terms of U.S. dollars, while the U.S. dollar itself is commonly quoted in the Japanese yen, British pound and the Euros.
Here is an example to depict why foreign exchange service is required. A person traveling from the U.S. to Australia would require the Australian currency during his stay there. He would then be required to go to a money exchanger and get dollars exchanged for Australian Dollars at the exchange rate existing on that day.
All trades related to foreign exchange are based on purchasing one kind of currency against another. This gives rise to the concept of pairs like the Euro/U.S. Dollar. The first currency in the pair is referred to as the base currency (the one that provides a baseline for the purchase or sale) while the second one is termed as the counter or quote currency. While buying, an exchange rate specifies how much should be paid in the counter or quote currency to obtain one unit of the base currency whereas selling involves how much shall be received in counter or quote currency upon selling one unit of the base currency. The 15 important currency pairs are EUR/USD, USD/JPY, GBP/USD, USD/CHF, USD/CAD, AUD/USD, EUR/JPY, EUR/GBP, EUR/CHF, GBP/JPY, AUD/JPY, CHF/JPY, EUR/AUD, GBP/CHF, and NZD/USD . Foreign exchange quotes are a relation between currencies. For example, quote USD/JPY 108,91 would mean that 1 U.S. Dollar costs 108,91 Japanese Yens. market is considered the largest and most liquid market in the world, trading around $2 trillion on an average every day. It is larger than all equity markets combined.