> w3c's XHTML was machine understandable. It took great care to introduce rigid and reusable semantics. You could spider the web and directly extract facts with

> w3c's XHTML was machine understandable. It took great care to introduce rigid and reusable semantics. You could spider the web and directly extract facts without ML or heuristics. It did absolutely none of this. It was an presentation layer built on top of XML, and it did not really touch semantics at all. The W3C's proposed direction for the future of the web was for everybody to write data as XML, and then apply XSLT transforms to build XHTML as the structural presentation layer, with CSS providing styling information on top. XHTML added very few additional semantics, other than loose concepts that were worse than useless. > It was marginally harder to author (the mimetype issue was ridiculous), but extending it was low hanging fruit. It was difficult to author (there were days you could run random websites through the "XHTML Validator", and despite them trying, find plenty of errors). The mimetype issue was that Internet Explorer would not recognize a proper XHTML mimetype, while other browsers wouldn't turn on XHTML mode when the mimetype was text/html. https://webkit.org/blog/68/understanding-html-xml-and-xhtml/ https://webkit.org/blog/68/understanding-html-xml-and-xhtml/ -- this blog post was written as XHTML's last dying breath, and I think was the nail in the coffin for it.