For Visa and MasterCard, the CVV, or Card Verification Number is a 3 digit number found on the back of your card in the signature area. Your card number should be printed here along with a three-digit number at the end. (Some newer credit cards only show the last four digits of the credit card number on the back, followed by the CVV number.)
CVV, or Card Verification Number, is an authentication mechanism created by card companies to help reduce fraud with online transactions. It requires the card holder to have the card physically in hand in order to enter three or four digits found printed on the card itself. The CVV is a number that is printed, not imprinted, on your Visa or MasterCard. This number is never transferred during card swipes and should only be known by you, the cardholder.