what is a validation code 
a validation code also known as a cvv cv2 or cvv2 code is a series of three or four numbers located on the front or back of a credit card it is intended to provide an additional layer of security for credit card transactions that take place online or over the phone most credit card issuers place their validation codes on the back of the card on the far right side of the signature panel on american express axp cards however the validation code is printed on the front of the card 1 