What is a "Card Security Code"
The card security code (CSC) is a 3- or 4- digit number which is not part of the credit card number. The number appears only on the credit card itself (not on receipts or statements), so provides some assurance that the physical card is in the possession of the buyer. This reduces the chance of fraudulent card use.
For Visa, MasterCard, and Discover Card, the code is the last 3 digits of the number printed on the back of the credit card in the signature field. For American Express, it is the 4 digit number printed on the right side above the imprinted card number on the front of the credit card. See the images below to help find the code on your card.
Visa Card
MasterCard
Discover Card
American Express Card