How can you tell if a website is html5?

Related questions

1. What is SGML HTML?
2. How do I view HTML in Chrome?
3. Why is method validation necessary?
4. What is valid HTML?
5. Why do we validate analytical methods?
6. What are validation errors?
7. Why do you need validation in Javascript?
8. What is website validation?
9. What is the doctype for an html5 document?
10. What is importance of validation?

Tags

1. #source
2. #webpage
3. #safari
4. #website
5. #webpages
6. #html5
7. #current
8. #doctype
9. #confirm
10. #around
11. #browser
12. #pixels
13. #narrow
14. #responsive
15. #chrome
16. #check