As computer video screens became larger, particularly on engineering workstations, they were able to accommodate more visual information. To organize this information, the display was logically divided into multiple rectangular areas called windows. The X Window System, commonly called X, was developed at the Massachusetts Institute of Technology to establish an industry standard for displaying windows with text and graphics. The X Window System is designed to be independent of any particular computer hardware.
The X Window System consists of an X server, which manages a visual display, and client application programs. Client application programs can perform a variety of tasks, such as processing electronic mail, managing a database, or simply displaying the current time. Each application appears in its own window or in a family of associated windows. The server conveys user input information, such as a click of the mouse or a keystroke, to the appropriate client application. Client applications communicate their needs for display actions to the server. The X server and client applications can reside on the same computer or on different computers connected by a network.
Without specifying exactly how applications should appear or behave, the X Window System provides the programmer with a general system that supports any number of different user interfaces. Without added programming enhancements, windows in X are simple rectangles with plain borders. Motif implements a flexible software system layered on top of X to create individual visual components, such as ScrollBars and Menus. Programmers combine these components to create user interfaces that facilitate your interaction with application programs.
If you would like additional information specifically about the X Window System, refer to the X Window System User's Guide: Volume 3, Motif Edition, 1991, published by O'Reilly and Associates, Inc.