# 3D-Secure

**3-D Secure** – a protocol used as an extra layer of security for online credit and debit cards for second-factor authentication of a user.

**Purpose** – authentication of a card holder and protection against unauthorized use of the card

**How it works**: the cardholder enters the card details, and then the issuer's website opens where the holder is asked to enter a password or a secret code.

In most cases, a code is sent as a SMS message. If the code is entered correctly, the payment will be proceeded. Otherwise, the payment will be declined.