The main trading centers are London and New York City, though Tokyo, Hong Kong, and Singapore are all important centers as well. Banks throughout the world participate. Currency trading happens continuously throughout the day; as the Asian trading session ends, the European session begins, followed by the North American session and then back to the Asian session.
Moving back to predicting movements in the market, we must acknowledge that a trader must have a thorough comprehension of the factors that can affect the movement of a currency's exchange rate, if they want to be successful. Remember - there is no ultimate Forex prediction formula - it all depends on your own skills, experiences, the accuracy of your foreign exchange forecasting, and the commitment to succeeding. The five factors you need to understand are:
The need to exchange currencies is the primary reason why the forex market is the largest, most liquid financial market in the world. It dwarfs other markets in size, even the stock market, with an average traded value of around U.S. $2,000 billion per day. (The total volume changes all the time, but as of August 2012, the Bank for International Settlements (BIS) reported that the forex market traded in excess of U.S. $4.9 trillion per day.)