Credit card security code, often called CVV (CardVerificationValue) or CVC (CardVerificationCode), is an important part of ensuring the security of credit card transactions. This three- or four-digit code, despite its different names, actually represents the same concept. For example, the CVV of VISA card corresponds to CVV2, which is located next to the last four digits of the card number in the signature column on the back of the card; MasterCard uses CVC2, which is located in the same position.

The main purpose of these security codes is to verify the authenticity of the credit card held by the cardholder when conducting non-face-to-face transactions, such as online shopping or phone payments. Their existence is intended to distinguish real transaction scenarios, because CVV/CVC2 is not required when the card is swiped directly (online transactions), but is required for verification when off-site transactions (such as manual entry) to prevent fraud. Whether it is CVN2 (UnionPay Standard Card), CVC2 (MasterCard), CVV2 (VISA Card) or CSC2 (AE Express Card), the generation and verification principles are basically the same, but different card issuing organizations use different naming.

Understanding and properly keeping your credit card security code is a key step in protecting your account security. When you shop online or use a credit card where you cannot swipe the card directly, be sure to verify this code to ensure the legitimacy of the transaction.