It is not really the mess---see the next chapter, 13.2 Parsing HTML documents, to see the actual mess. In fact, the HTML specification defines two concrete synt

It is not really the mess---see the next chapter, 13.2 Parsing HTML documents, to see the actual mess. In fact, the HTML specification defines two concrete syntaxes for HTML where the first one is for `text/html` and another is for `application/xhtml+xml`. The latter has been never deprecated (thought the name XHTML was abolished). Moreover the spec states that: > Some authors find it helpful to be in the practice of always quoting all attributes and always including all optional tags, preferring the consistency derived from such custom over the minor benefits of terseness afforded by making use of the flexibility of the HTML syntax. To aid such authors, conformance checkers can provide modes of operation wherein such conventions are enforced. In the other words it recognizes the benefit from explicit tags, but also recognizes the benefit from optional tags. So they are equally conforming.