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X Window System



 
 
The X Window System (commonly X or X11) is a computer
Computing

Computing is usually defined as the activity of using and developing computer technology, computer hardware and computer software. It is the computer-specific part of information technology....
 software system and network protocol that provides a graphical user interface
Graphical user interface

A graphical user interface is a type of user interface which allows people to human-computer interaction such as computers; hand-held devices such as MP3 Players, Portable Media Players or Gaming devices; household appliances and office equipment....
 (GUI) for networked computers. It implements the X display protocol
X Window System protocols and architecture

In computing, the X Window System is a computer network-transparent windowing system for raster graphics displays. This article details the protocols and technical structure of X11....
 (invented by Hewlett Packard) and provides windowing
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....
 on raster graphics
Raster graphics

In computer graphics, a raster graphics image or bitmap, is a data structure representing a generally Rectangle grid of pixels, or points of color, viewable via a Computer display, paper, or other display medium....
 (bitmap) computer displays and manages keyboard
Keyboard (computing)

In computing, a keyboard is an input device, partially modeled after the Typewriter#Keyboard layout, which uses an arrangement of buttons or Push-button, which act as mechanical levers or electronic switches....
 and pointing device
Pointing device

A pointing device is an input interface that allows a user to input spatial data to a computer. Computer-aided design systems and graphical user interfaces allow the user to control and provide data to the computer using physical Mouse gesture ? point, click, and drag ? for example, by moving a hand-held Mouse across the surface of the...
 control functions. In its standard distribution, it is a complete, albeit simple, display and human interface solution, but also delivers a standard toolkit and protocol stack for building graphical user interface
Graphical user interface

A graphical user interface is a type of user interface which allows people to human-computer interaction such as computers; hand-held devices such as MP3 Players, Portable Media Players or Gaming devices; household appliances and office equipment....
s on most Unix-like
Unix-like

A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
 operating systems and OpenVMS
OpenVMS

OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is the name of a high-end computer server operating system that runs on the VAX and DEC Alpha families of computers, developed by Digital Equipment Corporation of Maynard, Massachusetts, Massachusetts , and most recently on Hewlett-Packard systems built around the In...
, and has been ported
Porting

In computer science, porting is the process of adapting software so that an executable Computer program can be created for a computing environment that is different from the one for which it was originally designed ....
 to many other contemporary general purpose operating systems. Desktop environments, such as GNOME
Gnome

A gnome is a mythical creature characterized by its extremely small size and wiktionary:subterranean lifestyle. The word gnome is derived from the New Latin gnomus....
, KDE
KDE

KDE is a free software project based around its flagship product, a desktop environment for Unix-like systems. The goal of the project is to provide basic desktop functions and applications for daily needs as well as tools and documentation for developers to write stand-alone applications for the system....
, and Xfce
Xfce

Xfce is a free software desktop environment for Unix and other Unix-like platforms, such as Linux, Solaris and BSD. It aims to be fast and lightweight, while still being visually appealing and easy to use....
, use the X Window System.

X provides the basic framework, or primitives, for building such GUI environments: drawing and moving window
Window (computing)

In computing, a window is a visual area, usually rectangular in shape, containing some kind of user interface, displaying the output of and allowing input for one of a number of simultaneously running computer processes....
s on the screen and interacting with a mouse and/or keyboard.






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Encyclopedia


The X Window System (commonly X or X11) is a computer
Computing

Computing is usually defined as the activity of using and developing computer technology, computer hardware and computer software. It is the computer-specific part of information technology....
 software system and network protocol that provides a graphical user interface
Graphical user interface

A graphical user interface is a type of user interface which allows people to human-computer interaction such as computers; hand-held devices such as MP3 Players, Portable Media Players or Gaming devices; household appliances and office equipment....
 (GUI) for networked computers. It implements the X display protocol
X Window System protocols and architecture

In computing, the X Window System is a computer network-transparent windowing system for raster graphics displays. This article details the protocols and technical structure of X11....
 (invented by Hewlett Packard) and provides windowing
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....
 on raster graphics
Raster graphics

In computer graphics, a raster graphics image or bitmap, is a data structure representing a generally Rectangle grid of pixels, or points of color, viewable via a Computer display, paper, or other display medium....
 (bitmap) computer displays and manages keyboard
Keyboard (computing)

In computing, a keyboard is an input device, partially modeled after the Typewriter#Keyboard layout, which uses an arrangement of buttons or Push-button, which act as mechanical levers or electronic switches....
 and pointing device
Pointing device

A pointing device is an input interface that allows a user to input spatial data to a computer. Computer-aided design systems and graphical user interfaces allow the user to control and provide data to the computer using physical Mouse gesture ? point, click, and drag ? for example, by moving a hand-held Mouse across the surface of the...
 control functions. In its standard distribution, it is a complete, albeit simple, display and human interface solution, but also delivers a standard toolkit and protocol stack for building graphical user interface
Graphical user interface

A graphical user interface is a type of user interface which allows people to human-computer interaction such as computers; hand-held devices such as MP3 Players, Portable Media Players or Gaming devices; household appliances and office equipment....
s on most Unix-like
Unix-like

A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
 operating systems and OpenVMS
OpenVMS

OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is the name of a high-end computer server operating system that runs on the VAX and DEC Alpha families of computers, developed by Digital Equipment Corporation of Maynard, Massachusetts, Massachusetts , and most recently on Hewlett-Packard systems built around the In...
, and has been ported
Porting

In computer science, porting is the process of adapting software so that an executable Computer program can be created for a computing environment that is different from the one for which it was originally designed ....
 to many other contemporary general purpose operating systems. Desktop environments, such as GNOME
Gnome

A gnome is a mythical creature characterized by its extremely small size and wiktionary:subterranean lifestyle. The word gnome is derived from the New Latin gnomus....
, KDE
KDE

KDE is a free software project based around its flagship product, a desktop environment for Unix-like systems. The goal of the project is to provide basic desktop functions and applications for daily needs as well as tools and documentation for developers to write stand-alone applications for the system....
, and Xfce
Xfce

Xfce is a free software desktop environment for Unix and other Unix-like platforms, such as Linux, Solaris and BSD. It aims to be fast and lightweight, while still being visually appealing and easy to use....
, use the X Window System.

X provides the basic framework, or primitives, for building such GUI environments: drawing and moving window
Window (computing)

In computing, a window is a visual area, usually rectangular in shape, containing some kind of user interface, displaying the output of and allowing input for one of a number of simultaneously running computer processes....
s on the screen and interacting with a mouse and/or keyboard. X does not mandate the user interface
User interface

The user interface is the aggregate of means by which people—the User s—Interaction with the system—a particular machine, device, computer program or other complex tools....
 — individual client programs handle this. As such, the visual styling of X-based environments varies greatly; different programs may present radically different interfaces. X is built as an additional application layer on top of the operating system kernel.

Unlike previous display protocols, X was specifically designed to be used over network
Computer network

A computer network is a group of interconnected computers. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of some types and categories and also presents the basic components of a network....
 connections rather than on an integral or attached display device. X features network transparency
Network transparency

Network Transparency in its most general sense refers to the ability of a protocol to transmit data over the network in a manner which is Transparency_%28computing%29 to those using the applications that are using the protocol....
: the machine where an application program (the client application) runs can differ from the user's local machine (the display server).

X originated at MIT
Massachusetts Institute of Technology

The Massachusetts Institute of Technology is a private university research university located in Cambridge, Massachusetts, Massachusetts, United States....
 in 1984. The current protocol version, X11, appeared in September 1987. The X.Org Foundation
X.Org Foundation

The X.Org Foundation is the organization holding the stewardship for the development of the X Window System. It was founded on 22 January 2004....
 leads the X project, with the current open source implementation, X.org Server
X.Org Server

The X.Org Server is the X server in the official reference implementation of the X Window System. The current stable release is 1.6.0, which is part of X11R7.5, and was released on 25 February 2009....
, available as free software
Free software

Free Software or software libre is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with minimal restrictions only to ensure that further recipients can also do these things and to prevent consumer-facing hardware...
 under the MIT License
MIT License

The MIT License is a free software license originating at the Massachusetts Institute of Technology , used by the MIT X Consortium.It is a Permissive_free_software_licence license, meaning that it permits reuse within proprietary software on the condition that the license is distributed with that software....
 and similar permissive licences.

Design

X uses a client-server
Client-server

The client-server software architecture model distinguishes client systems from server systems, which communicate over a computer network. A client-server application is a distributed system comprising both client and server software....
 model: an X server communicates with various client programs. The server accepts requests for graphical output (windows) and sends back user input (from keyboard, mouse, or touchscreen). The server may function as:
  • an application displaying to a window of another display system
  • a system program controlling the video output of a PC
    Personal computer

    A personal computer is any general-purpose computer whose original sales price, size, and capabilities make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator....
  • a dedicated piece of hardware.


This client-server terminology — the user's terminal as the "server", the remote or local applications as the "clients" — often confuses new X users, because the terms appear reversed. But X takes the perspective of the program, rather than that of the end-user or of the hardware: the local X display provides display services to programs, so it acts as a server; any remote program uses these services, thus it acts as a client.

