what is difference between html & html5

Question

and why 5

Answer 1

html4 is the version of html we are currently using. html5 is the new version, which is still being worked on, and introduce new elements, like an audio tag and a video tag. Most modern browsers already support html5.

Answer 2

html 5 is the successor of html 4
I would say html 5 is just a better version
new functions were added)