cvv2 is the credit card security code. It is a security code for credit cards when conducting online or telephone transactions. It is a 3 or 4-digit number printed on the credit card. The printing position will be different for 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 security code of the VISA card is called CVV2 (Card Verification Value 2), which is a 3-digit number and is printed flat on the signature line on the back of the credit card after the 4 digits of the card number.

The security code of MasterCard is called CVC2 (Card Validation Code 2). It has 3 digits and is printed flat on the signature line on the back of the credit card after the 4 digits of the card number.

The security code of the Discover Card is called Cardmember ID, which is a 3-digit number and is printed flat on the signature line on the back of the credit card.

The security code of American Express is called CID (Card Identification Number), 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 China UnionPay is called CVN2 (Card Validation Number 2). It has 3 digits and is 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 JCB card (Japan Credit Bureau) is called CAV2 (Card Authentication Value 2). It has 3 digits and is printed flat on the signature line on the back of the credit card after the 4 digits of the card number.