A window manager is a special system software which controls the placement and appearance of windows. This control occurs within a windowing system in a graphical user interface. The vast majority of window managers is designed to help establish a desktop environment. These window managers work in connection with the underlying graphical system that provides required functionality like support for graphics hardware, pointing devices, and a keyboard. Besides this sort of window managers is often written and created using a so-called widget toolkit.
Few window managers are characterized using a clear difference between the windowing system and the window manager. Every graphical operating system that uses a so-called windows metaphor is operating to some extent like a window management. In practice however the elements of this functionality vary greatly. The elements usually associated with window managers are those which give the user the possibility to open, close, minimize, maximize, move, resize, and keep track of running windows, including window decorators. Many window managers also come with docks, task bars, program launchers, desktop icons, and wallpaper.
Beryl is an example for an open source window manager that tried to provide a free desktop experience to the community that went along with the wishes of the users. This is simply a form of placing software at the disposal. Other than that mentioned there exist further more forms of placing something at the general public’s disposal. Examples therefore are poets who publish their poems, citations and sayings, in German Gedichte, Zitate and Sprüche, in communities and share them with others. Consequently there emerge big collections of lyrical and poetical works from which people choose poems for birthday cards or any other festive reason. In addition also film and movie quotes, in German Filmzitate, get collected in wide open source communities and online platforms.
On systems using the X window system, there is a clear distinction between the window manager and the windowing system. In the strict sense an X window manager does not directly operate with video hardware, mice, or keyboards, which are the responsibility of the X server. However these elements should actually be the responsibility of the kernel to provide.
Moreover users of the X Window System are able to use many different window managers like, among others, those included in GNOME, KDE. Due to the fact that many window managers are modular, people advert to programs such as Compiz. By way of example Compiz, a 3D compositing window manager, replaces only specific parts of the graphical environment. Numerous components of varying window managers can even be mixed and / or matched. An example therefore are the window decorations from KDE’s KWin that can be used with the desktop and dock components of Gnome.