The CVC (also referred to as CVV) is the three- or four-digit number printed directly on the credit card, usually either on the signature strip or the front of the card. Radar includes a built-in rule to block any payments that fail the CVC verification check (note that this does not affect payments where the CVC check could not be performed). This can be enabled or disabled within the Dashboard.
In general, only cardholders in physical possession of the card should have access to the CVC number. Businesses are not permitted to store the CVC number, so it’s unlikely that a fraudster can obtain this information through a computer breach. However, CVC verification does not protect against physical theft of a card, or card information used on a compromised computer or website that isn’t secure.