Card Security Code
The Card Security Code (CSC) is usually a 3 - or 4 - digit number that is not part of the credit card number, but which is typically printed on the back of a credit card (usually in the signature field).
On some cards, all or part of the card number appears before the CSC, for example, 1234 567. In this example, 1234 are the last four digits of the credit card number, and 567 is the CSC.
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.
Medical Library Association
Last Updated: 2007 May 17