What is Semantic Web and OWL? Is it relevant or anything to do with HTML/Javascript?

I’ve started my Phd in the law field with topic of law and informatics. I’ve run into a tons of articles which have been about building ontology and using semantic web. However it was no or little information what I was able to gather so is there anyone who can give me a clue ?

My specific questions:

  1. is it still an emerging tool ? (given the fact that all the articles were written around 2008-2015)
  2. is it anything to do with HTML or Javascript?
  3. is there any good book/tutorial/course which is recommended to start with?

Thank you very much!