Currency foreign exchange rate is the price of domestic currency expressed in another country's currency, and its level is ultimately determined by the foreign exchange market. Foreign exchange transactions are generally concentrated in financial institutions such as commercial banks. The purpose of buying and selling foreign exchange is to pursue profits. The way is to buy cheap and sell expensive, and earn the bid-ask difference. The exchange rate at which they buy foreign exchange is the buying exchange rate, also known as the buying price. The exchange rate of selling foreign exchange is called selling exchange rate, also known as selling price.