The Card Security Code (CSC) is usually a 3 - or 4 - digit number, which is not part of the credit card number. The CSC is typically printed on the back of a credit card (usually in the signature field).

The number appears only on the card itself (not on receipts or statements), this provides some assurance that the physical card is in the possession of the buyer.

Visa & MasterCard Credit Card Users
Visa & Master Credit Card Users 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 3-digit code is your Card Security Code (CSC).
American Express Credit Card Users
American Express Credit Card Users
Look for the 4-digit code printed on the front of your card just above and to the right of your main credit card number. This 4-digit code is your Card Security Code.