Xfce is a desktop environment for Unix and other Unix-like platforms, such as Linux, Solaris or BSD. Its configuration is entirely mouse-driven; the configuration files are hidden from the casual user. “Designed for productivity, it loads and executes applications fast, while conserving system resources.” (Olivier Fourdan, creator)
Xfce is based on the GTK+ 2.x toolkit (like GNOME). It uses the Xfwm window manager. Xfce is somewhat similar to the commercial CDE, but has been getting a little farther away from that comparison with each new version (it was completely re-written twice, between versions 2 and 3, and then again for version 4).
The name “Xfce” originally stood for “XForms Common Environment”, but since that time Xfce has been rewritten twice and does not use the XForms toolkit any more. The name survived, but it is no longer capitalized as “XFce”, but “Xfce”. The developers' current stance is that the acronym does not stand for anything any more. The installer for the Xfce and Slackware-based distro Zenwalk labels the description for Xfce as the “Cholesterol Free Desktop Environment” as Slackware has done in the past.
Xfce is not as common in Linux distributions as KDE and GNOME. Few distributions include Xfce as their default desktop environment, though most include it as an optional component. Some distributions which include Xfce by default: