The X Window System

Unlike most of the window systems mentioned so far, X was not developed by a computer vendor to complement its own specific hardware. Instead, X was initially developed to provide a distributed, hardware independent user interface platform. This implies that an X application can run on more than one computer at a time, and/or on different types of computer hardware. Furthermore, X does not define any particular user interface style. Hence, the look and feel of the user interface of different X applications can be very different.

Although X was designed at Massachusetts Institute of Technology (MIT) to conquer some of the shortcomings of other window systems, it is now supported by a group of computer companies, known as the X Consortium, which has a commitment to support X as a standard for user interfaces for their products. There are several different implementations of X available, for example, the MIT X Consortium supplies X in a form that can be installed on Sun, Hewlett Packard, Apollo, VAX/VMS systems and many more. Also, various computer hardware vendors provide a proprietary implementation, typically either supplied with, or built in to, their operating system. For instance Sun supply a product called OpenWindows, Hewlett Packard, Apollo and Silicon Graphics operate in a similar manner. There are implementations for PCs and the Apple Macintosh. Regardless of the particular implementation, it is the structure of X which makes it possible for applications to run in a distributed environment of differing hardware, etc.