AVS (Address Verification System) and CVV (Card Verification Value) are both an enhanced method of fraud detection. As the name implies, the AVS compares the numeric part of the customer’s billing address and zip code or postal code to the information on file with the credit card issuer. Meanwhile, the CVV is a 3- or 4-digit number on the back of the customer’s credit card, which can be asked from the customer during checkout.