Which of the following describes a key aspect of SAML?

The key aspect of SAML (Security Assertion Markup Language) that makes it distinctive is its ability to facilitate identity federation across multiple systems. This means that SAML enables secure sharing of user identities and attributes among different parties, such as an identity provider (IdP) and a service provider (SP). By employing SAML, organizations can implement Single Sign-On (SSO) solutions, allowing users to authenticate once and gain access to multiple services and applications without needing to log in again for each service. This approach enhances user convenience, reduces password fatigue, and provides a more streamlined authentication process across different systems and domains.

In contrast to SAML's focus on identity federation, the other options present different concepts. While REST APIs are commonly used for other types of communications and integrations, they are not a core feature of SAML. SAML does not require both parties to authenticate users; instead, it works more on the premise of the identity provider authenticating the user and communicating that assertion to the service provider. Furthermore, SAML is not linked to database management, which is a separate domain concerning data storage and retrieval rather than user identity and authentication.