The communication protocol between server and client operates network
Computer network

A computer network is a group of interconnected computers. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of some types and categories and also presents the basic components of a network....
-transparently: the client and server may run on the same machine or on different ones, possibly with different architectures
Computer architecture

Computer architecture in computer engineering is the conceptual design and fundamental operational structure of a computer system. It is a blueprint and functional description of requirements and design implementations for the various parts of a computer, focusing largely on the way by which the central processing unit performs internally an...
 and operating system
Operating system

An operating system is an interface between hardware and applications; it is responsible for the management and coordination of activities and the sharing of the limited resources of the computer....
s, but they run the same in either case. A client and server can even communicate secure
Computer security

Computer security is a branch of technology known as information security as applied to computers. The objective of computer security can include protection of information from theft or corruption, or the preservation of availability, as defined in the security policy....
ly over the Internet
Internet

The Internet is a global network of interconnected computers, enabling users to share information along multiple channels. Typically, a computer that connects to the Internet can access information from a vast array of available server and other computers by moving information from them to the computer's local memory....
 by tunneling
Tunneling protocol

The term tunneling protocol is used to describe when one network protocol called the payload protocol is encapsulation within a different delivery protocol....
 the connection over an encrypted network session.

An X client itself may contain an X server having display of multiple clients. This is known as "X nesting". Open-source clients such as Xnest
Xnest

Xnest is an X Window System server that shows its output in a Window . In other words, Xnest opens a window that works like another screen in which the user can open windows, etc....
 and Xephyr
Xephyr

Xephyr is a KDrive based X server which targets a window on a host X Server as its framebuffer. Unlike Xnest it supports modern X extensions such as Composite, Damage, randr etc....
 support such X nesting.

To use a client program on a remote machine, the user does the following:
  • On the local machine, open a terminal window
    Terminal emulator

    A terminal emulator, terminal application, term, or tty for short, is a program that emulates a "dumb" video Computer terminal within some other display architecture....
  • use telnet
    TELNET

    Telnet is a network protocol used on the Internet or Local Area Network connections. It was developed in 1969 beginning with RFC 15 and standardized as Internet Engineering Task Force STD 8, one of the first Internet standards....
     or ssh
    Secure Shell

    Secure Shell or SSH is a network protocol that allows data to be exchanged using a secure channel between two networked devices. Used primarily on Linux and Unix based systems to access shell accounts, SSH was designed as a replacement for TELNET and other Computer security remote Shell s, which send information, notably passwords, in...
     to connect to the remote machine
  • request local display/input service (e.g., export DISPLAY=[user's machine]:0 if not using SSH with X tunneling enabled)
The remote X client will then make a connection to the user's local X server, providing display and input to the user.

Alternatively, the local machine may run a small program that connects to the remote machine and starts the client application.

Practical examples of remote clients include:
  • administering a remote machine graphically
  • running a computationally intensive simulation on a remote Unix machine and displaying the results on a local Windows desktop machine
  • running graphical software on several machines at once, controlled by a single display, keyboard and mouse.


Principles

In 1984, Bob Scheifler
Bob Scheifler

Robert William Scheifler is a computer scientist. He is most notable for leading the development of the X Window System from the project's inception in 1984 until the closure of the MIT X Consortium in 1996....
 and Jim Gettys
Jim Gettys

Jim Gettys is a computer programmer. Until January 2009, he was the Vice President of Software at the One Laptop per Child project, working on the software for the OLPC XO-1....
 set out the early principles of X:

  • Do not add new functionality unless an implementor cannot complete a real application without it.
  • It is as important to decide what a system is not as to decide what it is. Do not serve all the world's needs; rather, make the system extensible so that additional needs can be met in an upwardly compatible fashion.
  • The only thing worse than generalizing from one example is generalizing from no examples at all.
  • If a problem is not completely understood, it is probably best to provide no solution at all.
  • If you can get 90 percent of the desired effect for 10 percent of the work, use the simpler solution. (See also Worse is better
    Worse is better

    Worse is better, also called the New Jersey style was conceived by Richard P. Gabriel to describe the dynamics of software acceptance but it has broader application....
    .)
  • Isolate complexity as much as possible.
  • Provide mechanism rather than policy. In particular, place user interface policy in the clients' hands.


The first principle was modified during the design of X11 to: "Do not add new functionality unless you know of some real application that will require it."

X has largely kept to these principles since. The sample implementation is developed with a view to extension and improvement of the implementation, whilst remaining almost entirely compatible with the original 1987 protocol.

User interfaces

X is primarily a protocol and graphics primitives definition and it deliberately contains no specification for application user interface
User interface

The user interface is the aggregate of means by which people—the User s—Interaction with the system—a particular machine, device, computer program or other complex tools....
 design, such as button
Button (computing)

In computing, a button is a user interface element that provides the user a simple way to trigger an event , like searching for a query at a search engine, or to interact with dialog boxes, like confirming an action....
, menu
Menu (computing)

In computing and telecommunications, a menu is a list of commands presented to an operator by a computer or communications system. They may be thought of as shortcuts to frequently used commands that avoid the operator having to have a detailed knowledge or recall of syntax....
, or window title bar
Title bar

In computing, the title bar consists of that part of a Window where the title of the window appears. Most graphical operating systems and window managers position the title bar at the top of the application software window as a horizontal bar....
 styles. Instead, application software – such as window manager
Window manager

A window manager is computer software that controls the placement and appearance of window within a windowing system in a graphical user interface....
s, GUI widget toolkit
Widget toolkit

A widget toolkit, widget library, or GUI toolkit is a set of GUI widget for use in designing applications with graphical user interfaces ....
s and desktop environment
Desktop environment

In graphical computing, a desktop environment commonly refers to a style of graphical user interface that is based on the desktop metaphor which can be seen on most modern personal computers today....
s, or application-specific graphical user interfaces - define and provide such details. As a result, there is no typical X interface and several desktop environments have been popular among users.

A window manager
X window manager

An X window manager is a window manager which runs on top of the X Window System, a windowing system mainly used on Unix-like systems.Unlike the Mac OS and Microsoft Windows platforms, which have historically provided a vendor-controlled, fixed set of ways to control how windows and paned windows display on a Computer display, and how the...
 controls the placement and appearance of application windows. This may result in interfaces akin to those of Microsoft Windows
Microsoft Windows

Microsoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces ....
 or the Macintosh (examples include Metacity
Metacity

Metacity is a compositing window manager used by default in the GNOME desktop environment. The development of Metacity was started by Havoc Pennington and it is released under the GNU General Public License....
 in GNOME
Gnome

A gnome is a mythical creature characterized by its extremely small size and wiktionary:subterranean lifestyle. The word gnome is derived from the New Latin gnomus....
, KWin
KWin

In Unix computing, KWin is a X window manager for the X Window System. It is an integral part of the KDE , although it can be used on its own or with other desktop environments....
 in KDE
KDE

KDE is a free software project based around its flagship product, a desktop environment for Unix-like systems. The goal of the project is to provide basic desktop functions and applications for daily needs as well as tools and documentation for developers to write stand-alone applications for the system....
 or Xfwm in Xfce
Xfce

Xfce is a free software desktop environment for Unix and other Unix-like platforms, such as Linux, Solaris and BSD. It aims to be fast and lightweight, while still being visually appealing and easy to use....
) or have radically different controls (such as a tiling window manager
Tiling window manager

In computing, a tiling window manager is a window manager with an organization of the screen into mutually non-overlapping frames, as opposed to the more popular approach of coordinate-based stacking of overlapping objects that tries to fully emulate the desktop metaphor....
, like wmii
Wmii

wmii is a dynamic tiling window manager window manager for X11. It supports classic and dynamic window management with extended Computer keyboard, computer mouse, and filesystem based remote control....
 or Ratpoison
Ratpoison

In Unix computing, ratpoison is a Free software window manager for the X Window System primarily written by Shawn Betts. Its user interface and much of its functionality are inspired by the GNU Screen computer terminal multiplexer....
). Window managers range in sophistication and complexity from the bare-bones (e.g., twm
Twm

In computing, twm is the standard X window manager for the X Window System, version X11R4 onwards. It is a re-parenting window manager that provides title bars, shaped windows and icon management, and is extensively configurable....
, the basic window manager supplied with X, or evilwm
Evilwm

evilwm is a window manager for the X Window System. It lacks traditional window manager decorations in that there is only a one pixel border around windows, and even this feature can be removed or re-adjusted from a command-line option....
, an extremely light window manager) to the more comprehensive desktop environments such as Enlightenment.

Many users use X with a desktop environment
Desktop environment

In graphical computing, a desktop environment commonly refers to a style of graphical user interface that is based on the desktop metaphor which can be seen on most modern personal computers today....
, which, aside from the window manager, include various applications using a consistent user interface. GNOME
Gnome

A gnome is a mythical creature characterized by its extremely small size and wiktionary:subterranean lifestyle. The word gnome is derived from the New Latin gnomus....
, KDE
KDE

KDE is a free software project based around its flagship product, a desktop environment for Unix-like systems. The goal of the project is to provide basic desktop functions and applications for daily needs as well as tools and documentation for developers to write stand-alone applications for the system....
 and Xfce
Xfce

Xfce is a free software desktop environment for Unix and other Unix-like platforms, such as Linux, Solaris and BSD. It aims to be fast and lightweight, while still being visually appealing and easy to use....
 are the most popular desktop environments. The Unix standard
Single UNIX Specification

The Single UNIX Specification is the collective name of a family of standards for computer operating systems to qualify for the name "Unix". The SUS is developed and maintained by the Austin Group, based on earlier work by the IEEE and The Open Group....
 environment is the Common Desktop Environment
Common Desktop Environment

The Common Desktop Environment is a desktop environment for Unix, based on the Motif widget toolkit. Hewlett-Packard OpenVMS uses CDE as its standard desktop environment....
 (CDE). The freedesktop.org
Freedesktop.org

freedesktop.org is a project to work on interoperability and shared base technology for free software desktop environments for the X Window System on Linux and other Unix-like operating systems....
 initiative addresses interoperability between desktops and the components needed for a competitive X desktop.

