SAML 2.0, or Security Assertion Mark-up Language 2.0, is an XML-based standard for exchanging authentication and authorization data between parties. It is commonly used for single sign-on (SSO) and federation, which allow users to use the same credentials to access multiple applications and services. SAML 2.0 provides a way for an identity provider (IdP) to securely pass information about an authenticated user, such as their username and group membership, to a service provider (SP) that trusts the IdP. The SP can then use this information to grant the user access to the appropriate resources, without the user having to enter their credentials again. SAML 2.0 is widely used in enterprise environments, and is supported by many popular identity management and SSO solutions.