Security Assertion Markup Language 2.0 is a version of the SAML standard for exchanging authentication and authorization identities between security domains. SAML 2.0 is an XML-based protocol that uses security tokens containing assertions to pass information about a principal (usually an end user) between a SAML authority, named an Identity Provider, and a SAML consumer, named a Service Provider. SAML 2.0 enables web-based, cross-domain single sign-on, which helps reduce the administrative overhead of distributing multiple authentication tokens to the user.

The SAML metadata standard belongs to the family of XML-based standards known as the Security Assertion Markup Language published by OASIS in 2005.