UNDERSTANDING THE HISTORY OF MARKUP LANGUAGES
As mentioned earlier, the World Wide Web Consortium is the standards body charged with maintaining and developing markup languages, prior to HTML5, on the Internet.
The Standard Generalized Markup Language (SGML) is a document structure language that dates back to the mid-1980s. Its syntax is remarkably flexible, yet its implementation is very program specific. Every SGML file must begin with formal declarations — this defines all elements and attributes that can be used within — followed by the document itself. The elements and attributes, when found, dictate how the document text can be marked up to define formatting, layout, structure, and purpose.
Syntax is controlled by a structure of ...