Source : Free On-Line Dictionary of Computing

event-driven
     
         A kind of program, such as a {graphical user
        interface}, with a main loop which just waits for {events} to
        occur.  Each event has an associated handler which is passed
        the details of the event, e.g. mouse button 3 pressed at
        position (355, 990).
     
        For example, {X window system} and most {Visual Basic}
        {application programs} are event-driven.
     
        See also {callback}.
     
        (2000-02-09)