Card Security Code (CSC)
The card security code, also known as card verification value (CVV or CVV2) is a counter-measure to protect you from credit card fraud.
The security code is located on the back of MasterCard, Visa and Discover credit or debit cards and is typically a separate group of 3 digits within or to the right of the signature strip.
On American Express cards, the card security code is a printed, not embossed, group of four digits on the front towards the right.