Representation header

A representation header (or ‘representation metadata’) is an HTTP header that describes how to interpret the data contained in the message.

For example, the content in a particular message might be encoded for transport, the whole resource might be formatted as a particular media type such as XML, JSON, HTML or Markdown, localized to a particular written language or geographical region, and/or compressed using a particular algorithm. The representation headers allow the underlying data to be extracted and understood. The underlying resource is semantically the same in each case, but its representation is different.