Enlightenment, also known simply as E, is a stacking window manager for the X Window System which can be used alone or in conjunction with a desktop environment such as GNOME or KDE. Enlightenment is often used as a substitute for a full desktop environment.
The first version of Enlightenment was released by Rasterman (Carsten Haitzler) in 1997. Version 0.17, also referred to as DR17 or E17, has been in development since December 2000. It is a complete rewrite on DR16 and was designed to be a full-fledged desktop shell, based on the new Enlightenment Foundation Libraries (EFL).
Enlightenment 0.17 (a.k.a E17) released on December 21st 2012.
For more information about Enlightenment, visit http://enlightenment.org/