As X is responsible for keyboard and mouse interaction with graphical desktops, certain keyboard shortcut
Keyboard shortcut

In computing, a keyboard shortcut is a finite set of one or more Computer keyboards that invoke a software or operating system operation when triggered by the user....
s have become associated with X. Control-Alt-Backspace typically terminates the currently running X session, while Control-Alt in conjunction with a function key
Function key

A function key is a key on a computer or computer terminal computer keyboard which can be programmed so as to cause an operating system command interpreter or application program to perform certain actions....
 switches to the associated virtual console. However, this is an implementation detail left to the design of an X server implementation and is not universal; for example, X server implementations for Windows and Macintosh typically do not provide these keyboard shortcuts.

Implementations

The X.Org open source implementation serves as the canonical
Canonical

Canonical is an adjective derived from wikt:canon. Canon comes from the Greek word kanon, "rule" , and is used in various meanings....
 implementation of X. Due to liberal licensing, a number of variations, both free
Free software

Free Software or software libre is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with minimal restrictions only to ensure that further recipients can also do these things and to prevent consumer-facing hardware...
 and proprietary
Proprietary software

Proprietary software is a term coined by advocates of the free software movement to describe computer software which is the legal property of one party....
, have appeared. Commercial UNIX vendors have tended to take the open source implementation and adapt it for their hardware, usually customising it heavily and adding proprietary extensions. | |- |
Wfm Cygwinx Rootless
|}

Up to 2004, XFree86
XFree86

XFree86 is an implementation of the X Window System. It was originally written for Unix-like operating systems on IBM PC compatibles and is now available for many other operating systems and platforms....
 provided the most common X variant on free Unix-like
Unix-like

A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
 systems. XFree86 started as a port
Porting

In computer science, porting is the process of adapting software so that an executable Computer program can be created for a computing environment that is different from the one for which it was originally designed ....
 of X for 386
Intel 80386

The Intel 80386, otherwise known as the i386 or just 386, is a microprocessor which has been used as the central processing unit of many personal computers and workstations since 1986....
-compatible PCs and, by the end of the 1990s, had become the greatest source of technical innovation in X and the de facto standard of X development. Since 2004, however, the X.Org open source implementation
X.Org Server

The X.Org Server is the X server in the official reference implementation of the X Window System. The current stable release is 1.6.0, which is part of X11R7.5, and was released on 25 February 2009....
, a fork of XFree86, has become predominant.

While it is common to associate X with Unix, X servers also exist natively within other graphical environments. Hewlett-Packard
Hewlett-Packard

The Hewlett-Packard Company , commonly referred to as HP, is a technology corporation headquartered in Palo Alto, California, United States....
's OpenVMS
OpenVMS

OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is the name of a high-end computer server operating system that runs on the VAX and DEC Alpha families of computers, developed by Digital Equipment Corporation of Maynard, Massachusetts, Massachusetts , and most recently on Hewlett-Packard systems built around the In...
 operating system includes a version of X with CDE
Common Desktop Environment

The Common Desktop Environment is a desktop environment for Unix, based on the Motif widget toolkit. Hewlett-Packard OpenVMS uses CDE as its standard desktop environment....
, known as DECwindows, as its standard desktop environment. Apple
Apple Computer

Apple Inc., formerly Apple Computer Inc., is an United States multinational corporation which designs and manufactures consumer electronics and software products....
's Mac OS X v10.3
Mac OS X v10.3

Mac OS X version 10.3 ?Panther? was the fourth Software version of Mac OS X, Apple Inc. desktop and server operating system. It followed Mac OS X v10.2 ?Jaguar? and preceded Mac OS X v10.4 ?Tiger?....
 (Panther) and Mac OS X v10.4
Mac OS X v10.4

Mac OS X version 10.4 ?Tiger? was the fifth Software version of Mac OS X, Apple Inc. desktop and server operating system for Macintosh computers....
 (Tiger) includes X11.app
X11.app

X11.app is Apple Inc.'s implementation of the X Window System for Mac OS X. Apple's implementation of X11 is based on the X.Org Server and adds support for hardware-accelerated 2D computer graphics, hardware OpenGL acceleration and integration with Aqua , the Mac OS X graphical user interface ....
, based on XFree86 4.3 and X11R6.6, with better Mac OS X
Mac OS X

Mac OS X is a line of computer operating systems developed, marketed, and sold by Apple Inc., and since 2002 has been included with all new Macintosh computer systems....
 integration, on Mac OS X v10.5
Mac OS X v10.5

Mac OS X version 10.5 "Leopard" is the sixth Software version of Mac OS X, Apple Inc. desktop and server operating system for Apple Macintosh computers, and the successor to Mac OS X v10.4 "Tiger"....
 (Leopard) Apple included X.org (X11R7.2 Codebase) instead of XFree86 (X11R6.8). Third-party servers under Mac OS 7, 8 and 9 included White Pine Software's eXodus
Exodus

Exodus is the second book of the Jewish Torah and of the Christian Old Testament. It tells how Moses leads the Israelites out of Egypt and through the wilderness to the Mountain of God Sinai....
 and Apple
Apple Computer

Apple Inc., formerly Apple Computer Inc., is an United States multinational corporation which designs and manufactures consumer electronics and software products....
's MacX
MacX

MacX is an X11 server implementation that ran on System 7 , Mac OS 8, and Mac OS 9. It also ran under A/UX. Prior to X11R4 and the introduction of the PowerPC-based Power Macintosh, this server was developed internally for the Motorola 68000 by Apple Computer....
.

Microsoft Windows
Microsoft Windows

Microsoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces ....
 does not come with support for X, but many third-party implementations exist, both free software
Free software

Free Software or software libre is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with minimal restrictions only to ensure that further recipients can also do these things and to prevent consumer-facing hardware...
 such as Cygwin/X
Cygwin/X

Cygwin/X is an implementation of the X Window System that runs under Microsoft Windows. It is part of the Cygwin project, and is installed using Cygwin's standard setup system....
 and WeirdX
WeirdX

WeirdX is an X Window System server written in pure Java platform and licensed under GNU GNU General Public License by JCraft. It is derived from WiredX-lite, a commercial branch of the software, and provides limited support of the X11R6.3 protocol through JDK/JRE 1.1....
; and proprietary products such as Xmanager, Xming
Xming

Xming is an porting of the X Window System computer software to the Microsoft Windows operating system, including XP, 2003 and Vista. The Xming X Server is based on the X.Org Server, cross-compiled on Linux with the MinGW compiler suite and Pthreads-Win32....
, MKS X/Server
MKS X/Server

MKS X/Server is for a commercial X server product for accessing UNIX/Linux systems from a PC developed by MKS Inc.. The product offers both a full 32-bit X server and a native 64-bit X server that operates on various versions of the Microsoft Windows operating system....
, Exceed and X-Win32
X-Win32

In computing, X-Win32 is a proprietary software X Window System server for Microsoft Windows, produced by StarNet Communications. It is based on X11R6....
. They normally serve to control remote X clients.

When another windowing system (such as those of Microsoft Windows or Mac OS) hosts X, the X system generally runs "rootless", meaning the host windowing environment looks after the root window (the background and associated menus) and manages the geometry of the hosted X windows — although some servers can also create the root window for the remote clients to display to as a separate window in the host system.

X terminals

Network Computing Devices Ncd 88k X Terminal
An X terminal is a thin client
Thin client

A thin client is a client computer or client software in client-server architecture networks which depends primarily on the central Server for processing activities, and mainly focuses on conveying input and output between the user and the remote server....
 that runs an X server. This architecture became popular for building inexpensive terminal parks for many users to simultaneously use the same large server (making programs being run on the server clients of the X terminal). This use very much aligns with the original intention of the MIT project.

X terminals explore the network (the local broadcast domain
Broadcast domain

A broadcast domain is a logical division of a computer network, in which all node s can reach each other by broadcasting at the data link layer....
) using the X Display Manager Control Protocol to generate a list of available hosts that they can run clients from. The initial host needs to run an X display manager
X display manager

In the X Window System, an X display manager runs as a program, that allows the starting of a login session on an X Server from the same or another computer....
.

Dedicated (hardware) X terminals have become less common; a PC
Personal computer

A personal computer is any general-purpose computer whose original sales price, size, and capabilities make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator....
 or modern thin client
Thin client

A thin client is a client computer or client software in client-server architecture networks which depends primarily on the central Server for processing activities, and mainly focuses on conveying input and output between the user and the remote server....
 with an X server typically provides the same functionality at the same, or lower, cost.

