The Windows shell is the graphical user interface for the desktop in Microsoft Windows, and since Windows 95 has been hosted by Windows Explorer. The Windows shell includes well-known Windows components such as the taskbar and the Start menu. The Windows shell is not the same as a "command-line shell", but the two concepts are related. The Windows shell is also not to be confused with Windows' window manager (the Desktop Window Manager in Windows Vista and forward or the USER subsystem in previous versions), which displays windows and controls how they look. Starting with Windows 8, the legacy Windows Shell has been supplemented by the Modern UI ('Immersive' Shell).
The Windows shell desktop is an array of icons, rendered behind all open windows and taking up the space left by the taskbar. The typical icons displayed on the desktop is as follows:
- Shell folders, usually Documents or the Profile folder, My Computer, Network and Recycle Bin. Since Windows XP, by default the only shell folder displayed on the desktop has been the Recycle Bin.
- Shell launchers, special icons added through a shell extension. Examples include Internet Explorer and older versions of Microsoft Outlook.
- Common shortcuts, or shortcuts that have been installed to the common desktop, usually by a third-party program.
- User shortcuts, or shortcuts in the current user's desktop.
- Desktop files and folders.
Right-clicking on a blank area of the desktop displays a menu which contains, apart from the usual file management and organization options, links to the Personalization and Screen Resolution control panels (Display Properties in earlier versions), and gadget configuration.
The taskbar is divided into three main areas:
- The Start button, which provides access to the Start menu.
- A list of open windows, with the active window's button rendered in a depressed fashion.
- A list of shortcuts to programs for easy access. While previously this had its own area, called the Quick Launch toolbar, it has since been integrated into the list of open programs with the release of Windows 7.
- Deskbands, which are toolbars provided by other programs for easier access to that program's functions.
- The notification area, system icons and clock. Notifications display from a speech bubble which pops out from the relevant notification icon, while system icons provide access to commonly accessed functions like volume control and network status.
Start Menu 
The Start menu consists of a dual-paned menu containing links to various programs and areas of the system.
The left pane of the start menu generally contains software-related shortcuts, including:
- Links to the user's default Internet Browser and Email programs.
- Pinned start menu items.
- The user's most frequently used programs.
- The All Programs menu, which contains shortcuts to programs installed on your computer. Icons can be grouped in submenus called program groups.
- A Search box, which can search for programs, files and control panel settings, as well as replacing the Run dialog and acting as a rudimentary folder explorer.
The right pane contains links to folders and settings, including:
- User account settings, accessed from the square containing the user's profile icon.
- Shell folders, including the user's Profile, Documents, Pictures, and Music folders, the Games Explorer, and My Computer.
- The Control Panel, as well as the Devices and Printers and Default Programs control panels.
- The Shut Down button, with a menu allowing the user to select other options.
Autoplay is a feature introduced in Windows XP that examines newly-inserted removable media for content and displays a dialog containing options related to that media.
Windows 1.0 and 2.0: The MS-DOS Executive 
The first public demonstration of Windows, in 1983, had a simplistic shell called the Session Control Layer, which served as a constantly visible menu at the bottom of the screen. Clicking on Run would display a list of programs that one could launch, and clicking on Session Control would display a list of programs already running so one could switch between them.
When Windows 1.0 shipped in November 1985, it used the MS-DOS Executive as its shell. MS-DOS Executive was a simple file manager that differentiated between files and folders by bold type, since it lacked support for icons, although this made the program somewhat faster than the file manager that came with Windows 3.0. Programs could be launched by double-clicking on them. Files could be filtered for executable type, or by a user-selected wildcard, and the display mode could be toggled between full and compact descriptions. But the file date column was not Y2K compliant.
Windows 2.0 also shipped with MS-DOS Executive as the shell. This version bore little change from its predecessor.
Windows 3.x, NT 3.x: Program Manager 
Windows 3.0, introduced in May 1990, shipped with a new shell, called Program Manager. Based on Microsoft's work with OS/2 1.0's Desktop Manager, Program Manager sorted program shortcuts into groups (although unlike Desktop Manager, these were housed in a single window, in order to show off Microsoft's new Multiple Document Interface.
Program Manager in Windows 3.1 introduced the new Startup group, which Program Manager would check on launch and start any programs it found in it, and wrappable icon titles. Program Manager was also ported to Windows NT 3.1, and retained in Windows NT 3.51.
