The SMART Authorization Server authenticates clients as applicable, authorizes requests, and issues tokens. It remains a distinct participant from the protected FHIR Resource Server. For interactive flows it may rely on the IG-defined Authentication Service for user authentication without transferring its SMART conformance obligations. Backend Services does not require runtime end-user authentication. See SMART App Launch and Authorization. This IG recommends CT Time Client grouping for this server role in both interactive and Backend Services modes; see SMART Server Time Synchronization and the shared Time Synchronization deployment guidance.