The CVV2/CVC2 is a three-digit security code that is printed on the
back of credit cards. The number appears in reverse italic at the top
of the signature panel at the end. This program helps validate that a
genuine card is being used during a transaction. All MasterCard cards,
both credit and debit, were required to contain CVC2 by January 1,
1997; all Visa cards must contain CVV2 by January 1, 2001. Even if a
criminal steals a valid account number, they cannot compute the CVV2
numbers since they do not know the mathematical algorithm logic.