In graphical computing, a desktop environment (DE) offers a complete graphical user interface (GUI) solution to operate a computer. The name is derived from the desktop metaphor used by most of these interfaces. A DE provides icons, toolbars, applications, applets, and abilities like drag and drop. As a whole, the particularities of design and function of a desktop environment endow it with a distinctive look and feel.
On systems running the X Window System (typically Unix systems), the desktop environment is much more flexible. In this context, a DE typically consists of a window manager, a set of themes, and programs and libraries for managing the desktop. All of these individual modules can be exchanged and individually configured to achieve a unique combination, but most desktop environments provide a default configuration that requires minimal user input.
Well-known desktop environments examples , include GNOME, KDE, CDE and Xfce.
A window manager is software that controls the placement and appearance of application windows under the X Window System, a graphical user interface on Unix systems that enables a user to interact with a number of application programs simultaneously. Each one typically has its own independent window, and when a window manager is available, interaction between the X server and its clients is redirected through the window manager.
The user can choose between various third-party window managers, which differ from one another in several ways, including:
* customizability of appearance and functionality:
o textual menus used to start programs and/or change options
o docks and other graphical ways to start programs
o multiple desktops and virtual desktops (desktops larger than the physical monitor size), and pagers to switch between them
* consumption of memory and other system resources
* degree of integration with a desktop environment, which provides a more complete interface to the operating system, and provides a range of integrated utilities and applications.
Operating system shell - Wikipedia, the free encyclopedia
An operating system shell is a shell for an operating system; it is a program that presents an interface to various operating system functions and services. The shell is so called because it is an outer layer of interface between the user and the innards of the operating system (the kernel).
Operating system shells generally fall into one of two categories: command line and graphical. Command line shells provide a command line interface (CLI) to the operating system, while graphical shells provide a graphical user interface (GUI).
The Linux Wikipedia is a great place to find general information.