FOREX is the largest financial market in the world in terms of both size and liquidity. To give you a general idea of the size, an average of $3 trillion is traded globally each day. No stock market in the world trades such a huge amount on a daily basis.
The idea of FOREX is simple really; it’s the exchange of one country’s currency for the currency of another country. With FX you’re essentially buying one currency, and selling the other and so naturally FX is traded in pairs such the pound and the US Dollar [GBP/USD]. There are some “FX pairs” that are more popular than others, Euro vs. US Dollar [EUR/USD], British Pound vs. US Dollar [GBP/USD], US Dollar vs. Japanese yen [USD/JPY], and US Dollar vs. Swiss Franc [USD/CHF]. These four popular currency pairs are often referred to as “the Majors”
At almost any point during the day there is always a financial centre somewhere in the world open for business. The FX market is open 24 hours a day and only closes at weekends between 22:00 (GMT) on Friday and 22:00 (GMT) on Sunday.
The Foreign Exchange market is homeless; by that we mean that it has no set physical location. Homeless markets are known as OTC [Over-the-Counter] markets in which all trades are processed electronically 24 hours a day between banks around the world. Forex, unlike other financial markets, does not have an exchange centre so you can pretty much trade FX anywhere in the world, at any point in time but there are some peak trading session times in each region.