Canvas tutorial - Web APIs | MDN
Before you start
Using the <canvas> element is not very difficult, but you do need a basic understanding of HTML and JavaScript. The <canvas> element is not supported in some older browsers, but is supported in recent versions of all major browsers. The default size of the canvas is 300 pixels × 150 pixels (width × height). But custom sizes can be defined using the HTML height and width property. In order to draw graphics on the canvas we use a JavaScript context object, which creates graphics on the fly.