The foreign exchange market is the largest and most liquid financial market in the world, with an estimated daily trading volume of $7.5 trillion according to the Bank for International Settlements (BIS). This figure is more than the annual GDP of most countries and dwarfs other financial markets. In this enormous market, currency pairs are the basic building blocks of all forex trading. It is important to understand the major forex pairs and, more importantly, what makes them popular and attracts the most trading volume. Popular pairs have a few advantages for both rookie and professional traders: their huge liquidity allows you to enter and exit positions with ease; their small spreads lower your trading costs; and their greater transparency means more effective price discovery and technical analysis. When you go overseas and exchange dollars at the airport for euros, you are participating in essentially the same process driving the EUR/USD currency pair, the most p...