Comment by thisislife2

Seems like we keep reinventing the wheel - the previous version of of HTML, XHTML (eXtensible HyperText Markup Language) is a direct subset of XML. Also, related - Mozilla Firefox used to have something called XUL (XML User Interface Language - https://en.wikipedia.org/wiki/XUL - using which you could build complete desktop web applications with the Firefox / Gecko web engine (something that is now popular with the Chromium Embedded Framework). (After Mozilla abandoned the XUL codebase, it has been forked and is now maintained as the Unified XUL Platform (UXP) implementation - https://forum.palemoon.org/viewtopic.php?f=46&t=30840 ).