What is a html5?
HTML5 is the latest version of Hypertext Markup Language, the code that describes web pages. It’s actually three kinds of code: HTML, which provides the structure; Cascading Style Sheets (CSS), which take care of presentation; and JavaScript, which makes things happen.

When did HTML 5 come out?
On 28 October 2014, HTML5 was released as a stable W3C Recommendation, meaning the specification process is complete. In September 2012, the W3C proposed a plan to release a stable HTML5 Recommendation by the end of 2014 (released in October) and an HTML 5.1 specification Recommendation by the end of 2016.

What is the most recent version of HTML?
XHTML versions. XHTML is a separate language that began as a reformulation of HTML 4.01 using XML 1.0. It is no longer being developed as a separate standard. XHTML 1.0, published January 26, 2000, as a W3C Recommendation, later revised and republished August 1, 2002.