World currency has good market size and Forex is a virtual world where the currencies are traded in real-time and it is also the place where currency is converted from one to another. Forex is important because internationally some goods are purchased in US dolor. Oil producing nations force the buyers to convert currency for making payments. UN aids and other international assistance is converted into dolor first then to local currency and is transferred to the receiving country. Forex rates affect the import and export for one nation. If you wish to understand this live market, you will need to keep tab on international situations. Oil seems to be the single largest factor affecting the price but political and the demand for import goods also make a point. Many banks and retail operators are always active in the market. These operators rely on the margins and deposited funds. The value of the deposit goes up and down according to the prevailing rates in international market.