Limitations and criticisms of X

The UNIX-HATERS Handbook
The UNIX-HATERS Handbook

The UNIX-HATERS Handbook is a semi-humorous edited compilation of messages to the UNIX-HATERS mailing list. The book was edited by Simson Garfinkel, Daniel Weise and Steven Strassmann and published in 1994....
 (1994) devoted an entire chapter to the problems of X. Why X Is Not Our Ideal Window System (1990) by Gajewska, Manasse and McCormack detailed problems in the protocol with recommendations for improvement.

User interface issues

The lack of design guidelines in X has resulted in several vastly different interfaces, and in applications that have not always worked well together. The ICCCM
Inter-Client Communication Conventions Manual

In computing, the Inter-Client Communication Conventions Manual is a standard for interoperability between X Window System client of the same X Window System protocols and architecture....
, a specification for client interoperability, has a reputation as being difficult to implement correctly. Further standards efforts such as Motif
Motif (widget toolkit)

In computing, Motif refers to both a graphical user interface specification and the widget toolkit for building applications that follow that specification under the X Window System on Unix and other POSIX-compliant systems....
 and CDE
Common Desktop Environment

The Common Desktop Environment is a desktop environment for Unix, based on the Motif widget toolkit. Hewlett-Packard OpenVMS uses CDE as its standard desktop environment....
 did not alleviate problems. This has frustrated users and programmers. Graphics programmers now generally address consistency of application look and feel
Look and feel

Look and feel is a term used in descriptions of products and fields such as product design, marketing, branding and trademarking, to describe the main features of its appearance....
 and communication by coding to a specific desktop environment or to a specific widget toolkit, which also avoids having to deal directly with the ICCCM.

The X protocol provides no facilities for handling audio, leaving it to the operating system or its audio subsystems like OSS
Open Sound System

The Open Sound System is a standard interface for making and capturing sound in Unix operating systems. It is based on standard Unix devices ....
 or ALSA to provide support for audio hardware and sound playback. Most programmers simply use local, OS-specific sound API
Application programming interface

An application programming interface is a set of subroutine, data structures, class and/or Protocol provided by library and/or operating system Service s in order to support the building of applications....
s. The first generation of client-server sound systems included rplay and Network Audio System
Network Audio System

The Network Audio System is an open-source software, network transparency, client-server audio transport system. It can be described as the audio equivalent of the X Window System....
. More recent efforts have produced EsounD
Enlightened Sound Daemon

In computing, the Enlightened Sound Daemon is the sound server for Enlightenment and GNOME.ESD will mix together the simultaneous audio output of multiple running programs, and output the resulting stream to the sound card....
 (GNOME), aRts
ARts

aRts, which stands for analog Real time synthesizer, is an audio framework that is no longer under development. It is most famous for previously being used in KDE to simulate an analog synthesizer....
 (KDE), and PulseAudio
PulseAudio

PulseAudio is a cross-platform, networked sound server project. It is intended to be an improved drop-in replacement for the Enlightened Sound Daemon ....
 to name a few. In 2001, the X.org
X.Org

X.Org refers to:* The X.Org Foundation, stewards of the X Window System.* The X.Org Server, the reference implementation of X developed by the Foundation....
 foundation announced the development of the Media Application Server (MAS) to remedy this problem. However, none of these are generally used as a solution to the problem. Another effort, , was announced by Helge Bahmann in September 2007 as an extension to the X server.

Network

X11 Ssh Tunnelling
An X client cannot generally be detached from one server and reattached to another, as with Virtual Network Computing
Virtual Network Computing

In computing, Virtual Network Computing is a graphical desktop sharing system that uses the RFB protocol to remotely control another computer....
 (VNC), though certain specific applications and toolkits are able to provide this facility. Workarounds (VNC :0 viewers) also exist to make the current X-server screen available via VNC.

Network traffic between an X server and remote X clients is not encrypted by default. An attacker with a packet sniffer
Packet sniffer

A packet analyzer is computer software or computer hardware that can intercept and log traffic passing over a digital telecommunications network or part of a network....
 can intercept it, making it possible to view anything displayed to or sent from the user's screen. The most common way to encrypt X traffic is to establish a Secure Shell
Secure Shell

Secure Shell or SSH is a network protocol that allows data to be exchanged using a secure channel between two networked devices. Used primarily on Linux and Unix based systems to access shell accounts, SSH was designed as a replacement for TELNET and other Computer security remote Shell s, which send information, notably passwords, in...
 (SSH) tunnel for communication.

Client-server separation

X's design requires the clients and server to operate separately, and device independence and the separation of client and server incur overhead. Most of the overhead comes from network round-trip delay time
Round-trip delay time

In telecommunications, the term round-trip delay time or round-trip time has the following meanings:# The elapsed time for transit of a signal processing over a closed circuit, or time elapsed for a message to a remote place and back again....
 between client and server (latency
Latency (engineering)

Latency is a time delay between the moment something is initiated, and the moment one of its effects begins or becomes detectable. The word derives from the fact that during the period of latency the effects of an action are latent, meaning "potential" or "not yet observed"....
 rather than from the protocol itself): the best solutions to performance issues depend on efficient application design. A common criticism of X is that its network features result in excessive complexity and decreased performance if only used locally. That used to be the case, but modern X implementations are able to use unix domain sockets and shared memory
Shared memory

In computing, shared memory is a memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies....
 (the MIT-SHM
MIT-SHM

The MIT Shared Memory Extension or MIT-SHM is a X Window System extension for exchange of image data between client and server using shared memory....
 extension) to work around the network overhead. The programmer must still explicitly activate and use those extensions in order to improve performance and must also provide fallback paths in order to stay compatible with older implementations.

Competitors to X

For graphics, Unix-like
Unix-like

A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
 systems use X almost universally. However, some people have attempted writing alternatives to and replacements for X. Historical alternatives include Sun
Sun Microsystems

Sun Microsystems, Inc. is a multinational corporation vendor of computers, computer components, computer software, and information technology services, founded on February 24, 1982....
's NeWS
NeWS

NeWS was a windowing system developed by Sun Microsystems in the mid 1980s. Originally known as "SunDew", its primary authors were James Gosling and David S....
, which failed in the market, and NeXT
NeXT

NeXT, Inc. was an American computer company headquartered in Redwood City, California, California, that developed and manufactured a series of computer workstations intended for the higher education and business markets....
's Display PostScript
Display PostScript

Display PostScript is an on-screen display system. As the name implies, DPS uses the PostScript imaging model and language to generate on-screen graphics....
, which was discarded in favor of Apple
Apple Computer

Apple Inc., formerly Apple Computer Inc., is an United States multinational corporation which designs and manufactures consumer electronics and software products....
's entirely new Quartz
Quartz (graphics layer)

Quartz specifically refers to a pair of Mac OS X technologies, each part of the Core Graphics framework: Quartz 2D and Quartz Compositor. It includes both a 2D renderer in Core Graphics and the composition engine that sends instructions to the graphics card....
 in Mac OS X
Mac OS X

Mac OS X is a line of computer operating systems developed, marketed, and sold by Apple Inc., and since 2002 has been included with all new Macintosh computer systems....
.

Mike Paquette, one of the authors of Quartz, explained why Apple did not move from Display PostScript to X, and chose instead to develop its own window server, by saying that once Apple added support for all the features it wanted to include in to X11, it would not bear much resemblance to X11 nor be compatible with other servers anyway.

Other attempts to address criticisms of X by replacing it completely include Berlin/Fresco
Fresco (computing)

In computing, Fresco is a windowing system. It was intended as a replacement for the X Window System. As of October 23, 2008, the last activity in was dated June 11, 2004....
 and the Y Window System
Y Window System

The Y Window System is a windowing system, consisting of a window Server and a client Library for writing applications. It was written by Mark Thomas as the subject of his Master's thesis at Imperial College, London....
. These alternatives have seen negligible take-up, however, and commentators widely doubt the viability of any replacement that does not preserve backward compatibility with X.

Other competitors attempt to avoid the overhead of X by working directly with the hardware. Such projects include DirectFB
DirectFB

DirectFB stands for Direct Frame Buffer. It is a library for the GNU/Linux operating system that provides "hardware graphics acceleration, input device handling and abstraction, integrated windowing system with support for translucent windows and multiple display layers on top of the Linux framebuffer Device." ...
 and the very small FBUI. The Direct Rendering Infrastructure
Direct Rendering Infrastructure

In computing, the Direct Rendering Infrastructure is an interface and a free software implementation used in the X Window System to securely allow user applications to access the video hardware without requiring data to be passed through the X server....
 (DRI), which aims to provide a reliable kernel-level interface to the framebuffer
Framebuffer

A framebuffer is a video output device that drives a video display from a memory buffer containing a complete video frame of data. The information in the buffer typically consists of color values for every pixel on the screen....
, may make these efforts redundant. However, in Linux
Linux

Linux is a generic term referring to Unix-like computer operating systems based on the Linux kernel. Their development is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed by anyone under the terms of the GNU GPL license...
 embedded systems requiring real-time capabilities (e.g. using RTAI
RTAI

RTAI stands for real-time computing Application Interface. It is a real-time extension for the Linux kernel - which lets you write applications with strict timing constraints for Linux....
), the use of hardware acceleration via DRI is discouraged; X may be unsuitable for such applications.

