XML is SGML Lite
XML is also an SGML application, but since XML is extensible (XML is also a metalanguage), every XML document must be accompanied by its DTD
XML is a compromise between the non-extensible, limited capabilities of HTML and the full power and complexity of SGML
XML offers “80% of the benefits of SGML for 20% of its complexity”
- XML designers tried to leave out all the SGML that would be rarely used on the web
- Note that XML specification is 30 pages and the SGML specification is 500 pages.
XML allows you to define your own tags and to describe nested hierarchies of information.