<i>It&#x27;s not like HTML except for being XML which looks a lot like SGML.</i><p>XML does not only look a lot like SGML, it is a proper subset of SGML:<p><i>XML is an application profile or restricted form of SGML, the Standard Generalized Markup Language [ISO 8879]. By construction, XML documents are conforming SGML documents.</i><p><a href="http:&#x2F;&#x2F;www.w3.org&#x2F;TR&#x2F;xml11&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.w3.org&#x2F;TR&#x2F;xml11&#x2F;</a>