An interface should be simple (not simplistic), easy to learn, and easy to use. It must also provide access to all functionality provided by an application. Maximizing functionality and maintaining simplicity work against each other in the interface. An effective design balances these objectives.
One way to support simplicity is to reduce the presentation of information to the minimum required to communicate adequately. For example, avoid wordy descriptions for command names or messages. Irrelevant or verbose phrases clutter your design, making it difficult for users to easily extract essential information. Another way to design a simple but useful interface is to use natural mappings and semantics. The arrangement and presentation of elements affects their meaning and association.
You can also help users manage complexity by using progressive disclosure. Progressive disclosure involves careful organization of information so that it is shown only at the appropriate time. By "hiding" information presented to the user, you reduce the amount of information to process. For example, clicking a menu displays its choices; the use of dialog boxes can reduce the number of menu options.
Progressive disclosure does not imply using unconventional techniques for revealing information, such as requiring a modifier key as the only way to access basic functions or forcing the user down a longer sequence of hierarchical interaction. This can make an interface more complex and cumbersome.
For information about applying the principle of simplicity, see Chapter 7, "Menus, Controls, and Toolbars." This chapter discusses progressive disclosure in detail and describes how and when to use the standard (system-supplied) elements in your interface.