What is Forex?

Forex is an acronym commonly used for foreign currency trading and is usually used to trade in foreign exchange by the investor and the speculator or market maker. For example, in the illustrated when the U.S. dollar is expected to be weakened against the euro. 

Then a foreign currency trader will sell his dollars and soon owned to buy the euro currency, the purpose of this transaction is done to protect the value as well as to gain an advantage on foreign currency trading. It is similar to stock trading. A stock trader will buy the stock if they have to analyze and predict as well as price approaches that stock prices will rise in the future, then the trader will buy shares of stock today and sell off or stock later on for profit.

Likewise his case against a forex trader will buy the currency and expect the exchange rate to rise in the future. Its all covered in forex trading strategies.