the request body.  |  ` Content-MD5: Q2hlY2sgSW50ZWdyaXR5IQ== ` |  Obsolete  [15]  |  [ RFC ](/wiki/RFC_\(identifier\) "RFC \(identifier\)") [ 1544 ](https://datatracker.ietf.org/doc/html/rfc1544) , [ 1864 ](https://datatracker.ietf.org/doc/html/rfc1864) , [ 4021 ](https://datatracker.ietf.org/doc/html/rfc4021)  
Content-Type  |  The [ Media type ](/wiki/Media_type "Media type") of the body of the request (used with POST and PUT requests).  |  ` Content-Type: application/x-www-form-urlencoded ` |  Permanent  |  [ RFC ](/wiki/RFC_\(identifier\) "RFC \(identifier\)") [ 9110 ](https://datatracker.ietf.org/doc/html/rfc9110)  
Cookie  |  An [ HTTP cookie ](/wiki/HTTP_cookie "HTTP cookie") previously sent by the server with ` Set-Cookie  ` (below).  |  ` Cookie: $Version=1; Skin=new; ` |  Permanent: standard  |  [ RFC ](/wiki/RFC_\(identifier\) "RFC \(identifier\)") [ 2965 ](https://datatracker.ietf.org/doc/html/rfc2965) , [ 6265 ](https://datatracker.ietf.org/doc/html/rfc6265)  
Date  |  The date and time at which the message was originated (in "HTTP-date" format as defined by [ RFC 9110: HTTP Semantics, section 5.6.7 "Date/Time Formats" ](//tools.ietf.org/html/rfc9110#section-5.6.7 "rfc:9110") ).  |  ` Date: Tue, 15 Nov 1994 08:12:31 GMT ` |  Permanent  |  [ RFC ](/wiki/RFC_\(identifier\) "RFC \(identifier\)") [ 9110 ](https://datatracker.ietf.org/doc/html/rfc9110)  
Expect  |  Indicates that particular server behaviors are required by the client.  |  ` Expect: 100-continue ` |  Permanent  |  [ RFC ](/wiki/RFC_\(identifier\) "RFC \(identifier\)") [ 9110 ](https://datatracker.ietf.org/doc/html/rfc9110)  
Forwarded  |  Disclose original information of a client connecting to a web server through an HTTP proxy.  [16]  |  ` Forwarded: for=192.0.2.60;proto=http;by=203.0.113.43 ` ` Forwarded: for=192.0.2.43, for=198.51.100.17 ` |  Permanent  |  [ RFC ](/wiki/RFC_\(identifier\) "RFC \(identifier\)") [ 7239 ](https://datatracker.ietf.org/doc/html/rfc7239)  
From  |  The email address of the user making the request.  |  ` From: user@example.com ` |  Permanent  |  [ RFC ](/wiki/RFC_\(identifier\) "RFC \(identifier\)") [ 9110 ](https://datatracker.ietf.org/doc/html/rfc9110)  
Host  |  The domain name of the server (for [ virtual hosting ](/wiki/Virtual_hosting "Virtual hosting") ), and the [ TCP port ](/wiki/List_of_TCP_and_UDP_port_numbers "List of TCP and UDP port numbers") number on which the server is listening. The [ port ](/wiki/Port_\(computer_networking\) "Port \(computer networking\)") number may be omitted if the port is the standard port for the service requested.  Mandatory since HTTP/1.1.  [17]  If the request is generated directly in HTTP/2, it should not be used.  [18]  |  ` Host: en.wikipedia.org:8080 ` ` Host: en.wikipedia.org ` |  Permanent  |  [ RFC ](/wiki/RFC_\(identifier\) "RFC \(identifier\)") [ 9110 ](https://datatracker.ietf.org/doc/html/rfc9110) , [ 9113 ](https://datatracker.ietf.org/doc/html/rfc9113)  
HTTP2-Settings  |  A request that upgrades from HTTP/1.1 to HTTP/2 MUST include exactly one ` HTTP2-Settings ` header field. The ` HTTP2-Settings ` header field is a connection-specific header field that includes parameters that govern the HTTP/2 connection, provided in anticipation of the server accepting the request to upgrade.  [19]  [20]  |  ` HTTP2-Settings: token64 ` |  Obsolete  |  [ RFC ](/wiki/RFC_\(identifier\) "RFC \(identifier\)") [ 7540 ](https://datatracker.ietf.org/doc/html/rfc7540) , [ 9113 ](https://datatracker.ietf.org/doc/html/rfc9113)  
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" ` |  Permanent  |  [ RFC ](/wiki/RFC_\(identifier\) "RFC \(identifier\)") [ 9110 ](https://datatracker.ietf.org/doc/html/rfc9110)  
If-Modified-Since  |  Allows a _304 Not Modified_ to be r