Many games and visualizations have what we call scenes, and we need some way of managing them. 

What do I mean by scenes? Take for example, Balloon Popper 2. It has four scenes.

A start scene:
A how-to-play scene:  
A playing scene:  
A game-over scene:  


Most games have these scenes, in fact. Each scene is a distinct state of the program that displays different information. Additionally, there is some way for the user to get from one scene to the next: a simple mouse click or key press, or maybe it's selecting a scene from a menu.

Once you've realized that you need something like scenes for your program, you'll have to decide how to program them. Like many tasks in programming, there are many different approaches. We'll give you a few ideas in this tutorial.