XML.com FAQs > C. Authors of SGML (including writers of HTML: Web page owners)
Question:  C.1 Does XML replace HTML?

No. XML itself does not replace HTML: instead, it provides an alternative which allows you to define your own set of markup elements. HTML is expected to remain in common use for some time to come, and a Document Type Definition for HTML is available in XML syntax as well as in original SGML. XML is designed to make the writing of DTDs much simpler than with full SGML. (See the question on DTDs for what one is and why you might want one.)

This FAQ is from The XML FAQ, maintained by Peter Flynn