SGML , the Standard Generalized Markup Language, deals with the structural (descriptive) markup of electronic documents.
It was made an international standard by ISO in October 1986.
SGML soon became very popular thanks in particular to acceptance in the editing world, by large multi-national companies, governmental organizations, and, more recently, by the emergence of HTML, HyperText Markup Language, the source language of structured documents on the World Wide Web.