Payload header

A payload header is an HTTP header that describes the payload information related to safe transport and reconstruction of the original resource representation, from one or more messages. This includes information like the length of the message payload, which part of the resource is carried in this payload (for a multi-part message), any encoding applied for transport, message integrity checks, etc.

Payload headers may be present in both HTTP request and response messages (i.e. in any message that is carrying payload data).

The payload headers include: Content-Length, Content-Range, Trailer, and Transfer-Encoding.