The Card Verification Method, consists of a 3 or 4-digit numeric code that is printed at the back of the credit card along with (after) the credit card number, where the card holder signs in his signature on the card. This additional 3 or 4 digit numeric code is not embossed on the card nor available in the magnetic stripe. This additional 3 or 4 digit is code is featured / incorporated on all Master Cards and Visa cards issued worldwide. Visa calls this security feature as CVV2 and Master Card calls it as CVC2.
The purpose of this verification is to ensure that the person submitting the transaction is in possession of the actual card, since the code cannot be copied from charge slips / receipts or skimmed from the magnetic band.