Entity header

Warning: The current HTTP/1.1 specification no longer refers to entities, entity headers or entity-body. Some of the fields are now referred to as Representation header fields.

An entity header is an HTTP header that describes the content of an HTTP message (i.e. metadata about the message body). Entity headers include: Content-Length, Content-Language, Content-Encoding, Content-Type, Expires, 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:

http

POST /my-form.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