By organizing raw data into neat and friendly metaphors, GUIs make using a computer more intuitive and comprehensible. Still, sifting through the many possibilities in an effort to get to a desired task can often lead the user to wonder: "Where am I?" and "What should I do next?" The fact that the Amiga multitasks - that is, it allows the user to run a number of applications at the same time - only increases the need for strong context cues.
When your application is run, it indicates the new context by either opening up in a window or on its own screen. Thus, screens and windows provide the main cues that tell the user where they are at any given moment.