CVV2 is a number printed in the signature area of Visa/Master Card card. It is located in the 3 digits after the credit card number. The last three digits we usually see on the back of a credit card are actually CVV2, not CVV code. CVV2 and CVC2 are also the card verification values obtained by the same algorithm, but they are printed on the signature strip when the card is generated. CVV/CVC shall be checked during online transaction (credit card swiping), and CVV2/CVC2 shall be checked during off-site transaction/manual transaction (credit card swiping is not possible). VISA CVV and MC CVC are 3-digit or 4-digit numbers generated by card number, expiration date and service constraint code, which are generally written in the 2-track user-defined data area of card magnetic stripe. CVV and CVC are generated in the same way, but they are called differently.