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). 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 Card Identification Number (CID/4DBC) is a four-digit, non-embossed (flat) number that is printed on every American Express Card.
The CID/4DBC is ALWAYS located ABOVE the embossed (raised) account number on the face of the card. In some instances, the CID/4DBC is located on the left side of the card, but is always above the account number. Some cards have a four-digit number embossed below the account number, but this is not the CID/4DBC.
