Card Verification Value (CVV) number

The three-digit number on the back of Visa Inc. and MasterCard Worldwide credit and debit cards. It is used as a security feature in card-not-present transactions. The CVV number helps guard against the use of data stolen from payment networks by hackers. Intercepted data will usually comprise the cardholder name, card number and card expiration date, but not the CVV, which is generally obtained only by viewing the physical card.