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