Secure Socket Layer (SSL) is a secure communications protocol that has effectively become the universal standard for authenticating websites and for encrypting communications between users and Web servers over the Internet. Because SSL is included with all major browsers and Web servers, simply installing a SSL digital certificate or Server ID will enable SSL capability for a merchant's web site.

SSL server authentication allows users to verify a merchant's Web server's identity. SSL-enabled client software, such as a Web browser, automatically checks that a server's certificate and public ID are valid and have been issued by a certificate authority (CA) listed in the client software's list of trusted CAs. SSL server authentication is vital for secure e-commerce transactions.

An encrypted SSL connection requires all information sent between a client and a server to be encrypted by the sending software and decrypted by the receiving software, protecting private information from interception over the Internet. In addition, all data sent over an encrypted SSL connection is protected with a mechanism for detecting tampering. This allows automatic determination of whether or not the data was altered in transit. This permits users to confidently transmit private data, including as credit card payment transaction information, to a website, knowing that their confidential informaiton is secured by the SSL connection.