Credit card security code is the security feature of credit card in online and telephone transactions; The signature column usually printed on the back of a credit card is the last 3 or 4 digits, which is used to prove that the payer has a credit card at the time of transaction, thus preventing credit card fraud.

If the signature column behind the credit card has seven digits, then the first four digits are generally the four-digit tail number of the card number; The last three digits are the verification codes of credit card transactions without cards, that is, the verification codes used to verify the identity of cardholders when they spend without cards. Sometimes, this verification code is also needed to activate credit cards and log in to online banking. Because many foreign trading websites can directly use the card number and security verification code to conduct transactions, once the cardholder reveals these three digits, it is easy to cause the amount in the card to be stolen.

The credit card security code corresponds to the credit card one by one, so it is suggested that the cardholder remember the security code after getting the credit card, and then cover or cross the security code printed on the card to prevent the security code from leaking.