CVV is what people often call the credit card security code. The security code is printed on the face of the credit card. It is usually the last three digits of the signature field on the back of the credit card. Some CVV codes are 4 digits. Different types of credit card security codes are printed in different positions. This CVV is equivalent to the credit card's ID card.

Credit card holders can make consumption transactions with the credit card security code. Generally, when people make transactions through the Internet or over the phone, they can make payment transactions with the credit card number, expiration date and security code.

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1.CVV, namely Card Verification Value. VISA CVV is a 3-digit or 4-digit number generated from the card number, validity period and service restriction code. It is generally written in the 2-track user-defined data area of ??the card's magnetic stripe. CVV2 is a number printed in the signature area of ??a Visa/MasterCard card and is the 3 digits after the credit card number. CVV information is stored in the magnetic track of the magnetic stripe bank card. Based on the card number, track master account number, card-issuing bank logo code and other information, it is encrypted through a special encryption algorithm customized by each bank. Each step is encrypted using CVKA technology to obtain the verification code. . Since the encryption algorithms of different banks are different, some counterfeit cards illegally produced using the obtained bank card information can be identified and cannot be used when the card issuer decrypts them.

2. Precautions for use: Do not write credit card information on the computer; do not give credit cards to others easily; after losing your credit card, call the bank customer service number immediately to report the loss; credit card is a payment and settlement tool based on the credit system. Therefore, please take your monthly statement seriously and confirm your purchases. If some abnormal consumption is found, payment can be refused by providing evidence. If you think it is dangerous to tell the credit card number, expiration date and other information, it is recommended that you pay through online payment, because the credit card information will be entered into the bank's online banking, and all information will not be saved in the hands of the merchant.

3. In order to prevent more and more crimes of stealing credit card information, banks in major cities have given cardholders specific tips. For example, in a letter sent to credit card owners, a bank employee emphasized that information such as credit card number and expiration date are important documents for transactions. Please keep your card number, expiration date and other personal information properly, and do not tell others about your credit card. The bank also reminds: When applying for a credit card, you can indicate the purpose of use in a prominent position, such as "Only at XX Bank, apply for credit card, copying is invalid" to prevent the data from being used for other purposes.