What is CSC?
CSC is generally a 3 digit code that is found on the back of Visa and MasterCards. This value is usually 4 digits for American Express and is generally found on the front of Amex cards.
This number is not printed on any sales receipts or other materials. So, if the CSC value that is provided with the credit card number matches the issuing bank's records, it is very likely that the person who provided the card number has the card in their possession.
CSIA does not retain this value, and the CSC is used to protect you and prevent fraudulent or unauthorized use of your card.

For more information about the CSC value, please visit Visa.com's official documentation.