The X Server

The X Server is the underlying framework that allows graphical applications to run. By itself, the X Server is not very usefulit's just a mechanism for controlling basic window placement and application window painting, and it contains no window-management functions such as the ability to move a window by dragging it with a mouse. Figure 5.1 shows an X Server running with no window manager.

Figure 5.1. Here you see a very bland and rather useless X session, running without a window manager.

Several applications are running in the X11 session shown in Figure 5.1: an xterm (a command shell terminal window), a clock, a calculator, and the GIMP image-processing program used to take this screenshot. Notice that the windows have no title bars or borders. They are not resizable or movable, and they cannot be minimized or maximized. Obviously, this lack of flexibility makes for a pretty useless graphical user interface. This is where the window manager comes in.