Header

Description

Example

Accept Content-Types that are acceptable Accept: text/plain

Accept-Charset Character sets that are acceptable Accept-Charset: iso-8859-5

Accept-Encoding Acceptable encodings Accept-Encoding: compress, gzip

Accept-Language Acceptable languages for response Accept-Language: da

Accept-Ranges Allows the server to indicate its acceptance of range requests for a resource Accept-Ranges: bytes

Authorization Authentication credentials for HTTP authentication Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==

Cache-Control Used to specify directives that MUST be obeyed by all caching mechanisms along the request/response chain Cache-Control: no-cache

Connection What type of connection the user-agent would prefer Connection: close

Cookie an HTTP cookie previously sent by the server with Set-Cookie (below) Cookie: $Version=1; Skin=new;

Content-Length The length of the request body in octets (8-bit bytes) Content-Length: 348

Content-Type The mime type of the body of the request (used with POST and PUT requests) Content-Type: application/x-www-form-urlencoded

Date The date and time that the message was sent Date: 1994年11月15日 08:12:31 GMT

Expect Indicates that particular server behaviors are required by the client Expect: 100-continue

From The email address of the user making the request From: user@email.com

Host The domain name of the server (for virtual hosting), mandatory since HTTP/1.1 Host: en.wikipedia.org

If-Match Only perform the action if the client supplied entity matches the same entity on the server. This is mainly for methods like PUT to only update a resource if it has not been modified since the user last updated it. If-Match: "737060cd8c284d8af7ad3082f209582d"

If-Modified-Since Allows a 304 Not Modified to be returned if content is unchanged If-Modified-Since: 1994年10月29日 19:43:31 GMT

If-None-Match Allows a 304 Not Modified to be returned if content is unchanged, see HTTP ETag If-None-Match: "737060cd8c284d8af7ad3082f209582d"

If-Range If the entity is unchanged, send me the part(s) that I am missing; otherwise, send me the entire new entity If-Range: "737060cd8c284d8af7ad3082f209582d"

If-Unmodified-Since Only send the response if the entity has not been modified since a specific time. If-Unmodified-Since: 1994年10月29日 19:43:31 GMT

Max-Forwards Limit the number of times the message can be forwarded through proxies or gateways. Max-Forwards: 10

Pragma Implementation-specific headers that may have various effects anywhere along the request-response chain. Pragma: no-cache

Proxy-Authorization Authorization credentials for connecting to a proxy. Proxy-Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==

Range Request only part of an entity. Range: bytes=500-999

Referer This is the address of the previous web page from which a link to the currently requested page was followed. Referer: http://en.wikipedia.org/wiki/Main_Page

TE The transfer encodings the user agent is willing to accept: the same values as for the response header Transfer-Encoding can be used, plus the "trailers" value (related to the "chunked" transfer method) to notify the server it accepts to receive additional headers (the trailers) after the last, zero-sized, chunk. TE: trailers, deflate;q=0.5

Upgrade Ask the server to upgrade to another protocol. Upgrade: HTTP/2.0, SHTTP/1.3, IRC/6.9, RTA/x11

User-Agent The user agent string of the user agent User-Agent: Mozilla/5.0 (Linux; X11)

Via Informs the server of proxies through which the request was sent. Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1)

Warn A general warning about possible problems with the entity body. Warn: 199 Miscellaneous warning

Header

Description

Example

Accept-Ranges What partial content range types this server supports Accept-Ranges: bytes

Age The age the object has been in a proxy cache in seconds Age: 12

Allow Valid actions for a specified resource. To be used for a 405 Method not allowed Allow: GET, HEAD

Cache-Control Tells all caching mechanisms from server to client whether they may cache this object Cache-Control: no-cache

Content-Encoding The type of encoding used on the data Content-Encoding: gzip

Content-Language The language the content is in Content-Language: da

Content-Length The length of the response body in octets (8-bit bytes) Content-Length: 348

Content-Location An alternate location for the returned data Content-Location: /index.htm

Content-Disposition An opportunity to raise a "File Download" dialogue box for a known MIME type Content-Disposition: attachment; filename=fname.ext

Content-MD5 A Base64-encoded binary MD5 sum of the content of the response Content-MD5: Q2hlY2sgSW50ZWdyaXR5IQ==

Content-Range Where in a full body message this partial message belongs Content-Range: bytes 21010-47021/47022

Content-Type The mime type of this content Content-Type: text/html; charset=utf-8

Date The date and time that the message was sent Date: 1994年11月15日 08:12:31 GMT

ETag An identifier for a specific version of a resource, often a Message Digest, see ETag ETag: "737060cd8c284d8af7ad3082f209582d"

Expires Gives the date/time after which the response is considered stale Expires: 1994年12月01日 16:00:00 GMT

Last-Modified The last modified date for the requested object, in RFC 2822 format Last-Modified: 1994年11月15日 12:45:26 GMT

Location Used in redirection, or when a new resource has been created. Location: http://www.w3.org/pub/WWW/People.html

Pragma Implementation-specific headers that may have various effects anywhere along the request-response chain. Pragma: no-cache

Proxy-Authenticate Request authentication to access the proxy. Proxy-Authenticate: Basic

Refresh Used in redirection, or when a new resource has been created. This refresh redirects after 5 seconds.
(This is a proprietary/non-standard header extension introduced by Netscape and supported by most web browsers.) Refresh: 5; url=http://www.w3.org/pub/WWW/People.html

Retry-After If an entity is temporarily unavailable, this instructs the client to try again after a specified period of time. Retry-After: 120

Server A name for the server Server: Apache/1.3.27 (Unix) (Red-Hat/Linux)

Set-Cookie an HTTP cookie Set-Cookie: UserID=JohnDoe; Max-Age=3600; Version=1

Trailer The Trailer general field value indicates that the given set of header fields is present in the trailer of a message encoded with chunked transfer-coding. Trailer: Max-Forwards

Transfer-Encoding The form of encoding used to safely transfer the entity to the user. Currently defined methods are: chunked, compress, deflate, gzip, identity. Transfer-Encoding: chunked

Vary Tells downstream proxies how to match future request headers to decide whether the cached response can be used rather than requesting a fresh one from the origin server. Vary: *

Via Informs the client of proxies through which the response was sent. Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1)

Warning A general warning about possible problems with the entity body. Warning: 199 Miscellaneous warning

WWW-Authenticate Indicates the authentication scheme that should be used to access the requested entity. WWW-Authenticate: Basic