HTTP/1.1: Header Field Definitions. This section defines the syntax and semantics of all standard HTTP/1.1 header fields.
For entity-header fields, both sender and recipient refer to either the client or the server, depending on who sends and who receives the entity. 14.1 Accept The Accept request-header field can be used to specify certain media types which are acceptable for the response. Accept headers can be used to indicate that the request is specifically limited to a small set of desired types, as in the case of a request for an in-line image. Accept = "Accept" ":" #( media-range [ accept-params ] )
Caching Tutorial for Web Authors and Webmasters. For Web Authors and Webmasters This is an informational document.
Although technical in nature, it attempts to make the concepts involved understandable and applicable in real-world situations. Because of this, some aspects of the material are simplified or omitted, for the sake of clarity. If you are interested in the minutia of the subject, please explore the References and Further Information at the end.
Speed Tips: Add Cache-Control Headers. Using Cache-Control headers you can specify which types of proxies can cache certain content, and how long files should be cached.
You can also add the must-revalidate header to force checking the ETag and or Last-Modified for the file to make sure the cache is using the current version. Keep in mind, if you use a far future Expires header you have to change the component's filename whenever the file changes.