In the early years, credit card security codes were mainly used for overseas website purchases. You do not need to provide a password when shopping on overseas websites. You only need to provide your credit card number, expiration date and security code to complete the transaction. In recent years, some merchants in China have also begun to use security codes instead of passwords for payment, such as JD.com online payment. Most air tickets and hotel reservations are also transacted through security codes. In addition, some banks also require credit card security codes for online banking transactions.

When swiping your card outside, be careful not to let others see the credit card security code easily. If you are afraid that the security code will be leaked, you can use tape to cover the security code. Secondly, if you use a credit card security code for online shopping, remember to clear the credit card information that is automatically retained on the website. Target, a large American retailer, and China's Ctrip have both had user bank card information leaked. Finally, once you find that your credit card security code is at risk of being leaked, you can actively contact the card issuer to change the card to avoid losses.

The credit card security code has different names in different card organizations, such as:

The security code of UnionPay card (ChinaUnionPay) is called CVN2 (CardValidationNumber2), which has 3 digits. It should be printed flat on the signature line on the back of the credit card after the last 4 digits of the card number.

The security code of the VISA card is called CVV2 (CardVerificationValue2), which has 3 digits and is printed flat on the signature line on the back of the credit card at the last 4 digits of the card number.

The security code of MasterCard is called CVC2 (CardValidationCode2). It has 3 digits and is printed flat on the signature line on the back of the credit card at the last 4 digits of the card number.

The security code of American Express is called CID (CardIdentificationNumber), which is a 4-digit number and is printed flat on the front of the credit card above the credit card number.

The security code of JCB card (JapanCreditBureau) is called CAV2 (CardAuthenticationValue2), which has 3 digits and is printed flat on the signature column on the back of the credit card at the last 4 digits of the card number.