User interface
The user interface is the part of a system exposed to a user. In general, the system can be any kind of system with which a user may interact at will, such as a mechanical system or a computer system. For example, in an automobile the user interface consists of the steering wheel, the accelerator pedal, the brake pedal, the various instruments that the user requires, and similar facilities. In a computer system the user typically interacts with an operating system or with application software such as a spreadsheet or a word processor. With these the user interacts using menus, icons, keystrokes, mouse clicks,and similar capabilities.
Recently, as systems have become increasingly complex, and thus more difficult to control, much thought has been given to the design of interfaces that enable a user to operate the system naturally thus increasing its usability by allowing the user to form a more intuitive mental model of the system. The term user friendliness has been coined as a measure of how well the user interface fulfills this goal.
See also
de:Benutzerschnittstelle ja:ユーザーインターフェイス ru:Интерфейс пользователя he:ממשק משתמש