Exchange rate, also known as foreign exchange rate, foreign exchange rate or foreign exchange market, refers to the exchange rate between two currencies, and can also be regarded as the value of one country's currency against another's currency. Exchange rate is a financial means for a country to achieve its political goals, and the change of exchange rate has a direct regulating effect on a country's import and export trade. Under certain conditions, the devaluation of the local currency, that is, lowering the exchange rate, will promote exports and restrict imports; On the other hand, the appreciation of the local currency, that is, the rise of the exchange rate, plays a role in restricting exports and promoting imports.

Exchange rates are usually expressed in two ways, namely, local currency exchange rate and foreign currency exchange rate. It is expressed by the number of foreign currencies that can be converted by the domestic currency in unit quantity, which is called the local currency exchange rate, and its formula is 100 @=x RMB = X foreign currency. It is expressed by the amount of domestic currency that a unit foreign currency can be converted into, which is called the foreign exchange rate, and its formula is 100 unit foreign currency = x yuan.