In order to process payments with Visa and Mastercard credit cards, we now need an additional element : the CVV2 or CVC2 security code. This 3 digit code is found on the back of your credit card.

What is CVV2 or CVC2 and why do you need them?
The CVV2/CVC2 is a three-digit security code that is printed on the back of credit cards. This code is used to establish that you are in posession of the card used for the payment. All MasterCard cards, both credit and debit, were required to contain CVC2 by January 1, 1997. Visa cards must have a CVV2 by January 1, 2001.

Where is CVV2 located on my card?
The CVV2 three-digit value is printed just above the signature panel in reverse italics on the back of your card. Usually it is preceded by your card number. Click for illustrations showing the location of this code on a Mastercard and on a Visa.

I found a number on the back of my card, but it has more than 3 digits
We only need the last 3 digits of this number (the other are just a repetition of your credit card number).