Forex trading is about currency trading on Forex market. The basic principle that operates on every market, applies here as well: in order to make money, you have to buy low then sell high. That's the whole philosophy.
Working non-stop with uncountable amounts of dollars, Forex is the greatest liquid financial market worldwide. You can now trade currency whenever you want, wherever you are, whoever you are. Until the 90's this kind of trading was only allowed for banks, big corporations or great dealers due to the strict regulations imposed by this market. Individuals or small businesses could not trade here.