What's the difference between credit card payments made with a CVN or without a CVN?

Credit card payments made with a 3 or 4-digit Card Verification Number (CVN) code that is on the front or back of the card improves transaction security and prevents fraud. When the cardholder isn't present in person, merchants often ask for the code so

Note: CVN capture during transaction authorization is currently not allowed. However, you may provide CVN during credit card token creation.

Credit card payments made online, by mail, fax, or over the phone without a CVN requested by the merchant, present a greater risk to the merchant because the card isn't verified as authentic by the reply message to the electronic authorization request. Additionally, in some territories and countries, credit card authorization is rejected without the CVN code.