HTML

Web Fundamentals from Codecademy

Codecadamy tutorials teach you the building blocks of Web development with HTML and CSS, and enable you to create your own website by the end of the course. Currently free but requires you to create an account. Practice projects and quizzes require a Pro (paid) membership.

https://www.codecademy.com/catalog/language/html-css

HTML Goodies

A tutorial site for beginning through advanced HTML users; includes help on Java and XML.

https://www.htmlgoodies.com

W3schools HTML Tutorial

HTML tutorial includes basic and advanced, examples, references, and an online quiz.

https://www.w3schools.com/html/default.asp

HTML Code Tutorial

Includes tutorials on a number of topics, including applets, CSS, document tags, embedded objects, fonts, forms, frames, images, scripts, sounds, and more.

https://www.html.com