Which of the following best describes SAML?

SAML, or Security Assertion Markup Language, is specifically designed for exchanging authentication and authorization data between different security domains, primarily in web-based environments. This standard supports single sign-on (SSO) capabilities, allowing users to authenticate once and gain access to multiple applications or systems without needing to log in again for each one. This is particularly beneficial in federated identity management, where a user's identity is managed across various organizations, enabling seamless access to services while maintaining secure authentication processes.

The focus on exchanging authentication and authorization data highlights the interoperability and trust established between different systems or security domains, which is integral to SAML’s functionality. This facilitates user access across diverse platforms and services while keeping security considerations intact.

The other options do not accurately capture the primary role of SAML. For instance, while the standard does involve authentication, it does not merely exchange usernames and passwords, nor is it focused on application management or directory synchronization, which are different aspects of security and identity management.