Xfce

Xfce is a free and open-source desktop environment for Unix and Unix-like operating systems, such as Linux, Solaris, and BSD.

Xfce aims to be fast and lightweight, while still being visually appealing and easy to use. Xfce embodies the traditional UNIX philosophy of modularity and re-usability. It consists of separately packaged parts that together provide all functions of the desktop environment, but can be selected in subsets to suit user needs and preference. Another priority of Xfce is adherence to standards, specifically those defined at freedesktop.org.