There are two ways to quote a currency pair, either directly or indirectly. A direct currency quote is simply a currency pair in which the domestic currency is the base currency; while an indirect quote, is a currency pair where the domestic currency is the quoted currency. So if you were looking at the Canadian dollar as the domestic currency and U.S. dollar as the foreign currency, a direct quote would be CAD/USD, while an indirect quote would be USD/CAD. The direct quote varies the foreign currency, and the quoted, or domestic currency, remains fixed at one unit. In the indirect quote, on the other hand, the domestic currency is variable and the foreign currency is fixed at one unit.
For example, if Canada is the domestic currency, a direct quote would be 0.85 CAD/USD, which means with C$1, you can purchase US$0.85. The indirect quote for this would be the inverse (1/0.85), which is 1.18 USD/CAD and means that USD$1 will purchase C$1.18. Most currencies in the interbank market are quoted in European terms, that is, the U.S Dollar is priced in terms of the foreign currency (an indirect quote from the U.S perspective). By convention, however, it is standard practice to price certain currencies in terms of the U.S Dollar, or in what is referred to as American terms (a direct quote from the U.S perspective.
Foreign Exchange Market and Exchange Rate
The foreign exchange market (forex, FX, or currency market) is a global decentralized market for the trading of currencies. The main participants in this market are the larger international banks. Financial centers around the world function as anchors of trading between a wide range of different types of buyers and sellers around the clock, with the exception of weekends. Electronic Broking Services (EBS) and Reuters 3000 Xtra are two main interbank FX trading platforms. The foreign exchange market determines the relative values of different currencies.