HTML Canvas

Canvas is used to draw shapes and animations.

## Why canvas exists
- charts
- games
- drawings

## Example
```html
<canvas id="box" width="200" height="100"></canvas>

<script>
  const c = document.getElementById("box");
  const ctx = c.getContext("2d");
  ctx.fillStyle = "blue";
  ctx.fillRect(10,10,150,50);
</script>
```

## UI Preview
A blue rectangle appears.

## Note
Canvas needs JavaScript to work.