Content-Types that are acceptable for the response

Character sets that are acceptable

Acceptable version in time

List of acceptable encodings. See HTTP compression.

List of acceptable human languages for response

The Allow header, which specifies the set of HTTP methods supported.

Authentication credentials for HTTP authentication

Authentication header using Basic Auth encoding

Used to specify directives that MUST be obeyed by all caching mechanisms along the request/response chain

What type of connection the user-agent would prefer

Describes the placement of the content. Valid dispositions are: inline, attachment, form-data

The type of encoding used on the data

The language the content is in

An alternate location for the returned data

A Base64-encoded binary MD5 sum of the content of the request body

Where in a full body message this partial message belongs

The MIME type of the body of the request (used with POST and PUT requests)

The MIME type of the body of the request (used with POST and PUT requests) with an explicit encoding

The date and time that the message was sent

Indicates that particular server behaviors are required by the client

Gives the date/time after which the response is considered stale

The email address of the user making the request

The domain name of the server (for virtual hosting), and the TCP port number on which the server is listening. The port number may be omitted if the port is the standard port for the service requested.

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

Allows a 304 Not Modified to be returned if content is unchanged

Allows a 304 Not Modified to be returned if content is unchanged

If the entity is unchanged, send me the part(s) that I am missing; otherwise, send me the entire new entity

Only send the response if the entity has not been modified since a specific time

Specifies a parameter used into order to maintain a persistent connection

Specifies the date and time at which the accompanying body data was last modified

Limit the number of times the message can be forwarded through proxies or gateways

Initiates a request for cross-origin resource sharing (asks server for an 'Access-Control-Allow-Origin' response header)

Implementation-specific headers that may have various effects anywhere along the request-response chain.

Optional instructions to the server to control request processing. See RFC https://tools.ietf.org/html/rfc7240 for more details

Authorization credentials for connecting to a proxy.

Request only part of an entity. Bytes are numbered from 0

This is the address of the previous web page from which a link to the currently requested page was followed. (The word "referrer" is misspelled in the RFC as well as in most implementations.)

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 expects to receive additional headers (the trailers) after the last, zero-sized, chunk.

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

The TransferEncoding header indicates the form of encoding used to safely transfer the entity to the user. The valid directives are one of: chunked, compress, deflate, gzip, or identity.

Microsoft extension to the HTTP specification used in conjunction with WebDAV functionality.

Specifies additional communications protocols that the client supports.

The user agent string of the user agent

Informs the server of proxies through which the request was sent

A general warning about possible problems with the entity body