In forex trading the currencies are always bought and sold in pairs because you are trading one currency on the prices which are relative to another currency. A currency pair is a quotation of two currencies which means what is the value of a currency if we convert it or exchange it with another one. For example, a currency pair in forex looks like this “USD/EUR 1.4250”, here the first currency is called the base currency and the second one is called the quote currency. Furthermore, it means that the base currency (USD $1) will be bought for this much quote currency (1.4250 Euros). These short forms (USD/EUR) are called the ISO currency code which identifies a currency in the forex market, every recognized currency is represented with these three letter alphabetic codes set by International Organization for Standardization (ISO).