Can the response body be absent?

Yes, it can. An example can be an HTTP response with a status code indicating the success of an operation that does not require data to be transmitted in the body.

For example:

• 204 No Content: The server successfully processed the request, but the response does not contain a body. Typically used for successful PUT or DELETE requests when there is no need to return the updated resource or a deletion confirmation.
• 304 Not Modified: The client has the current version of the resource, and the server indicates that there is no need to transmit the full version. The response contains only headers and has no body.
• Informational codes (1xx): These status codes indicate a preliminary response before the final status is received. They do not contain a body.

In these cases, all necessary information is transmitted through response headers.