Beginner
Learn HTML in 12 Minutes (www.youtube.com)
HTML Beginner Tutorial (htmldog.com)
Marksheet (marksheet.io)
w3schools (www.w3schools.com)
Learn HTML (www.codecademy.com)
HTML Content (www.codecademy.com)
How to Use the HTML5 Sectioning Elements (blog.teamtreehouse.com)
Organizing HTML & CSS (www.codecademy.com)
Front End Interview Handbook (github.com)
HTML Fundamentals (www.codecademy.com)
HTML Best Practices (github.com)
Intermediate
HTML Intermediate Tutorial (htmldog.com)
Advanced
HTML Advanced Tutorial (htmldog.com)