Entity header

The current HTTP/1.1 specification no longer refers to entities, entity headers or entity-body. Some of the fields are new referred to as representation header fields (RFC 7231, section 3: Representations).

An entity header is an HTTP header that describes the payload of an HTTP message (i.e. metadata about the message body). Entity headers include: Content-Length, Content-Language, Content-EncodingContent-TypeExpires, etc. Entity headers may be present in both HTTP request and response messages.

In the following example, Content-Length is an entity header, while Host and User-Agent are requests headers:

POST /myform.html HTTP/1.1
Host: developer.mozilla.org
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:50.0) Gecko/20100101 Firefox/50.0
Content-Length: 128

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