Card security code (CSC) is an anti-fraud security feature. It helps to protect against fraud by helping to ensure that a person cannot use credit card details to make a transaction without being in possession of the actual card itself.
When you process an order using the Virtual Terminal, you enter the credit card’s CSC on the Enter your order page. For Visa and MasterCard, the three-digit CSC is printed on the back of the card immediately next to the card’s account number.
For American Express, the four-digit CSC is printed on the front of the card above the card’s account number.
Card security code has various names, depending on the card type. Visa calls it CVV2 and MasterCard calls it CVC2. To ensure that your customers see a consistent name, PayPal recommends using the term "card security code".
For CSC response codes, refer to Card Security Code Responses.