Other ways to achieve network transparency for graphical services include:
  • the , a protocol to update Scalable Vector Graphics
    Scalable Vector Graphics

    Scalable Vector Graphics is a family of specifications of XML-based file format for describing two-dimensional vector graphics, both static and dynamic ....
     (SVG) content in a browser in near-real-time
  • Virtual Network Computing
    Virtual Network Computing

    In computing, Virtual Network Computing is a graphical desktop sharing system that uses the RFB protocol to remotely control another computer....
     (VNC), a very low-level system which sends compressed bitmaps across the network; the Unix implementation includes an X server
  • Citrix XenApp, an X-like product for Microsoft Windows
  • Tarantella
    Tarantella, Inc.

    Santa Cruz Operation was a software company based in Santa Cruz, California which was best known for selling three Unix variants for Intel x86 processors: Xenix, SCO UNIX , and UnixWare....
    , which provides a Java client for use in web browsers
  • RAWT, IBM's Java-only , which implements a Java "server" and simple hooks for any remote Java client (see also: )


History


Predecessors

Several bitmap display systems preceded X. From Xerox
Xerox

Xerox Corporation is a global document management company which manufactures and sells a range of color and black-and-white Computer printer, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies....
 came the Alto
Xerox Alto

The Xerox Alto was an early personal computer developed at Xerox PARC in 1973. It was the first computer to use the desktop metaphor and graphical user interface ....
 (1973) and the Star
Xerox Star

The Star workstation, officially known as the Xerox 8010 Information System, was introduced by Xerox Corporation in 1981. It was the first commercial system to incorporate various technologies that today have become commonplace in personal computers, including a raster graphics display, a window-based graphical user interface, icon , f...
 (1981). From Apple
Apple Computer

Apple Inc., formerly Apple Computer Inc., is an United States multinational corporation which designs and manufactures consumer electronics and software products....
 came the Lisa
Apple Lisa

The Apple Lisa was a personal computer designed at Apple Computer, Inc. during the early 1980s.The Lisa project was started at Apple in 1978 and evolved into a project to design a powerful personal computer with a graphical user interface that would be targeted toward business customers....
 (1983) and the Macintosh (1984). The Unix
Unix

Unix is a computer operating system originally developed in 1969 by a group of American Telephone & Telegraph employees at Bell Labs, including Ken Thompson , Dennis Ritchie, Douglas McIlroy, and Joe Ossanna....
 world had the Andrew Project
Andrew Project

The Andrew Project was a distributed computing environment begun in 1983, driven by the Information Technology Center, a jointCarnegie Mellon University and IBM project....
 (1982) and Rob Pike
Rob Pike

Robert C. Pike is a software engineer and author. He is best known for his work at Bell Labs, where he was a member of the Unix team and was involved in the creation of the Plan 9 from Bell Labs and Inferno operating systems, as well as the Limbo programming language....
's Blit
Blit (computer terminal)

In computing, the Blit is a programmable bitmap computer graphics computer terminal designed by Rob Pike and Bart Locanthi of Bell Labs in 1982....
 terminal (1982).

X derives its name as a successor to a pre-1983 window system called W
W Window System

The W Window System is a graphical windowing system and precursor in name and concept to the modern X Window System.W was originally developed at Stanford University by Paul Asente and Brian Reid for the V operating system....
 (the letter preceding X in the English alphabet
English alphabet

The modern English alphabet is a Latin-based alphabet consisting of 26 letters, like in the Basic modern Latin alphabet:The exact shape of printed letters varies depending on the typeface....
). W Window System ran under the V operating system
V (operating system)

The V operating system is a Kernel operating system that was developed by faculty and students in the Distributed Systems Group at Stanford University in the 1980s, led primarily by Prof....
. W used a network protocol supporting terminal and graphics windows, the server maintaining display lists.

Origin and early development

The original idea of X emerged at MIT in 1984 as a collaboration between Jim Gettys
Jim Gettys

Jim Gettys is a computer programmer. Until January 2009, he was the Vice President of Software at the One Laptop per Child project, working on the software for the OLPC XO-1....
 (of Project Athena
Project Athena

Project Athena was a joint project of Massachusetts Institute of Technology, Digital Equipment Corporation, and IBM to produce a campus-wide distributed computing environment for educational use....
) and Bob Scheifler
Bob Scheifler

Robert William Scheifler is a computer scientist. He is most notable for leading the development of the X Window System from the project's inception in 1984 until the closure of the MIT X Consortium in 1996....
 (of the MIT Laboratory for Computer Science). Scheifler needed a usable display environment for debugging the Argus system. Project Athena
Project Athena

Project Athena was a joint project of Massachusetts Institute of Technology, Digital Equipment Corporation, and IBM to produce a campus-wide distributed computing environment for educational use....
 (a joint project between Digital Equipment Corporation
Digital Equipment Corporation

Digital Equipment Corporation was a pioneering United States company in the computer industry. It is often referred to within the computing industry as DEC ....
 (DEC), MIT and IBM
IBM

International Business Machines Corporation, abbreviated IBM and nicknamed "Big Blue" , is a multinational corporation computer technology and consulting corporation headquartered in Armonk, New York, New York, United States....
 to provide easy access to computing resources for all students) needed a platform-independent graphics system to link together its heterogeneous multiple-vendor systems; the window system then under development in Carnegie Mellon University
Carnegie Mellon University

Carnegie Mellon University is a top private university research university in Pittsburgh. Since its inception, Carnegie Mellon has grown into a world-renowned institution, with numerous programs that are frequently college and university rankings among the best in the world....
's Andrew Project
Andrew Project

The Andrew Project was a distributed computing environment begun in 1983, driven by the Information Technology Center, a jointCarnegie Mellon University and IBM project....
 did not make licenses available, and no alternatives existed.

The project solved this by creating a protocol that could both run local applications and call on remote resources. In mid-1983 an initial port of W to Unix ran at one-fifth of its speed under V; in May 1984, Scheifler replaced the synchronous protocol
Protocol (computing)

In computer science, a protocol is a convention or standard that controls or enables the connection, communication, and data transfer between computing endpoints....
 of W with an asynchronous protocol and the display lists with immediate mode graphics to make X version 1. X became the first windowing system environment to offer true hardware-independence and vendor-independence.

Scheifler, Gettys and Ron Newman
Ron Newman (computer programmer)

Ron Newman is a computer programmer. He is most famous for his work in the early development of the X Window System, from the first version in 1984 to X11R2 in 1988....
 set to work and X progressed rapidly. They released Version 6 in January 1985. DEC, then preparing to release its first Ultrix
Ultrix

Ultrix was the brand name of Digital Equipment Corporation's native Unix systems. While ultrix is the Latin word for avenger, the name was chosen solely for its sound....
 workstation, judged X the only windowing system likely to become available in time. DEC engineers ported X6 to DEC's QVSS display on MicroVAX
MicroVAX

The MicroVAX is a family of low-end minicomputers developed and manufactured by Digital Equipment Corporation . The first model, the MicroVAX I, was introduced in 1984....
.

In the second quarter of 1985 X acquired color
X11 color names

In computing, on the X Window System, X11 color names are represented in a simple text file, which maps certain strings to RGB color values. It is shipped with every "X" installation, hence the name, and is usually located in <X11root>/lib/X11/rgb.txt....
 support to function in the DEC VAXstation
VAXstation

The VAXstation is a family of workstation computers developed and manufactured by Digital Equipment Corporation using processors implementing the VAX instruction set architecture ....
-II/GPX, forming what became version 9.

A group at Brown University
Brown University

Brown University is a private university university located in , United States and is a member of the Ivy League. Founded in 1764 as the College of Rhode Island, it is the third-oldest institution of higher education in New England and Colonial Colleges in the United States....
 ported version 9 to the IBM
IBM

International Business Machines Corporation, abbreviated IBM and nicknamed "Big Blue" , is a multinational corporation computer technology and consulting corporation headquartered in Armonk, New York, New York, United States....
 RT/PC, but problems with reading unaligned data on the RT forced an incompatible protocol change, leading to version 10 in late 1985. By 1986, outside organizations had started asking for X. The release of X10R2 took place in January 1986; that of X10R3 in February 1986. Although MIT had licensed X6 to some outside groups for a fee, it decided at this time to license X10R3 and future versions under what became known as the MIT License
MIT License

The MIT License is a free software license originating at the Massachusetts Institute of Technology , used by the MIT X Consortium.It is a Permissive_free_software_licence license, meaning that it permits reuse within proprietary software on the condition that the license is distributed with that software....
, intending to popularize X further and in return, hoping that many more applications would become available. X10R3 became the first version to achieve wide deployment, with both DEC and Hewlett-Packard
Hewlett-Packard

The Hewlett-Packard Company , commonly referred to as HP, is a technology corporation headquartered in Palo Alto, California, United States....
 releasing products based on it. Other groups ported X10 to Apollo
Apollo Computer

Apollo Computer, Inc., founded 1980 in Chelmsford, Massachusetts by William Poduska , developed and produced Apollo/Domain workstations in the 1980s....
 and to Sun
Sun Microsystems

Sun Microsystems, Inc. is a multinational corporation vendor of computers, computer components, computer software, and information technology services, founded on February 24, 1982....
 workstations and even to the IBM PC/AT. Demonstrations of the first commercial application for X (a mechanical computer-aided engineering system from Cognition Inc. that ran on VAXes and displayed on PCs running an X server) took place at the Autofact trade show at that time. The last version of X10, X10R4, appeared in December 1986.

