Answer 1

>The Canvas API provides a means for drawing graphics via JavaScript and the HTML <canvas> element. Among other things, it can be used for animation, game graphics, data visualization, photo manipulation, and real-time video processing.

From MDN

you can use canvas for many things which is complicate or impossible with css.

You can search online for what you can do with canvas. Do check out canvas code in sololearn. You will get some idea.