Card Code Verification Number
The credit card verification (CCV) number is a 3- or 4-digit number that is printed on the back of Visa, MasterCard, and Discover credit cards and on the front of American Express cards.
Visa
3-digit, non-embossed number printed on the signature panel on the back of the card immediately following the Visa card account number. This number is recorded as an additional security precaution.
MasterCard
3-digit, non-embossed number printed on the signature panel on the back of the card. This number is recorded as an additional security precaution.
AMEX
4 digit, non-embossed number printed above your account number on the face of your card. This number is recorded as an additional security precaution.