The Card Security Code (CSC), also called Card Verification Value or Code (CVV or CVC), is a security feature for credit card transactions on the Internet. It is a 3 or 4 digit value printed on the card.

Mastercard, Visa and Discover cards have a 3 digit code, called the "CVC2" (card validation code), "CVV2" (card verification value) and "Cardmember ID" respectively. It is not embossed like the card number, and is always the final group of numbers printed on the back signature panel of the card.

American Express cards have a 4 digit code printed on the front side of the card above the number, referred to as the "CID", or Card Identification Number. It is printed flat and not embossed like the card number.