Intuition is the windowing system

Windowing system

A windowing system is a component of a graphical user interface , and more specifically of a desktop environment, which supports the implementation of window managers, and provides basic support for graphics hardware, pointing devices such as mice, and keyboards...

 and user interface (UI) engine of AmigaOS

AmigaOS

AmigaOS is the default native operating system of the Amiga personal computer. It was developed first by Commodore International, and initially introduced in 1985 with the Amiga 1000...

. It was developed almost entirely by RJ Mical. Intuition should not be confused with Workbench

Workbench (AmigaOS)

-Overview:Commodore named their Amiga computer's first operating system Workbench 1.0 and continued with the Workbench name until version 3.1, when it was changed to AmigaOS, prompted by Apple renaming their propriety OS from "System" to "MacOS"...

, the AmigaOS spatial file manager

Spatial file manager

In computing, a spatial file manager is a file manager that uses a spatial metaphor to represent files and folders as if they are real physical objects.-Concepts:The base requirements of a spatial file manager are:...

, which relies on Intuition for handling windows and input events.

Users may remember the initial releases for their garish blue/orange/white/black palettes. This was intentional: in a time before cheap high-quality video monitors, the Amiga team tested output on the worst television

Television

Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...

s they could find, with the goal of obtaining the best possible contrast under these worst-case conditions.

Intuition is the internal widget and graphics system. It is not implemented primarily as an application-managed graphics library (as most systems, following Xerox

Xerox

Xerox Corporation is an American multinational document management corporation that produced and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies...

' design, have done), but rather as a separate task that maintains the state of all the standard UI elements independently from the application. This makes it singularly responsive because UI gadgets are live even when the application is busy. The Intuition task is driven by user events through the mouse

Mouse (computing)

In computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons...

, keyboard

Computer keyboard

In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...

, and other input devices. It also arbitrates collisions of the mouse pointer and icons

Icon (computing)

A computer icon is a pictogram displayed on a computer screen and used to navigate a computer system or mobile device. The icon itself is a small picture or symbol serving as a quick, intuitive representation of a software tool, function or a data file accessible on the system. It functions as an...

 and control of "animated icons".

Due to a mistake made by the Commodore sales department, the first floppies

Floppy disk

A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

 of AmigaOS

AmigaOS

AmigaOS is the default native operating system of the Amiga personal computer. It was developed first by Commodore International, and initially introduced in 1985 with the Amiga 1000...

 which were released with Amiga 1000

Amiga 1000

The A1000, or Commodore Amiga 1000, was Commodore's initial Amiga personal computer, introduced on July 23, 1985 at the Lincoln Center in New York City....

 named the whole operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

 (OS) "Workbench". Since then, users and CBM itself referred to "Workbench" as the nickname for the whole AmigaOS (including Amiga DOS, Extras, etc.). This common consent ended with release of version 2.0 of AmigaOS, which re-introduced proper names to the installation floppies of AmigaDOS

AmigaDOS

AmigaDOS is the disk operating system of the AmigaOS, which includes file systems, file and directory manipulation, the command-line interface, and file redirection....

, Workbench, Extras, etc.).

Workbench is also used on the Amiga as a metaphor for their own standard of "desktop

Desktop metaphor

The desktop metaphor is an interface metaphor which is a set of unifying concepts used by graphical user interfaces to help users more easily interact with the computer. The desktop metaphor treats the monitor of a computer as if it is the user's desktop, upon which objects such as documents and...

" as opposed to others, such as "Macintosh Finder

Macintosh Finder

The Finder is the default file manager used on Mac OS and Mac OS X operating systems; it is responsible for the overall user-management of files, disks, network volumes and the launching of other applications...

". Workbench itself is another library or process. Rumors said that this concept of modularity was invented by Commodore to treat Workbench as a window amongst the others in the desktop, in order to avoid reprisal from Apple

Apple Computer

Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...

. But this can only be considered a rumor, as all patents on windowed GUIs were property of Xerox

Xerox

Xerox Corporation is an American multinational document management corporation that produced and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies...

 at that time.

Early versions of AmigaOS did treat the Workbench as just another window on top of a blank screen; but this is due to the ability of AmigaOS to have invisible screens with a chromakey or a genlock

Genlock

Genlock is a common technique where the video output of one source, or a specific reference signal from a signal generator, is used to synchronize other television picture sources together. The aim in video and digital audio applications is to ensure the coincidence of signals in time at a...

