HTTP: The Definitive Guide
| Expires |
The Expires header gives a date and time at which the response is no longer valid. This allows clients such as your browser to cache a copy and not have to ask the server if it is still valid until after this time has expired.
Chapter 7discusses how the Expires header is usedin particular, how it relates to caches and having to revalidate responses with the origin server.
Type
Entity header
Basic Syntax
Expires: HTTP-date
Example
Expires: Thu, 03 Oct 1997 17:15:00 GMT