What is the credit card security code?

Your credit card's security code (or CVV, CVC, or CID), is a 3 or 4 digit number that is printed, not imprinted, on your credit card. Visa, MasterCard and Discover card holders can find their 3 digit security code to the right of the signature area on the back of the card. For American Express card holders, the 4 digit number is on the front of the card to the right of the card number.