This additional number generally located on the back of your card is an extra security feature that was created so that if someone gets possession of your card number, they would also need to have possession of your card before it can be used. Visa calls this number the Card Verification Value (CVV2). MasterCard calls it the Card Validation Code (CVC2). Below are illustrations of where to find your credit card verification number on commonly used cards.

Visa Card Verification Value (CVV2) The verification value is a 3-digit number on the back of your Visa card. The full card number is reprinted in the signature box and at the end of that number is the verification value.

MasterCard Card Validation Code (CVC2) The validation code is a 3-digit number on the back of your MasterCard card. The full card number is reprinted in the signature box and at the end of that number is the validation code.

Discover The verification number is a 3-digit number on the back of your Discover card. The full credit card number is reprinted in the signature box and at the end of that number is the verification number.