CVV
Card Verification Value / CVCAuth & security
The 3- or 4-digit security code printed on the back (front for Amex) of a card. Required for most card-not-present transactions. Match on CVV is one of the strongest fraud-screening signals because the CVV is not encoded on the magnetic stripe and is not stored by PCI-compliant merchants.
In practice.
The CVV check proves the buyer has the physical card, which stops basic stolen-number fraud. Merchants cannot store it after authorization under PCI DSS, which is precisely what makes it useful. Like AVS, it works best as a signal feeding a risk decision rather than a blanket rule.
Auth & security