A resource identity is represented by which of the following?

• A. A numeric ID
• B. A hash
• C. An URL
• D. A name

Answer: (C)

In FHIR, a resource’s identity is the address that locates the specific resource instance on the network—the URL. Think of it as the unique web address for that exact resource, often formed by the server base, the resource type, and the resource’s local id, such as http://example.org/fhir/Patient/123. This URL uniquely identifies the resource across systems and can be used to reference or retrieve it.

A numeric ID alone isn’t globally unique across different servers, so it wouldn’t reliably identify the same resource everywhere. A hash isn’t used as the stable identifier for a resource’s identity, as hashes can change with content or context and don’t provide a consistent address for retrieval. A name isn’t guaranteed to be unique or stable either, so it wouldn’t reliably identify a single resource instance. Therefore, the URL best represents the resource’s identity, enabling unambiguous referencing and access.