Animation
Animation can make your application much more interesting. There are two kinds of animations: discrete-based animation, and continuous animation.
Discrete animation is based on the idea of rendering frames in succession. Since your monitor probably renders at 60 or 120Hz, and your computer is sending still images to it, all forms of rendering become discretized at some point.
Cinema, as recorded and projected on your screen, also works this way.
Photographer Eadwear Muybridge's pictures of The Horse in Motion, from
1878. Left, still images. Right, animation created from still images.
You can achieve a similar effect by rendering different images in succession. For instance, you can draw a flapping bird from a set of still images:
