Content headers are the group of HTTP headers that describe the content of the body of an HTTP message, after any message framing in the body has been removed.
They specifically describe the properties of the message content that is conveyed in a particular message as it is transported, such as the length of the content, the transport encoding, which part of the resource is carried in the data (for Multi-part messages), and message integrity checks.
They differ from the Representation headers, which describe the encoding, media type, language, and other characteristics of the resource, and allow the underlying data to be interpreted....is carried in the data (for multi-part messages), and message...