In information technology, header refers to supplemental data placed at the beginning of a block of data being stored or transmitted. In data transmission, the data following the header is sometimes called the payload or body.

It is vital that header composition follows a clear and unambiguous specification or format, to allow for parsing.


See also


  1. ^ P. Resnick, ed. (October 2008), Internet Message Format, Network Working Group, RFC 5322
  2. ^ B. Leiba (March 2013), "Update to Internet Message Format to Allow Group Syntax in the "From:" and "Sender:" Header Fields", Ietf Request for Comments (RFC) Pages - Test, Internet Engineering Task Force (IETF), ISSN 2070-1721, RFC 6854