2. XML, SGML and HTML: a historical perspective

2.1 XML and SGML

XML is directly derived from SGML (Standard Generalized Markup Language), the generic markup language conceived in the early 1980s and adopted in 1986 as an ISO standard under the reference ISO 8879, which has since undergone various amendments. The W3C specification itself defines XML as "a subset of SGML whose purpose is to enable generic SGML to be transmitted, received and processed on the Web in the same way as HTML is today".

The basic principle of XML is therefore by no means a technological novelty conceived in the late 1990s, as the fad that accompanied its discovery and subsequent adoption by the Web technical community implicitly suggested. However, while SGML's use was essentially confined to the field of heavy documentary applications...