Windows 95: Windows Explorer replaces Program Manager 
Windows 95 introduced a new shell, hosted in Windows Explorer, the file manager for the operating system. The desktop was now a container for files, folders and system areas such as My Computer, Network Neighborhood, and the Recycle Bin, as well as shortcuts, which were now implemented as files. The taskbar was introduced, with an area consisting of buttons representing open windows, a digital clock, a "notifications area" for background processes and system notifications, and the Start button, which harbored the Start menu. The Start menu contained links to settings, recently-used files and, like Program Manager before it, shortcuts and program groups. Since it provided both shell and file management functions, Explorer replaced both Program Manager and File Manager.
Program Manager was also included in Windows 95 as an "escape hatch", in case the user disliked the new interface. This was included with all versions of Windows up to and including Windows XP Service Pack 1. In SP2 and SP3, PROGMAN.EXE is just an icon library, and it was completely removed from Windows Vista in 2006.
The new shell was also ported to Windows NT, first as the NewShell update for Windows NT 3.51 and then integrated fully into Windows NT 4.0.
Nashville: The Windows Desktop Update 
In early 1996, Netscape announced that the next release of its browser, codenamed "Constellation", would completely integrate with Windows and add a new shell, codenamed "HomePort", which would present the same files and shortcuts no matter which machine a user logged in to. Microsoft started working on a similar Internet Explorer release, codenamed "Nashville". Internet Explorer 4.0 was redesigned and resulted in two products: the standalone IE4 and the Windows Desktop Update, which updated the shell with features such as Active Desktop, Active Channels, Web folders, desktop toolbars such as the Quick Launch bars, ability to minimize windows by clicking their button on the taskbar, HTML-based folder customization, single click launching, image thumbnails, folder infotips, web view in folders, Back and Forward navigation buttons, larger toolbar buttons with text labels, favorites, file attributes in Details view, and an address bar in Windows Explorer, among other features. It also introduced the My Documents shell folder.
Future Windows releases, like Windows 95C (OSR 2.5) and Windows 98, included Internet Explorer 4 and the features of the Windows Desktop Update already built in, and improvements were made in Windows 2000 and Windows Me, such as personalized menus, ability to drag and sort menu items, sort by name function in menus, cascading Start menu special folders, customizable toolbars for Explorer, auto-complete in Windows Explorer address bar and Run box, displaying comments in file shortcuts as tooltips, advanced file type association features, extensible columns in Details view (IColumnProvider interface), icon overlays, places bar in common dialogs, high-color notification area icons and a search pane in Explorer.
The 2000s: Taskbar and Start Menu Improvements 
Windows XP introduced a new Start Menu, with shortcuts to shell locations on the right and a list of most frequently used applications on the left. It also grouped taskbar buttons from the same program if the taskbar got too crowded, and hid notification icons if they had not been used for a while. For the first time, Windows XP hid most of the shell folders from the desktop by default, leaving only the recycle bin (although the user could get them back if they desired). Windows XP also introduced numerous other shell enhancements.
In the early days of the Longhorn project, an experimental sidebar, with plugins similar to taskbar plugins and a notifications history was built into the shell. However, when Longhorn was reset this was ditched in favor of a separate program that provided Web-enabled gadgets, replacing Active Desktop.
Windows Vista introduced to the shell a searchable Start menu and live taskbar previews. It also introduced a redesigned Alt-Tab switcher, also with live previews. Windows 7 added 'pinned' shortcuts and 'jump lists' to the taskbar, and automatically grouped program windows into one icon (although this could be reversed.) The Windows 7 shell also re-absorbed the responsibility of rendering gadgets.
Shell replacements 
Windows supports the ability to replace the Windows shell with another program. There also exists a number of third party shells designed to be used in place of the standard Windows shell.
See also 
- Phil Lemmons (December 1983). "Microsoft Windows: A Mouse With Modest Requirements". BYTE Magazine. Retrieved 2011-05-07.
- "New Features in Windows 3.1". Microsoft Corporation. Retrieved 2011-05-07.
- Raymond Chen (October 2010). "Windows Confidential: Leftovers from Windows 3.0". TechNet Magazine. Retrieved 2011-05-07.
- Paul Thurrott (March 3, 1997). "Netscape Constellation beta due in June". Windows IT Pro. Retrieved 2011-05-07.
- Jon Gordon (December 24, 2008). "Why Google Loves Chrome: Netscape Constellation". Retrieved 2011-05-07.
- Tim Anderson (April 4, 2010). "Jewels from the loft: launch of Delphi, Netscape’s Constellation, HTML to die, Longhorn for developers". Retrieved 2011-05-07.
- "What Is Server Core?". Retrieved 30 October 2011.
- "Understanding Windows Server 2008 Server Core".
- "Different Shells for Different Users". Retrieved 18 March 2013.