I'm a little confused to what HTML5 canvas is. I've been told it is JavaScript, but it seems to be a much bigger deal?
What makes it different than javascript?
Why is it so amazing?
Does it do other things than JavaScript?
I suggest you read this article HTML5 Canvas - the basics
edit: This link is ancient, there are several better resources a web-search away /OP
But in short. It does not replace javascript.
HTML 5 canvas gives you an easy and powerful way to draw graphics using JavaScript. For each canvas element you can use a "context" (think about a page in a drawing pad), into which you can issue JavaScript commands to draw anything you want. Browsers can implement multiple canvas contexts and the different APIs provide the drawing functionality.