Provision of CVC or CVV codes is an additional security feature with credit card transactions.

Mastercard and Visa credit card
The Card Verification Code (CVC) is a three digit security code.
You will find this code on the back of your credit card on the signature strip: it consists of the last three numbers.

American Express card
The card verification value (CVV) is a four digit security code.
You will find this code on the front of your credit card above your credit card number.