Take a closer look at forex trading and you may find some exciting trading opportunities unavailable with other investments. If you've ever traveled overseas, you've made a forex transaction. Take a trip to France and you convert your pounds into euros. When you do this, the forex exchange rate between the two currencies—based on supply and demand—determines how many euros you get for your pounds. And the exchange rate fluctuates continuously.