Drawing rectangles

<html>
<body>
<canvas id="canvas"></canvas>
<script type="text/javascript">
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
ctx.fillRect(25,25,100,100);
ctx.clearRect(45,45,60,60);
ctx.strokeRect(50,50,50,50);
</script>
</body>
</html>