Attempts were made to enable X servers as real-time collaboration devices, much as Virtual Network Computing
Virtual Network Computing

In computing, Virtual Network Computing is a graphical desktop sharing system that uses the RFB protocol to remotely control another computer....
 (VNC) would later allow a desktop to be shared. One such early effort was Philip J. Gust's SharedX
SharedX

SharedX was a tool developed at HP in the mid 1980s to allow X servers to "shared" a window, thus allowing users at multiple workstations to interact with the same X window....
 tool.

Although X10 offered interesting and powerful functionality, it had become obvious that the X protocol could use a more hardware-neutral redesign before it became too widely deployed; but MIT alone would not have the resources available for such a complete redesign. As it happened, DEC's Western Software Laboratory found itself between projects with an experienced team. Smokey Wallace of DEC WSL and Jim Gettys proposed that DEC WSL build X11 and make it freely available under the same terms as X9 and X10. This process started in May 1986, with the protocol finalized in August. Alpha-testing of the software started in February 1987, beta-testing in May; the release of X11 finally occurred on September 15, 1987.

The X11 protocol design, led by Scheifler, was extensively discussed on open mailing lists on the nascent Internet
Internet

The Internet is a global network of interconnected computers, enabling users to share information along multiple channels. Typically, a computer that connects to the Internet can access information from a vast array of available server and other computers by moving information from them to the computer's local memory....
 that were bridged to USENET newsgroups. Gettys moved to California to help lead the X11 development work at WSL from DEC's Systems Research Center, where Phil Karlton and Susan Angebrandt led the X11 sample server design and implementation. X therefore represents one of the first very large-scale distributed free software
Free software

Free Software or software libre is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with minimal restrictions only to ensure that further recipients can also do these things and to prevent consumer-facing hardware...
 projects.

The MIT X Consortium and the X Consortium, Inc.

In 1987, with the success of X11 becoming apparent, MIT wished to relinquish the stewardship of X, but at a June 1987 meeting with nine vendors, the vendors told MIT that they believed in the need for a neutral party to keep X from fragmenting in the marketplace. In January 1988, the MIT X Consortium formed as a non-profit vendor group, with Scheifler as director, to direct the future development of X in a neutral atmosphere inclusive of commercial and educational interests. Jim Fulton joined in January 1988 and Keith Packard
Keith Packard

Keith Packard is a software developer, best known for his work on the X Window System.Packard is responsible for many X extensions and technical papers on X....
 in March 1988 as senior developers, with Jim focusing on Xlib
Xlib

Xlib is an X Window System protocol client library in the C . It contains subroutines for interacting with an X Server . These functions allow programmers to write programs without knowing the details of the protocol ....
, fonts
Computer font

A computer font is an electronic data file containing a set of glyphs, characters, or symbols such as dingbats. Although the term font first referred to a set of metal type sorts in one style and size, since the 1990s most fonts are digital, used on computers....
, window managers, and utilities; and Keith re-implementing the server. Donna Converse and Chris D. Peterson joined later that year, focusing on toolkits and widget sets, working closely with Ralph Swick of MIT Project Athena. The MIT X Consortium produced several significant revisions to X11, the first (Release 2 - X11R2) in February 1988.
Decwindows Openvms V7
In 1993, the X Consortium, Inc. (a non-profit corporation) formed as the successor to the MIT X Consortium. It released X11R6 on May 16, 1994. In 1995 it took on the development of the Motif
Motif (widget toolkit)

In computing, Motif refers to both a graphical user interface specification and the widget toolkit for building applications that follow that specification under the X Window System on Unix and other POSIX-compliant systems....
 toolkit and of the Common Desktop Environment
Common Desktop Environment

The Common Desktop Environment is a desktop environment for Unix, based on the Motif widget toolkit. Hewlett-Packard OpenVMS uses CDE as its standard desktop environment....
 for Unix systems. The X Consortium dissolved at the end of 1996, producing a final revision, X11R6.3, and a legacy of increasing commercial influence in the development.

The Open Group

In January 1997 the X Consortium passed stewardship of X to The Open Group
The Open Group

The Open Group is an industry consortium to set vendor- and technology-neutral open standards for computing infrastructure. It was formed when X/Open merged with the Open Software Foundation in 1996....
, a vendor group formed in early 1996 by the merger of the Open Software Foundation
Open Software Foundation

The Open Software Foundation was an organization founded in 1988 to create an open standard for an implementation of the Unix operating system....
 and X/Open
X/Open

X/Open Company, Ltd. was a consortium founded by several European UNIX systems manufacturers in 1984 to identify and promote open standards in the field of information technology....
.

The Open Group released X11R6.4 in early 1998. Controversially, X11R6.4 departed from the traditional liberal licensing terms, as the Open Group sought to assure funding for the development of X. The new terms would have prevented its adoption by many projects (such as XFree86
XFree86

XFree86 is an implementation of the X Window System. It was originally written for Unix-like operating systems on IBM PC compatibles and is now available for many other operating systems and platforms....
) and even by some commercial vendors. After XFree86 seemed poised to fork, the Open Group relicensed X11R6.4 under the traditional license in September 1998. The Open Group's last release came as X11R6.4 patch 3.

X.Org and XFree86

XFree86
XFree86

XFree86 is an implementation of the X Window System. It was originally written for Unix-like operating systems on IBM PC compatibles and is now available for many other operating systems and platforms....
 originated in 1992 from the X386
X386

X386 was the first implementation of the X Window System for IBM PC compatible computers. It ran on systems with Intel 386 or later processors, running Unix System V-based operating systems, and supported a variety of VGA-compatible graphics cards....
 server for IBM PC compatible
IBM PC compatible

IBM PC compatible computers are those generally similar to the original IBM Personal Computer, IBM Personal Computer XT, and IBM Personal Computer/AT....
s included with X11R5 in 1991, written by Thomas Roell and Mark W. Snitily and donated to the MIT X Consortium by Snitily Graphics Consulting Services (SGCS). XFree86 evolved over time from just one port of X to the leading and most popular implementation and the de facto steward of X's development.

In May 1999, the Open Group formed X.Org
X.Org

X.Org refers to:* The X.Org Foundation, stewards of the X Window System.* The X.Org Server, the reference implementation of X developed by the Foundation....
. X.Org supervised the release of versions X11R6.5.1 onward. X development at this time had become moribund; most technical innovation since the X Consortium had dissolved had taken place in the XFree86 project. In 1999, the XFree86 team joined X.Org as an honorary (non-paying) member, encouraged by various hardware companies interested in using XFree86 with Linux and in its status as the most popular version of X.

By 2003, while the popularity of Linux (and hence the installed base of X) surged, X.Org remained inactive, and active development took place largely within XFree86. However, considerable dissent developed within XFree86. The XFree86 project suffered from a perception of a far too cathedral
The Cathedral and the Bazaar

The Cathedral and the Bazaar is an essay by Eric S. Raymond on software engineering methods, based on his observations of the Linux kernel development process and his experiences managing an open source project, fetchmail....
-like development model; developers could not get CVS
Concurrent Versions System

In the field of software development, the Concurrent Versions System , also known as the Concurrent Versioning System, is a free software revision control system....
 commit access and vendors had to maintain extensive patch sets
Patch (computing)

A patch is a small piece of software designed to fix problems with or update a computer program or its supporting data. This includes fixing computer bug, replacing graphics and improving the usability or performance....
. In March 2003 the XFree86 organization expelled Keith Packard, who had joined XFree86 after the end of the original MIT X Consortium, with considerable ill-feeling.

X.Org and XFree86 began discussing a reorganisation suited to properly nurturing the development of X. Jim Gettys had been pushing strongly for an open development model since at least 2000. Gettys, Packard and several others began discussing in detail the requirements for the effective governance of X with open development.

Finally, in an echo of the X11R6.4 licensing dispute, XFree86 released version 4.4 in February 2004 under a more restricted license which many projects relying on X found unacceptable. The added clause to the license was based upon the original BSD license's advertising clause, which was viewed by the Free Software Foundation
Free Software Foundation

The Free Software Foundation is a non-profit corporation founded by Richard Stallman on 4 October 1985 to support the free software movement, a copyleft-based movement which aims to promote the universal freedom to distribute and modify computer software without restriction....
 and Debian
Debian

Debian GNU/Linux is one of the most popular and influential computer operating systems composed of free software and open source software....
 as incompatible with the GNU General Public License
GNU General Public License

The GNU General Public License is a widely used free software license, originally written by Richard Stallman for the GNU project. The GPL is the most popular and well-known example of the type of strong copyleft license that requires derived works to be available under the same copyleft....
. Other groups saw further restrictions as being against the spirit of the original X (OpenBSD
OpenBSD

OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley....
 threatening a fork, for example). The license issue, combined with the difficulties in getting changes in, left many feeling the time was ripe for a fork.

