You only know the card number, so you can't spend it, because you have to register online and fill in the transaction password of the card when you register. If you don't know the password, you can't even register. If it is for remote consumption (overseas shopping), you need the card number, effective date, password and verification code in the signature column on the back. And if you consume, you should write down your delivery address, and the merchants must make records for the bank to audit. If you don't pay by credit card, the card owner has the right to refuse to pay, so the bank will start to check the fee.