A credit card number is a series of numbers printed on the front of the credit card, usually 16 digits.

The current 16-digit card number is an international standard. The first 6 digits are BIN, which are assigned by international card organizations. The first 4 is a VISA card, the 5 is Master, and 622126~622925 is a UnionPay standard card. Cards starting with 6 are China UnionPay single currency cards (or American discover), cards starting with 4 are international brand VISA credit cards (the world's number one credit card organization), cards starting with 5 are international brands MASTERCARD, and cards starting with 3 are Japanese JCB and American AMERICAN EXPRESS.

The 7th to 15th digits are assigned to each row according to their own needs according to their regional affiliation, and the 16th digit is the check digit.

Other non-16-digit card numbers are formulated and assigned by each bank.