The X.Org Foundation

In early 2004 various people from X.Org and freedesktop.org formed the X.Org Foundation
X.Org Foundation

The X.Org Foundation is the organization holding the stewardship for the development of the X Window System. It was founded on 22 January 2004....
, and the Open Group gave it control of the x.org domain name
Domain name

The term domain name has multiple related meanings:* A hostname that identifies a computer or computers on the Internet. These names appear as a component of a Web site's Uniform Resource Locator, e.g....
. This marked a radical change in the governance of X. Whereas the stewards of X since 1988 (including the previous X.Org) had been vendor organizations, the Foundation was led by software developers and used community development based on the bazaar
The Cathedral and the Bazaar

The Cathedral and the Bazaar is an essay by Eric S. Raymond on software engineering methods, based on his observations of the Linux kernel development process and his experiences managing an open source project, fetchmail....
 model, which relies on outside involvement. Membership was opened to individuals, with corporate membership being in the form of sponsorship. Several major corporations such as Hewlett-Packard
Hewlett-Packard

The Hewlett-Packard Company , commonly referred to as HP, is a technology corporation headquartered in Palo Alto, California, United States....
 and Sun Microsystems
Sun Microsystems

Sun Microsystems, Inc. is a multinational corporation vendor of computers, computer components, computer software, and information technology services, founded on February 24, 1982....
 currently support the X.Org Foundation.

The Foundation takes an oversight role over X development: technical decisions are made on their merits by achieving rough consensus among community members. Technical decisions are not made by the board of directors; in this sense, it is strongly modelled on the technically non-interventionist GNOME Foundation
GNOME Foundation

The GNOME Foundation is a non-profit organization based in Cambridge, Massachusetts, United States, coordinating the efforts in the GNOME project....
. The Foundation does not employ any developers.

The Foundation released X11R6.7, the X.Org Server
X.Org Server

The X.Org Server is the X server in the official reference implementation of the X Window System. The current stable release is 1.6.0, which is part of X11R7.5, and was released on 25 February 2009....
, in April 2004, based on XFree86 4.4RC2 with X11R6.6 changes merged. Gettys and Packard had taken the last version of XFree86 under the old license and, by making a point of an open development model and retaining GPL compatibility, brought many of the old XFree86 developers on board.

X11R6.8 came out in September 2004. It added significant new features, including preliminary support for translucent windows and other sophisticated visual effects, screen magnifiers and thumbnailers, and facilities to integrate with 3D immersive display systems such as Sun's Project Looking Glass
Project Looking Glass

Project Looking Glass is a free software project under the GNU General Public License to create an innovative 3D computer graphics desktop environment for Linux, Solaris Operating System, and Microsoft Windows....
 and the Croquet project
Croquet Project

The Croquet Project is an international effort to promote the continued development of Croquet, a free software Computer software Platform and a Computer network operating system for developing and delivering deeply collaborative multi-user online Application software....
. External applications called compositing window manager
Compositing window manager

A compositing window manager is a component of a computer's graphical user interface that draws windows and/or their borders. It also controls how they are displayed and interact with each other, and the rest of the desktop environment....
s
provide policy for the visual appearance.

On December 21, 2005 , X.Org released X11R6.9, the monolithic source
Source code

In computer science, source code is any collection of statements or declarations written in some human-readable computer programming language....
 tree for legacy users, and X11R7.0, the same source code separated into independent modules, each maintainable in separate projects. The Foundation released X11R7.1 on May 22, 2006, about four months after 7.0, with considerable feature improvements.

Future directions

With the X.Org Foundation and freedesktop.org, the main line of X development has started to progress rapidly once more. The developers intend to release present and future versions as usable finished products, not merely as bases for vendors to build a product upon.

For sufficiently capable combinations of hardware and operating systems, X.Org plans to access the video hardware only via the Direct Rendering Infrastructure
Direct Rendering Infrastructure

In computing, the Direct Rendering Infrastructure is an interface and a free software implementation used in the X Window System to securely allow user applications to access the video hardware without requiring data to be passed through the X server....
 (DRI), using the 3D hardware. The DRI first appeared in XFree86 version 4.0 and became standard in X11R6.7 and later. Many operating systems have started to add kernel support for hardware manipulation. This work proceeds incrementally.

Another new project, called Wayland and still at the embryonal status, is being developed by Kristian Høgsberg at Freedesktop.org
Freedesktop.org

freedesktop.org is a project to work on interoperability and shared base technology for free software desktop environments for the X Window System on Linux and other Unix-like operating systems....
. The project's aim is to create a nano display server, relying on DRM
Direct Rendering Manager

The Direct Rendering Manager is a component of the Direct Rendering Infrastructure, a system to provide efficient video acceleration on Unix-like operating systems, e.g....
 modesetting, GEM
Graphics Execution Manager

The GEM is a modern memory manager specialized for use in device drivers for Graphics processing unit. It manages graphics memory, controls the Execution_#Context_of_execution and manages the Non-Uniform Memory Access environment on modern graphics chipsets....
 batchbuffer submission and hardware initialization done in the kernel.

Nomenclature

People in the computer trade commonly shorten the phrase "X Window System" to "X Window", "X11" (for version 11, used since 1987) or simply to "X". The term "X-Windows" (in the manner of "Microsoft Windows") is not officially endorsed, though it has been in common use since early in the history of X and has been used deliberately for literary effect, for example in the UNIX-HATERS Handbook.

Release history


VersionRelease dateMost important changes
X1June 1984First use of the name "X"; fundamental changes distinguishing the product from W
W Window System

The W Window System is a graphical windowing system and precursor in name and concept to the modern X Window System.W was originally developed at Stanford University by Paul Asente and Brian Reid for the V operating system....
.
X6January 1985First version licensed to a handful of outside companies.
X9September 1985Color. First release under MIT License
MIT License

The MIT License is a free software license originating at the Massachusetts Institute of Technology , used by the MIT X Consortium.It is a Permissive_free_software_licence license, meaning that it permits reuse within proprietary software on the condition that the license is distributed with that software....
.
X10late 1985IBM RT/PC, AT (running DOS), and others
X10R2January 1986 
X10R3February 1986First freely redistributable X release. Earlier releases required a BSD source license to cover code changes to init/getty to support login. uwm made standard window manager.
X10R4December 1986Last version of X10.
X11September 15, 1987First release of the current protocol.
X11R2February 1988First X Consortium release.
X11R3October 25, 1988XDM
XDM

XDM is the default X display manager for the X Window System. It is a bare-bones X display manager. It was introduced with X11 Release 3 in October 1988, to support the standalone X terminals that were just coming onto the market....
X11R4December 22, 1989XDMCP, twm
Twm

In computing, twm is the standard X window manager for the X Window System, version X11R4 onwards. It is a re-parenting window manager that provides title bars, shaped windows and icon management, and is extensively configurable....
 brought in as standard window manager, application improvements, Shape extension
Shape extension

In the X Window System, the shape extension allows window s to be given arbitrary, non-rectangular shapes.Two well-known applets that use the shape extension are oclock, which is a simple round analog clock, and xeyes, which shows two googly eyes that follow the cursor on the screen as if they were watching it....
, new fonts.
X11R4/X11R5December 1989Commodore
Commodore International

Commodore, the commonly used name for Commodore International, was a United States electronics company based in West Chester, Pennsylvania which was a vital player in the home computer/personal computer field in the 1980s....
 sells the Amiga 2500
Amiga 2500

The Amiga 2500, also known as the A2500, was not a distinct Amiga model, but simply a marketing name for a Commodore International Amiga 2000 bundled with a Motorola 68020 or Motorola 68030-based accelerator card....
/UX (Unix based). It was the first computer sold on the market featuring standard X11 based desktop GUI called Open Look
OPEN LOOK

OPEN LOOK is a graphical user interface specification for UNIX computer workstations. It was originally defined in the late 1980s by Sun Microsystems and AT&T....
. Running AT&T
AT&T

AT&T Inc. is the largest US provider of both local and long distance telephone services, and Digital subscriber line Internet access. AT&T is the second largest provider of wireless service in the United States, with over 77 million wireless customers, and more than 150 million total customers....
 UNIX
Unix

Unix is a computer operating system originally developed in 1969 by a group of American Telephone & Telegraph employees at Bell Labs, including Ken Thompson , Dennis Ritchie, Douglas McIlroy, and Joe Ossanna....
 System V R4, the system was equipped with 68020 or 68030 CPU accelerator card, SCSI
SCSI

Small Computer System Interface, or SCSI , is a set of standards for physically connecting and transferring data between computers and peripheral devices....
 controller card, Texas Instruments
Texas Instruments

Texas Instruments , better known in the electronics industry as TI, is an United States company based in Dallas, Texas, Texas, United States, renowned for developing and commercializing semiconductor and computer technology....
 TIGA
Texas Instruments Graphics Architecture

Texas Instruments Graphics Architecture was a graphics interface standard created by Texas Instruments that defined the software interface to graphics processors....
 24bit graphic card capable to show 256 colors on screen, and a three buttons mouse.
X11R5September 5, 1991PEX
PHIGS

PHIGS is an application programming interface standard for rendering 3D computer graphics, at one time considered to be the 3D graphics standard for the 1990s....
, Xcms (color management
Color management

In digital imaging systems, color management is the controlled conversion between the color representations of various devices, such as s, digital cameras, monitors, TV screens, film printers, computer printers, offset presses, and corresponding media....
), font server
X Font Server

