X Window System

GNOME 2.20

KDE 4

Xfce 4.4

The X Window System is software for a graphical user interface (GUI) system. It is a set of protocols and programs. It is also known as X11, or just X. It can manage windows, and other parts of a graphical user interface (GUI) on a bitmap display. The X Window System is commonly found in Unix-like operating systems.

X provides the basic components to build GUI environments: drawing and moving windows on the screen and interacting with a mouse or a keyboard. X does not say what the user interface should look like. X only draws, so different client programs handle this. Different X11-based environments can have different designs. X usually is not a part of an operating system; instead, it is built as an additional program on top of the operating system.

Unlike display protocols from before, X was specifically designed to be used over network connections rather than on a display near the computer. X has network transparency: the machine where an application program (the client application) runs need not be the user's local machine (the display server).

X was developed at MIT in 1984. The current protocol version, X11, appeared in September 1987. The X.Org Foundation leads the X project, with the current reference implementation, version 11 release 7.7 (6 June 2012), available as free software under the MIT License and similar permissive licenses.

Limitations and criticism

Issues for disabled people

Systems that rely on X can have accessibility issues. This makes using a computer hard for some people, especially those who are disabled. There are no accessibility standards or guidelines for X11. This forces other projects to implement accessibility for X.

Security

Sandboxing prevents bad programs from accessing your personal files or crashing your system. X's design lacks this, so any program can access and even fake keyboard and mouse presses, or the clipboard content.

This is particularly dangerous when X11 is ran as root, the account that has the most permissions. This makes applications have the ability to access your entire system. In the past, this method was used because some systems were configured to run X11 as root.