It is called foreign exchange option, also called currency option or foreign currency option (belonging to financial derivatives). Refers to the buyer's right to buy or sell a certain amount of foreign exchange assets at the agreed exchange rate within the validity or expiration date of the contract after paying the option fee. Mainly in dollars, euros, yen, pounds, Swiss francs, Canadian dollars, Australian dollars. For example, you agreed with a seller to buy a certain amount of dollars in RMB in the future, and when it expires, you will find that the RMB has appreciated a lot. If you perform the previous contract, you will lose a lot, so you can choose not to perform the contract and then buy more dollars in other markets with RMB, but you will lose the option fee paid to the seller in advance because of default. I hope you can understand my answer!