Credit card security code is equivalent to credit card ID card, which can be used for consumer transactions. You don't need a password to shop on overseas websites. As long as the buyer provides the account number and security code, the transaction can be completed. In China, there are also merchants signing contracts with banks, but you don't need a credit card password, you only need a security code to complete the telephone transfer.
The credit card security code, like the CVV code, is the card verification value obtained by the same algorithm, except that when the card is generated, the CVV code is written into the magnetic stripe and the credit card security code is written on the card.
Extended data:
CCB's credit card security code shows 7 digits, of which the first 4 digits are the last 4 digits of the credit card number, and the last 3 digits are the security check code of the credit card. If you need a credit card security code, just enter the last 3 digits.
The generation method of credit card security code 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.
Baidu encyclopedia-credit card security code