This Chapter introduces the basic concepts and principles that
are of concern to the Motif programmer. We define basic system
concepts, describe the three basic levels of the X programming
model and describe basic Motif components. X requires a system
that consists of workstations capable of bit-mapped graphics.
These can be colour or monochrome. A display is defined as a
workstation consisting of a keyboard, a pointing device (usually
a mouse although it could be a track ball or graphics tablet,
for instance) and one or more screens. X is network oriented and
applications need not be running on the same system as the one
supporting the display. This can sometimes be quite complicated
for a system such as X to manage and so the concept of clients
and servers was introduced. You need not worry too much about
the practicality of this, as normally X makes this transparent
to the user -- especially if we run programs on a single
workstation. However, in order to fully understand the workings
of X, some notion of