Windows 1.0, released in 1985, features a horizontal bar located at the bottom of the screen where running programs reside when minimized (referred to as "iconization" at the time), represented by icons. A window can be minimized by double-clicking its title bar, dragging it onto an empty spot on the bar, or by issuing a command from one of its menus. A minimized window is restored by double-clicking its icon or dragging the icon out of the bar.
The bar features multiple slots for icons and expands vertically to provide with more rows as more slots are needed. Its color is the same as that of the screen background, which can be customized. Minimized windows can be freely placed in any of the empty slots. Program windows cannot overlap the bar unless maximized.
Appearance of the bar used for holding minimized windows in Windows 1.0
Another early implementation can be seen in the Arthur operating system from Acorn Computers. It is called the icon bar and remains an essential part of Arthur's succeeding RISC OS operating system. The icon bar holds icons which represent mounted disc drives and RAM discs, running applications and system utilities. These icons have their own context-sensitive menus and support drag and drop behaviour.
Appearance of Acorn's icon bar in 1987 under Arthur, after launching a number of devices and applications
AmigaOS featured various third party implementations of taskbar concept, and this inheritance is present also in its successors. For example, AmiDOCK, born as third-party utility, has then been integrated into AmigaOS 3.9 and AmigaOS 4.0. The AROS operating system has its version of Amistart that is provided with the OS and free to be installed by users, while MorphOS has been equipped with a dock utility just like in AmigaOS or Mac OS X.
The default settings for the taskbar in Microsoft Windows place it at the bottom of the screen and includes from left to right the Start menu button, Quick Launch bar, taskbar buttons, and notification area. The Quick Launch toolbar was added with the Windows Desktop Update and is not enabled by default in Windows XP. Windows 7 removed the Quick Launch feature in favor of pinning applications to the taskbar itself. On Windows 8, the Start button has been removed in favor of a hotspot located in the bottom-left corner of the screen.
The taskbar was originally developed as a feature of Windows 95, but it was based on a similar user interface feature called the tray that was developed as part of Microsoft's Cairo project.
With the release of Windows XP, Microsoft changed the behavior of the taskbar to take advantage of Fitts's law by removing a border of pixels surrounding the Start button which did not activate the menu, allowing the menu to be activated by clicking directly in the corner of the screen.
The taskbar in Windows 7 hides application names in favor of large icons that can be "pinned" to the taskbar even when not running. Unlike Windows Vista and Windows XP's notification area, users have a choice to show all their notifications or get a small pop-up window, showing the user notifications without expanding.
A standard Windows XP taskbar with multiple tasks running. Note the Quick Launch toolbar, introduced in Windows 98. When the notification area is full, it can be expanded.
The first implementation of the Windows taskbar in Windows 95.
The Windows shell places a taskbar button on the taskbar whenever an application creates an unowned window: that is, a window that doesn't have a parent and that is created according to normal Windows user interface guidelines. Typically all Single Document Interface applications have a single taskbar button for each open window, although modal windows may also appear there.
Windows Me added an option to disable moving or resizing the taskbar.
Windows XP introduced taskbar grouping, which can group the taskbar buttons of several windows from the same application into a single button. This button pops up a menu listing all the grouped windows when clicked. This keeps the taskbar from being overcrowded when many windows are open at once.
Windows Vista introduced window previews which show thumbnail views of the application in real-time. This capability is provided by the Desktop Window Manager. Start menu tooltip no longer says "Click here to begin". Now, says simply "Start".
Windows 7 introduced jumplists which are menus that provide shortcuts to recently opened documents, frequently opened documents, folders paths (in case of Windows Explorer), or various options (called Tasks) which apply to that specific program or pinned website shortcut. Jump lists appear when the user right-clicks on an icon in the taskbar or drags the icon upwards with the mouse left click. Recent and frequent files and folders can be pinned inside the jump list.
Windows 7 introduced the ability to pin applications to the taskbar so that buttons for launching them appear when they are not running. Previously, the Quick launch was used to pin applications to the taskbar; however, running programs appeared as a separate button.
Deskbands are minimized functional, long-running programs, such as Windows Media Player. Programs that minimize to deskbands aren't displayed in the taskbar.
The notification area is the portion of the taskbar that displays icons for system and program features that have no presence on the desktop as well as the time and the volume icon. It contains mainly icons that show status information, though some programs, such as Winamp, use it for minimized windows. By default, this is located in the bottom-right of the primary monitor (or bottom-left on languages of Windows that use right-to-left reading order), or at the bottom of the taskbar if docked vertically. The clock appears here, and applications can put icons in the notification area to indicate the status of an operation or to notify the user about an event. For example, an application might put a printer icon in the status area to show that a print job is under way, or a display driver application may provide quick access to various screen resolutions. The notification area is commonly referred to as the system tray, which Microsoft states is wrong, although the term is sometimes used in Microsoft documentation, articles, software descriptions, and even applications from Microsoft such as Bing Desktop. Raymond Chen suggests the confusion originated with systray.exe, a small application that controlled some icons within the notification area in Windows 95. The notification area is also referred to as the status area by Microsoft.
In older versions of Windows the notification area icons were limited to 16 colors. Windows Me added support for high color notification area icons.
Starting with Windows XP, the user can choose to always show or hide some icons, or hide them if inactive for some time. A button allows the user to reveal all the icons.
Starting with Windows Vista, the taskbar notification area is split into two areas; one reserved for system icons including clock, volume, network and power. The other is for applications.
Since the Windows 95 Desktop Update, the Quick Launch bar featured Show desktop as one of its default shortcuts, which automatically minimizes all opened applications. On Windows 7, a dedicated Show desktop button was placed to the right of the notification area. With the "Peek" option enabled, hovering over the button hides all opened windows to expose the desktop (leaving outlines of them on-screen).
