While I am trying to understand what semantic web is and what technologies are used, I saw from <https://en.wikipedia.org/wiki/Semantic_Web#Semantic_Web_solutions>

> 
> The Semantic Web takes the solution further. It involves publishing in
>  languages specifically designed for data: Resource Description
>  Framework (RDF), Web Ontology Language (OWL), and **Extensible Markup
>  Language (XML)**. HTML describes documents and the links between them.
>  RDF, OWL, and XML, by contrast, can describe arbitrary things such as
>  people, meetings, or airplane parts.
> 
> 
> 

In Semantic web, 

* is HTML not used at all, and is XML used instead?

Is the principle of separation of semantics (content) from presentation in HTML not related to semantic web?
* Is JSON not used and is XML used instead? 

JSON is overwhelmingly used for representing data than XML, and if semantic web uses XML, does it mean that semantic web is not a trend?

In [related tags to semantic web](https://stackoverflow.com/questions/tagged/semantic-web), I find more HTML tag than XML tag, and can't find JSON tag.