There are three numbers on the right side of the white paper, and the four-digit tail number of the card number is printed under the magnetic stripe. Credit card security code is the security code of credit card for online or telephone transactions. Generally, it is a 3-digit or 4-digit number printed on a credit card, and the printing position of different types of cards will be different. It is usually used to prove that the payer has a credit card at the time of transaction, thus preventing credit card fraud. ?

The credit card security code is a set of 3 or 4 digits on the credit card. Its generation method is that the bank extracts the account number, validity period and service code of the card, arranges them and then calculates them through a series of complicated algorithms. After this set of numbers is generated, only the issuing bank and the holder of the bank card know what this number is.

: CVV password verification means that commercial banks add the verification code of self-defined algorithm to the bank card number coding rules and magnetic stripe data format they use, and the related bank cards are also called CVN bank cards.