Applications communicate with you by displaying things on the screen. You communicate with applications by typing at the keyboard or pointing to choices with the mouse.
Information that travels out of the computer (like the messages displayed on the screen) is called output. Information that travels into the computer (key presses and mouse moves) is called input.
The way an application communicates with you is called the user interface. When you are choosing applications for the Apple IIGS, you should give a lot of thought to the application's user interface because that's the personality of the application. At one extreme are hand-holding applications that guide you slowly by surely through the application. At the other extreme are applications that give you minimal instructions and leave you to your own devices. If you use an application daily, you probably won't want as much hand-holding as with an application you use only one or twice a month.
Interface is a word you'll see a lot in computer books and magazines. It refers to the way things communicate with each other. It describes both the way information is exchanged between the computer and a peripheral device (for example, serial interface) and the way information is exchanged between the computer and a person (user interface).
Communicating with an application