files/en-us/web/http/reference/headers/preference-applied/index.md
The HTTP Preference-Applied header informs the client about which preferences from the {{httpheader("Prefer")}} request header were applied by the server.
The server indicates if a preference is applied to a response if it would otherwise be ambiguous for the client.
<table class="properties"> <tbody> <tr> <th scope="row">Header type</th> <td> {{Glossary("Response header")}} </td> </tr> <tr> <th scope="row">{{Glossary("Forbidden header name")}}</th> <td>No</td> </tr> <tr> <th scope="row"> {{Glossary("CORS-safelisted response header")}} </th> <td>No</td> </tr> </tbody> </table>Preference-Applied: <preference>
The following request indicates that the client prefers events to be represented in a certain time zone:
GET /events HTTP/1.1
Host: example.com
Prefer: timezone=America/Los_Angeles
The server supports the preference and sends back the content with a Preference-Applied header:
HTTP/1.1 200 OK
Content-Type: application/json
Preference-Applied: timezone=America/Los_Angeles
[
{"t":"2023-10-18T05:37:59.611-07:00"},
{"t":"2023-10-18T07:37:59.611-07:00"},
{"t":"2023-10-18T09:37:59.611-07:00"}
]
{{Specifications}}