The X font server provides a standard mechanism for an X server to communicate with a font Font rendering, frequently one running on a remote machine....
, X386
XFree86

XFree86 is an implementation of the X Window System. It was originally written for Unix-like operating systems on IBM PC compatibles and is now available for many other operating systems and platforms....
, X video extension
X video extension

The X video extension, often abbreviated as XVideo or Xv, is a video output mechanism for the X Window System. The protocol was designed by David Carver; the specification for version 2 of the protocol was written in July 1991....
X11R6May 16, 1994ICCCM v2.0; Inter-Client Exchange; X Session Management; X Synchronization extension; X Image extension
X Image Extension

X Image Extension, or XIE was an extension to the X Window System to enhance its Computer graphics capability. It was intended to provide a powerful mechanism for the transfer and display of virtually any image on any X-capable hardware....
; XTEST extension; X Input; X Big Requests; XC-MISC; XFree86 changes.
X11R6.1March 14, 1996X Double Buffer extension; X keyboard extension
X keyboard extension

In the X Window System, the X keyboard extension or XKB extends the ability to control the computer keyboard over what is offered by the X Window System core protocol....
; X Record extension.
X11R6.2
X11R6.3 (Broadway)
December 23, 1996Web functionality, LBX
Low Bandwidth X

In computing, LBX, or Low Bandwidth X, was a protocol to use the X Window System over computer network links with low Bandwidth and high Lag....
. Last X Consortium release. X11R6.2 is the tag for a subset of X11R6.3 with the only new features over R6.1 being XPrint and the Xlib implementation of vertical writing and user-defined character support.
X11R6.4March 31, 1998Xinerama
Xinerama

Xinerama is an extension to the X Window System which enables Multi-monitor X applications and window managers to use two or more physical displays as one large virtual display....
.
X11R6.5 Internal X.org release; not made publicly available.
X11R6.5.1August 20, 2000 
X11R6.6April 4, 2001Bug fixes, XFree86 changes.
X11R6.7.0April 6, 2004First X.Org Foundation release, incorporating XFree86 4.4rc2. Full end-user distribution. Removal of XIE
X Image Extension

X Image Extension, or XIE was an extension to the X Window System to enhance its Computer graphics capability. It was intended to provide a powerful mechanism for the transfer and display of virtually any image on any X-capable hardware....
, PEX
PHIGS

PHIGS is an application programming interface standard for rendering 3D computer graphics, at one time considered to be the 3D graphics standard for the 1990s....
 and libxml2.
X11R6.8.0September 8, 2004Window translucency, XDamage, Distributed Multihead X, XFixes
XFixes

In computing, XFixes is an X Window System extension which makes useful additions to the X11 protocol. It was started in 2003 by Keith Packard. It first appeared in the KDrive X server and later in X.Org Server version 6.8.0....
, Composite, .
X11R6.8.1September 17, 2004Security fix in libxpm
XPM (image format)

X Pixmap is an American Standard Code for Information Interchange-text-based image format used by the X Window System. It was created in 1989 by Daniel Dardailler and Colas Nahaboo working at Bull Research Center at Sophia Antipolis, France, and was later enhanced by Arnaud Le Hors....
.
X11R6.8.2February 10, 2005Bug fixes, driver updates.
X11R6.9
X11R7.0
December 21, 2005EXA
Exa

exa is a SI prefix in the SI system of Units of measurements denoting 1 E18 or 1 000 000 000 000 000 000.Adopted in 1975, it comes from the Greek language ??, meaning six , because it is equal to 10006....
, major source code refactoring. From the same source-code base, the modular autotooled
GNU build system

The GNU build system, also known as the Autotools, is a suite of programming tools produced by the GNU project. These tools are designed to assist in making various source code Software package porting to many Unix-like systems....
 version became 7.0 and the monolithic imake
Imake

imake is a discontinued build automation implemented on top of the C preprocessor.imake generates makefiles from a template, a set of C preprocessor macro functions, and a per-directory input file called an Imakefile....
 version was frozen at 6.9.
X11R7.1May 22, 2006EXA enhancements, KDrive
KDrive

KDrive was a small X Window System server implementation created by Keith Packard. Unlike the X.Org Server, KDrive was not based on XFree86 code....
 integrated, AIGLX
AIGLX

Accelerated Indirect GLX is an open source project founded by Red Hat and the Fedora community to allow accelerated indirect GLX rendering capabilities to X.Org and Direct Rendering Infrastructure drivers....
, OS and platform support enhancements.
X11R7.2February 15, 2007Removal of LBX and the built-in keyboard driver, X-ACE, XCB
XCB

In computing, XCB is a C binding for the X Window System. It is implemented as free software and aims to replace Xlib. The project was started in 2001 by Bart Massey....
, autoconfig improvements, cleanups.
X11R7.3September 6, 2007XServer 1.4
X.Org Server

The X.Org Server is the X server in the official reference implementation of the X Window System. The current stable release is 1.6.0, which is part of X11R7.5, and was released on 25 February 2009....
, Input hotplug, output hotplug (RandR
RandR

The X Window System Resize and Rotate Extension allows clients to dynamically change X screens, so as to resize, rotate and reflect the root window of a screen....
 1.2), DTrace
DTrace

DTrace is a comprehensive dynamic Tracing framework created by Sun Microsystems for troubleshooting kernel and application problems on production systems in real time....
 probes, PCI
Peripheral Component Interconnect

The PCI Local Bus , or Conventional PCI, is a computer bus for attaching computer hardware in a computer. These devices can take either the form of an integrated circuit fitted onto the motherboard itself, called a planar device in the PCI specification or an expansion card that fits into a socket....
 domain support.
X11R7.4September 23, 2008XServer 1.5.1
X.Org Server

The X.Org Server is the X server in the official reference implementation of the X Window System. The current stable release is 1.6.0, which is part of X11R7.5, and was released on 25 February 2009....
, XACE, PCI-rework, EXA speed-ups, _X_EXPORT, GLX
GLX

GLX provides the Binding connecting OpenGL and the X Window System: it enables programs wishing to use OpenGL to do so within a window provided by the X Window System....
 1.4, faster startup and shutdown.


Forthcoming releases


VersionRelease dateMost important planned changes
X11R7.5roughly June-July 2009 XServer 1.7
X.Org Server

The X.Org Server is the X server in the official reference implementation of the X Window System. The current stable release is 1.6.0, which is part of X11R7.5, and was released on 25 February 2009....
, XKB 2 and Xi 2, XGE, RandR
RandR

The X Window System Resize and Rotate Extension allows clients to dynamically change X screens, so as to resize, rotate and reflect the root window of a screen....
 1.3 (GPU object), MPX, predictable pointer acceleration, DRI
Direct Rendering Infrastructure

In computing, the Direct Rendering Infrastructure is an interface and a free software implementation used in the X Window System to securely allow user applications to access the video hardware without requiring data to be passed through the X server....
 memory manager, DRI2, Shatter, further removal of obsolete libraries and extensions.


See also


  • History of the graphical user interface
    History of the graphical user interface

    The graphical user interface, understood as the use of graphic icons and a pointing device to control a computer, has over the last four decades a steady history of incremental refinements built on some constant core principles....
  • X11 color names
    X11 color names

    In computing, on the X Window System, X11 color names are represented in a simple text file, which maps certain strings to RGB color values. It is shipped with every "X" installation, hence the name, and is usually located in <X11root>/lib/X11/rgb.txt....
  • Xgl
    Xgl

    Xgl is an X Window System architecture designed to take advantage of modern graphics cards via their OpenGL drivers, layered on top of OpenGL via Glitz ....
  • General Graphics Interface
    General Graphics Interface

    General Graphics Interface is a project that aims to develop a reliable, stable and fast computer graphics system that works everywhere. The intent is to allow for any program using GGI to run on any computing platform supported by it, requiring at most a recompile....
  • VirtualGL
    VirtualGL

    VirtualGL is an open source program which redirects the 3D rendering commands from Unix and Linux OpenGL applications to 3D accelerator hardware in a dedicated server and displays the rendered output interactively to a thin client located elsewhere on the network....
  • rio (program)
    Rio (program)

    rio is Plan 9 from Bell Labs's windowing system.Many of its features embody key Plan 9 design concepts:* Each Window runs in its own private namespace ....
  • List of Unix programs
    List of Unix programs

    This is a list of UNIX utilities as specified by IEEE Std 1003.1-2004, which is part of the Single UNIX Specification .These utilities can be found on UNIX Operating systems and most UNIX-like operating systems....
  • DESQview/X
  • Cairo (graphics)
    Cairo (graphics)

    cairo is a software library used to provide a vector graphics-based, device-independent Application programming interface for software developers....
  • Y Window System
    Y Window System

    The Y Window System is a windowing system, consisting of a window Server and a client Library for writing applications. It was written by Mark Thomas as the subject of his Master's thesis at Imperial College, London....
  • XFree86
    XFree86

    XFree86 is an implementation of the X Window System. It was originally written for Unix-like operating systems on IBM PC compatibles and is now available for many other operating systems and platforms....


External links

  • Official website
  • (Jon Smirl, 30 August 2005)
  • RFC 1198 - FYI on the X Window System