Black market exchange rate is the exchange rate at which foreign exchange is bought and sold on the black market. A black market foreign exchange supplier refers to a person who sells his foreign exchange on the black market at a price higher than the official exchange rate in exchange for more domestic currency.

Corresponding to the black market exchange rate is the official exchange rate, which refers to the exchange rate announced by the country's monetary and financial institutions (such as the central bank, the foreign exchange administration and the Ministry of Finance). The official exchange rate is legal in nature, also known as the legal exchange rate, which stipulates that all foreign exchange transactions must be based on the officially announced exchange rate. The exchange rate announced by the state monetary and financial management institution is the quotation between the domestic currency and other currencies authorized by the state to implement strict foreign exchange management.