Expires
Response headers
Marks the moment after which the response is considered stale.
| On the wire | Expires: … |
|---|---|
| Category | Response headers |
Headers the server attaches when it answers.
How to read this
- The first digit of a status code carries the meaning: 4 means the request, 5 means the server.
- 404 means "not there"; 403 means "there, but not for you". Swapping them makes debugging slower.
- Header names are case-insensitive — Content-Type and content-type are the same header.
- Caching and CORS problems usually come down to one header line, visible in the browser’s network tab.
Frequently asked questions
QWhat does HTTP Expires mean?
Marks the moment after which the response is considered stale.
QWhat does Expires look like on the wire?
It travels as Expires: …
QWhere does Expires appear?
In response headers.
QWhat group does Expires belong to?
The response headers group; the rest of that group is listed further down.