The three digits on the back of the credit card are in the signature column, with a total of seven digits. The first four digits are the last four digits of your card number, and the last three digits are the credit card's card-not-present transaction verification code.

On the back of your credit card:

This set of numbers is the credit card security code, which is a security code for your credit card when making online or phone transactions. It is usually a 3 or 4-digit number printed on the credit card, and the location of the printing will vary on different types of cards. It is often used to prevent credit card fraud by verifying that the payer owned the credit card at the time of the transaction. The bank extracts the card account number, validity period, and service code, arranges them, and then calculates them through a series of complex algorithms. After this set of numbers is generated, only the issuing bank and the bank card holder know what the number is. The credit card security code is equivalent to the credit card's ID card. We can use this code to conduct consumer transactions. Shopping on overseas websites does not require a password. As long as the buyer provides an account number and security code, the transaction can be completed. In China, there are also merchants that have signed contracts with banks to complete phone transfers without a credit card password and only with a security code.

The following is an introduction to credit cards:

Credit cards, also called credit cards, are credit certificates issued by commercial banks or credit card companies to consumers with qualified credit. It takes the form of a card with the issuing bank's name, validity period, number, cardholder's name and other contents printed on the front, and a magnetic stripe and signature strip on the back. Consumers holding credit cards can shop or consume at specially designated commercial service departments, and then the bank will settle the accounts with merchants and cardholders. Cardholders can overdraft within the prescribed limit.

Credit cards stipulated in the relevant laws of our country ("Interpretation of the Standing Committee of the National People's Congress on Relevant Credit Card Regulations") refer to credit cards issued by commercial banks or other financial institutions with the functions of consumption payment, credit loans, transfer settlement , deposit and withdrawal of cash and other full or partial functions of electronic payment cards [1-2]. On December 1, 2017, the "English Translation and Writing Standards in the Public Service Field" was officially implemented, stipulating that the standard English name of credit cards is Credit Card [3].

Credit card consumption is a non-cash transaction payment method. There is no need to pay cash when consumption, and repayment will be made on the billing date. [4]

Credit cards are divided into credit cards and quasi-credit cards. Credit cards refer to credit cards in which the cardholder has a certain credit limit and can consume within the credit limit and then repay; quasi-credit card A credit card refers to a quasi-credit card in which the cardholder deposits a certain amount of reserve as required. When the reserve account balance is insufficient for payment, the card can be overdrawn within the prescribed credit limit. The so-called credit card generally refers to a credit card only.