> For the complete documentation index, see [llms.txt](https://docs.tarlanpayments.kz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tarlanpayments.kz/eng/acquiring/welcom/3d-secure.md).

# 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.