1. In information technology, header refer … 1. 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 are sometimes called the payload or body. It is vital that header composition follows a clear and unambiguous specification or format, to allow for parsing.ification or format, to allow for parsing.
, 2. In a computer file, a header may be a field that precedes the main file content and describes the length of the content or other characteristics of the file.