From LQWiki

A GUI is a Graphical User Interface, sometimes pronounced "gooey". This is what a user interacts with, what provides users buttons, lists, text, menus, etc. Similar to UI (User Interface) but with the added coolness of being graphically based.

GUI components include:

• A context for rendering graphics, like the X Window System
• "Toolkits" such as GTK, Motif and Qt
• A window manager
• In many cases, a higher-level desktop environment such as GNOME or KDE
• End-user applications

Unlike OS X and Windows, there is no single standard for any of these components; generally, two or three competing software packages exist at each level. On the one hand, this allows distributions to customize the Linux desktop as they wish. On the other, this leads to incompatibility, as different apps cannot effectively interoperate.

The freedesktop.org site acts as a clearing-house and collaboration nexus for recent experiments with new GUI paradigms, protocols and programs. The site also hosts documentation for implementing accepted standards, such as drag-n-drop, and clipboard functionality.

See also

• General Tips - despite the article's name, this is a list of tips for dealing with X