The HTML5 <canvas> tag is used to draw graphics, on the fly, via scripting (usually JavaScript). However, the <canvas> element has no drawing abilities of its own (it is only a container for graphics) - you must use a script to actually draw the graphics. The getContext() method returns an object that provides methods and properties for drawing on the canvas.  arc( x, y, radius, sAngle=0, eAngle=0) enables you to draw a circle easily.

This reference will cover the properties and methods of the getContext("2d") object, which can be used to draw text, lines, boxes, circles, and more - on the canvas.

Below example shows how to draw circle:

<!DOCTYPE html>

<canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">
Your browser does not support the HTML5 canvas tag.</canvas>


var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.arc(100, 75, 50, 0, 2 * Math.PI);