HTML5 - Wikipedia
https://en.wikipedia.org/wiki/HTML5
HTML5 is a markup language used for structuring and presenting content on the World Wide Web. It is the fifth and last major HTML version that is a World Wide Web Consortium (W3C) recommendation.
HTML5: What's New in The Latest Version of HTML?
https://html.com/html5/
HTML5 is the latest specification of the HTML language, and represented a major break with All HTML5 documents should begin with a tag that indicated the document is, in fact, supposed to be...
HTML Style Guide and Coding Conventions
https://www.w3schools.com/html/html5_syntax.asp
A consistent, clean, and tidy HTML code makes it easier for others to read and understand your code. Here are some guidelines and tips for creating good HTML code. Always Declare Document Type.
HTML5 Reference
https://dev.w3.org/html5/html-author/
HTML5 defines three modes: quirks mode, limited quirks mode and no quirks mode, of which only the latter is considered conforming to use. The reason for this is due to backwards compatibility.
HTML5 Tutorial - An Ultimate Guide for Beginners
https://www.tutorialrepublic.com/html-tutorial/
HTML Tutorials for Beginners - Learn the fundamentals of the latest HTML5 markup language in simple and easy steps and start building your own website.