Common header fields
| Field | Direction | Purpose |
|---|---|---|
Accept | request | Media types acceptable for the response. |
Accept-Encoding | request | Content codings acceptable for the response. |
Authorization | request | Credentials for the target resource. |
Cache-Control | both | Directives for caches along the request chain. |
Content-Length | both | Size of the message body in octets. |
Content-Type | both | Media type of the enclosed representation. |
ETag | response | Opaque validator for the current representation. |
Host | request | Target host and port of the request URI. |
Last-Modified | response | Timestamp the representation last changed. |
Location | response | URI for redirection or for a created resource. |
Range | request | Request only part of a representation. |
Retry-After | response | How long the client should wait before retrying. |
Vary | response | Request fields used to select the representation. |
Field syntax
Field names are case insensitive. A recipient may combine multiple field lines with the same name into one comma separated value, except for Set-Cookie.