How to learn html5?_html/css_WEB-ITnose

The poster has just entered the workplace and is a summer intern. I learned html css javascript in the teacher's laboratory. I have a basic knowledge of Java se. The company has three departments, and I was assigned to the Internet department. Our project manager went on a business trip, and there were only a few non-technical managers left in the company. They want me to learn html5.
What I want to ask is: I already have the basics of html (default refers to html4), how to learn html5? Is html5 just adding some tags on the basis of html4? You don’t need to spend a lot of effort to learn it, right? Is it enough to watch w3scool?
When I was learning web front-end, I independently made a personal blog. I should be considered to have passed the HTML level!

Reply to discussion (solution)

Although w3school is very simple, I feel it is almost the same.

Basically just look at w3scholl, but you also need some knowledge of css3 so that you can perform better.