1. The CVV code of the bank card is a 3-digit or 4-digit number generated by the card number, expiration date and service constraint code, which is generally written in the user-defined data area of the magnetic stripe of the card and cannot be seen by the naked eye. The last three digits we usually see on the back of a credit card are actually CVV2, not CVV code.

2.CVC(CardVerificationCode) is a credit card verification code and an additional code printed on the back of the credit card. Also known as CVV. This code is generated by the coding rules and encryption algorithm of the issuing bank. In the payment process, if the merchant provides the last three codes to the bank, the bank will obtain the authorization of the cardholder to the merchant by default, thus allowing the transaction.

3. The CVV code of a bank card is a 3-digit or 4-digit number generated by the card number, expiration date and service constraint code, which is generally written in the 2-track custom data area of the card magnetic stripe. The last three digits usually seen on the back of a credit card are actually CVV2, not CVV code.

4. The full name of 4.cvv code is CardVerificationValue, which means credit card verification value, and it can also be called credit card security code.