We use currently run our courses on HTML5.
This is the latest version of HTML and was created by the group named Web Hypertext Application Technology Working Group or WHATWG for short. HTML was originally developed by W3C in 2004 but then focused more on XHTML and XML. This version of HTML is more focused on the requirements of developers who work on web applications and who face other issues that were in the previous HTML versions. One of the most important features they added in HTML 5 was that they made HTML 5 backward compatibility.