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 Basicapplication programs are eveNT-driven. See also callback. (2000-02-09)