, even without losing the visibility of Workbench itself. In later AmigaOS versions Workbench could be set as a borderless desktop.

Amiga users were also able to boot

Booting

In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...

 their computer into a command line interface (CLI), also known as shell

Shell (computing)

A shell is a piece of software that provides an interface for users of an operating system which provides access to the services of a kernel. However, the term is also applied very loosely to applications and may include any software that is "built around" a particular component, such as web...

. This was a keyboard-based environment without the Workbench GUI. Later they could invoke it with the CLI/SHELL command LoadWB which performs the task to load Workbench GUI.

Like most GUIs of the day, Amiga's Intuition followed Xerox's lead anteceding solutions, but pragmatically, a command line interface was also included and it extended the functionality of the platform. Later releases added more improvements, like support for high-color Workbench screens and 3D aspect. Replacement desktops were also made available, such as Directory Opus Magellan

Directory Opus

Directory Opus is a popular file manager program, originally written for the Amiga computer system in the early to mid 1990s...

, or Scalos

Scalos

Scalos is the name of a commercial desktop replacement for the Workbench Amiga original GUI, based on a subset of APIs and its own front-end window manager of the same name....

 interface.

Other GUI toolkits

The use of improved, third party GUI engines became common amongst users who preferred more attractive interfaces—such as Magic User Interface

Magic User Interface

The Magic User Interface is an object-oriented system by Stefan Stuntz to generate and maintain graphical user interfaces. With the aid of a preferences program, the user of an application has the ability to customize the outfit according to personal taste....

 (MUI), and ReAction

ReAction GUI

ReAction GUI it is the name of the widget toolkit engine that is used in AmigaOS 3.5-4.1.It is an evolution of ClassACT, which is an object oriented system of classes that enhanced the aspect of the Workbench 2.0 GUI of AmigaOS.- History :...

. These Object Oriented graphic engines driven by "classes" of graphic objects and functions were then standardized into the Amiga environment and changed Amiga Workbench to a complete and modern guided interface, with new standard gadgets, animated buttons, true 24bit-color icons, increased use of wallpapers for screens and windows, alpha channel, transparencies and shadows as any modern GUI requires.

MUI and similar systems abandoned the separation of the User Interface between the application (which specified gadgets to be displayed) and the Intuition task (which actually managed gadgets for all applications, even when they were busy).

Heirs of Workbench are nowadays: Ambient

Ambient desktop

Ambient is a MUI-based desktop environment for MorphOS. Its development was started in 2001 by David Gerber. Its main goals were that it should be simple and fast...

 for MorphOS

MorphOS

MorphOS is an Amiga-compatible computer operating system. It is a mixed proprietary and open source OS produced for the Pegasos PowerPC processor based computer, PowerUP accelerator equipped Amiga computers, and a series of Freescale development boards that use the Genesi firmware, including the...

, Scalos

Scalos

Scalos is the name of a commercial desktop replacement for the Workbench Amiga original GUI, based on a subset of APIs and its own front-end window manager of the same name....

, Workbench for AmigaOS 4

AmigaOS 4

AmigaOS 4, , is a line of Amiga operating systems which runs on PowerPC microprocessors. It is mainly based on AmigaOS 3.1 source code, and partially on version 3.9 developed by Haage & Partner...

 and Wanderer for AROS

Aros

Aros may refer to:*Aros , a river in J. R. R. Tolkien's Middle-earth legendarium*AROS Research Operating System, a free software implementation of AmigaOS* Aros, the original Viking name of Aarhus, the second largest city in Denmark...

.
There is a brief article on Ambient and descriptions of MUI icons, menus and gadgets here (aps.fr) and images of Zune

Zune (GUI toolkit)

Zune is an object-oriented GUI toolkit which is part of the AROS project and nearly a clone, at both an API and look and feel level, of Magic User Interface , a well-known Amiga shareware product by Stefan Stuntz....

 stay at main AROS site.

A new object-oriented toolkit for all Amiga-like platforms (AmigaOS, MorphOS, AROS), Feelin,was introduced in 2005, and makes extensive use of XML

XML

Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....

 guidelines. It uses its own memory management system, and its memory-pools system shares the embedded OS's semaphores

Semaphore (programming)

In computer science, a semaphore is a variable or abstract data type that provides a simple but useful abstraction for controlling access by multiple processes to a common resource in a parallel programming environment....

. Feelin also features a non-centralized ID allocation system, a crash-free object invocation mechanism, and an advanced logging system. Details and images on Feelin can be found at its website.