The window manager is responsible for manipulating windows on the screen. The window manager performs the following operations:
This task of controlling the window environment is not easy and has many facets.
For instance, there may be multiple applications running simultaneously and a conflict for input may arise:
does a keyboard input go in a window where the mouse currently points or must a window be explicitly chosen.
The appearance (look and feel) of a window manager varies a lot (compare OPEN LOOK and MOTIF window managers to see this).