3D Secure is an XML-based protocol developed to add an extra layer of security for online credit and debit card transactions. Visa was the first card provider to implement the protocol, with the intention of improving online-payment security. 3D Secure is now offered to customers under the name "Verified by Visa." MasterCard SecureCode is another implementation of 3D Secure.
In broad terms, 3D Secure is a fraud and AML prevention scheme that adds an authentication step for online payments. 3D Secure offers companies liability cover for transactions, providing much-needed protection against fraud and money-laundering schemes.