FOREX is a shortening of 'foreign exchange'. The market can be understood as a giant international network that unites the largest world banks. Among the main market participants central and commercial banks, large investing companies, and international corporations can be pointed out.
Private persons can be market participants as well, but they are not able to access the market directly. Banks, brokers and other contractors provide such access for private persons. The total amount of currencies is more than 150 while some of them are adopted by more than one country (for instance, EUR, USD, etc.).
Referring to the Forex market, currencies are not traded on their own. They are offered in pairs that show the interdependence between two different currencies (for instance, EUR/USD, USD/SGD, etc.). Thus, using EUR/USD, people purchase US dollars selling Euros. Under the influence of different economic, political and financial events, the rates of currency pairs are constantly changing.
The market participants obtain their profits from currency pairs' volatility.