GNOME is a desktop environment and graphical user interface that runs on top of a computer operating system. It is composed entirely of free and open source software and is developed by both volunteers and paid contributors, the largest corporate contributor being Red Hat. It is an international project that includes creating software development frameworks, selecting application software for the desktop, and working on the programs that manage application launching, file handling, and window and task management.
GNOME is part of the GNU Project and can be used with various Unix-like operating systems, most notably GNU/Linux and as part of OpenSolaris Desktop.
GNOME was started in August 1997 by Miguel de Icaza and Federico Mena as a free software project to develop a desktop environment and applications for it. It was founded in part because K Desktop Environment, an already existing free software desktop environment, relied on the Qt widget toolkit which at the time used a proprietary software license. In place of Qt, the GTK+ toolkit was chosen as the base of GNOME. GTK+ uses the GNU Lesser Public License (LGPL), a free software license that allows software linking to it to use a much wider set of licenses, including proprietary software licenses. GNOME itself is licensed under the LGPL for its libraries, and the GNU General Public License (GPL) for its applications.
The California startup Eazel developed the Nautilus file manager from 1999 to 2001. De Icaza and Nat Friedman founded Helix Code (later Ximian) in 1999 in Massachusetts. The company developed GNOME's infrastructure and applications, and in 2003 was purchased by Novell.
GNOME 2 (the previous major release) was very similar to a conventional desktop interface, featuring a simple desktop in which users could interact with virtual objects, such as windows, icons, and files. GNOME 2 used Metacity as its default window manager. The handling of windows, applications, and files in GNOME 2 is similar to that of contemporary desktop operating systems. In the default configuration of GNOME 2, the desktop has a launcher menu for quick access to installed programs and file locations; open windows may be accessed by a taskbar along the bottom of the screen, and the top-right corner features a notification area for programs to display notices while running in the background. However, these features can be moved to almost any position or orientation the user desires, replaced with other functions or removed altogether.
(Text from the wikipedia article, image from gnome.org)