Motif is a software environment for implementing graphical user interfaces. Applications created with Motif include all the elements that characterize a modern user interface, such as overlapping windows, dialog boxes, and menus. Motif is available for UNIX and VMS and has a good chance of becoming the standard for these operating systems. Motif consists of a toolkit, a description language, a window manager, and a style guide. This book describes the programming of applications using the Motif toolkit. The Motif toolkit provides building blocks for graphical user interfaces, known as widgets. It is based on the X Window System and the X Toolkit Intrinsics from MIT. However, the toolkit does not cover all aspects of an application. Therefore, the necessary knowledge about X and the intrinsics is also provided.