It is a special security feature of your Visa, MasterCard, or American Express credit card.
Because the Card Security Codes are not part of your account number and are not raised digits on your card, they are not scanned into standard credit card readers. In theory, these numbers are only visible to you, the cardholder. When you give your Card Security Code to a merchant, you assist the merchant in verifying that you are placing the order. It helps to prevent fraudulent use of your credit card account.
We ask you to enter your Card Security Code whenever you place an order online to help us detect fraudulent use of your credit card before your account is charged. This simple step enables us to greatly enhance the safety and security of our ordering process.
Flip your card over and look at the signature box. You should see a 16-digit credit card number followed by a special 3-digit code. This extra 3-digit code is your Card Security Code.
Look for the 4-digit code printed on the front of your card just above and to the right of your main, raised credit card number. This 4-digit code is your Card Security Code.