CVVtunnus

CVVtunnus, also known as the Card Verification Value or Card Verification Code, is a security feature on payment cards. It is a three or four-digit number printed on the back of the card, usually alongside the card number. The CVV is used to verify that the person making a purchase is in possession of the physical card. This helps prevent fraud by ensuring that the card is not being used by someone who has obtained the card number but not the physical card.

The CVV is typically required when making online purchases or over the phone. It is usually entered along with the card number and expiration date. The CVV is not the same as the PIN, which is used for in-person transactions at ATMs or point-of-sale terminals.

The CVV is generated by the card issuer and is unique to each card. It is not stored on the card itself, but is instead derived from the card number and other data. This means that if a card is lost or stolen, the CVV can be changed without having to reissue the card.

In some cases, the CVV may be replaced by a different security feature, such as the CVV2 or the dynamic CVV. These features provide additional security by using a different code for each transaction or by incorporating additional data into the code.