The Windows taskbar can be modified by users in several ways. The position of the taskbar can be changed to appear on any edge of the primary display. Up to and including Windows Server 2008, the taskbar is constrained to single display, although third-party utilities such as UltraMon allow it to span multiple displays. When the taskbar is displayed vertically on versions of Windows prior to Windows Vista, the Start menu button will only display the text "Start" or translated equivalent if the taskbar is wide enough to show the full text. However, the edge of the taskbar (in any position) can be dragged to control its height (width for a vertical taskbar); this is especially useful for a vertical taskbar to show window titles next to the window icons.
Users can resize the height (or width when displayed vertically) of the taskbar up to half of the display area. To avoid inadverdent resizing or repositioning of the taskbar, Windows XP and later lock the taskbar by default. When unlocked, "grips" are displayed next to the movable elements which allow grabbing with the mouse to move and size. These grips slightly decrease amount of available space in the taskbar.
The taskbar as a whole can be hidden until the mouse pointer is moved to the display edge, or has keyboard focus. The Windows 7+ taskbar does not allow pinning any arbitrary folder to the taskbar, it gets pinned instead to the jumplist of a pinned Explorer shortcut, however third party utilities such as Winaero's Taskbar Pinner can be used to pin any type of shortcut to the Taskbar.
Other toolbars, known as "Deskbands", may be added to the taskbar. Windows includes the following deskbands but does not display them by default (except the Quick Launch toolbar in certain versions and configurations).
Links. Shortcuts to items located in the user's Links folder. Usually shortcuts to internet sites.
Tablet PC Input Panel. Contains a button to show the Tablet PC input panel for ink text entry.
Desktop. Contains shortcuts to items contained on the user's desktop. Since the taskbar is always shown, this provides easy access to desktop items without having to minimize applications.
Quick Launch. Contains shortcuts to Internet Explorer, email applications and a link to display the desktop. Windows Vista adds a link to the Flip 3D feature.
Language. Contains shortcuts to quickly change the desired language for the keyboard to follow.
In addition to deskbands, Windows supports "Application Desktop Toolbars" (also called "appbands") that supports creating additional toolbars that can dock to any side of the screen, and cannot be overlaid by other applications.
Users can add additional toolbars that display the contents of folders. The display for toolbars that represent folder items (such as Links, Desktop and Quick Launch) can be changed to show large icons and the text for each item. Prior to Windows Vista, the Desktop Toolbars could be dragged off the taskbar and float independently, or docked to a display edge. Windows Vista greatly limited, but did not eliminate the ability to have desktop toolbar not attached to the taskbar.Windows 7 has deprecated the use of Floating Deskbands altogether: they only appear pinned into the Taskbar.
Upon opening the Taskbar properties on Windows 95 and Windows 98 whilst holding down the CTRL key, an extra tab for DeskBar Options is shown, but no part of it can be used. The DeskBar option was a feature that was never included within these versions of Windows.
The Dock, as featured in Mac OS X and its predecessor NeXTSTEP, is also a kind of taskbar. The Mac OS X Dock is application-oriented instead of window-oriented. Each running application is represented by one icon in the Dock regardless of how many windows it has on screen. A textual menu can be opened by right-clicking on the dock icon that gives access to an application's windows, among other functions determined by the app. Minimized windows also appear in the dock, in the rightmost section, represented by a graphical thumbnail. The trash can is also represented in the Dock, as a universal metaphor for deletion. For example, dragging selected text to the trash should remove the text from the document and create a clipping file in the trash.
The right side of Mac OS X's Menu bar also contains several notification widgets and quick access functions, called Menu extras.
In K Desktop Environment 3 and earlier, the taskbar is run by the Kicker program, which shows rectangular panels that can contain applets, one of which is the taskbar. Applets can be arbitrarily relocated, for instance, the notification area can be moved away from the taskbar. The bar can be placed not only at the bottom, but also at the top or (vertically) at the left or the right and its size can be altered (from 24 to 256 pixels), as well as the length in percent of the screen size. And several other bars with various specific functions can be added in different locations, e.g., one bar at the left and one at the right or even overlapping (one fixed and one with automatic hiding). Since KDE Plasma Workspaces, the taskbar is implemented as a Plasma widget.
Standard layout in K Desktop Environment 3.5.
Plasma panel being resized in KDE Plasma Workspaces 4.3
Similarly, GNOME 2 used its own type of taskbar, known as panels (the program responsible for them is therefore called gnome-panel). By default, GNOME 2 usually contains two full-width panels at the top and bottom of the screen. The top panel usually contains navigation menus labelled Applications, Places, and System in that order. These menus hold links to common applications, areas of the file system, and system preferences and administration utilities, respectively.
Default top panel in Ubuntu
Default bottom panel in Ubuntu
The top panel usually contains a clock and notification area, while the bottom panel contains buttons for navigating between virtual desktops, the window list proper, and a button which minimizes all windows (similarly to Windows' Show desktop button). The contents of panels are handled by widgets called panel applets, which can consist of application shortcuts, search tools, or other tools. The contents of the panels can be moved, removed, or configured in other ways.
GNOME 3.0, April 2011
On GNOME 3, panels are replaced by GNOME Shell, which consists of a bar across the top of the screen with an Activities button on the left, a clock in the centre, and a notification area on the right. GNOME Shell does not contain a traditional taskbar, and windows cannot be minimized; users can manage windows, virtual desktops, and launch applications (from either a "Dash" on the side of the screen, or by searching) from Activities Overview, which is displayed by clicking on the Activities button. GNOME 3.8 introduces Classic Mode, which re-implements certain aspects of GNOME 2's desktop as GNOME Shell extensions.