GNOME, KDE and Xfce are the most popular desktop environments for Linux. Most people end up using the default desktop environment that ships with their preferred Linux distribution. But experienced users prefer one over the year for either usability, performance, design or customizability considerations.
GNOME began as a project to develop a free and open-source desktop environment and corresponding applications in August 1997. Its design philosophy can be best described as streamlined and easy to use.
KDE community started in October 1996. Its design philosophy is dedicated to functionality and expansion of its features.
This comparison is a wiki. Please feel free to improve the comparison chart or the description below it.
Comparison chart
 | GNOME | KDE |
|---|---|---|
| Introduction (from Wikipedia) | GNOME (GNU Network Object Model Environment) is a desktop environment—a graphical user interface that runs on top of a computer operating system—composed entirely of free and open source software. | KDE is a desktop environment for an integrated set of cross-platform applications designed to run on Linux, FreeBSD, Microsoft Windows, Solaris and Mac OS, designed by the KDE Community. |
| Focus | Free software | Free software |
| Developer | The GNOME Project | KDE |
| Website | GNOME.org | kde.org |
| Founded | 1999 | 1996 |
| Current Stable Release | 3.10 (September 26, 2013) | 4.11 (August 14, 2013) |
| Minimum System Requirements | 700 Mhz CPU, 768 MB RAM | 1 Ghz CPU, 615 MB RAM |
| Design Goals | A top-to-bottom free desktop environment designed for simplicity, accessibility, and ease of internationalization and localization. | A one-stop, integrated desktop environment; carrying out day-to-day tasks without reliance on command-line interface. |
| Motto | An intuitive and attractive desktop for users | Experience Freedom! |
| Toolkit | GTK+ | Qt |
| Founder(s) | Miguel de Icaza and Federico Mena |
