KDE is the K Desktop Environment. It is a project initiated by Matthias Ettrich in 1996. The aim of the KDE project is to connect the power of the UNIX® operating systems with the comfort of a modern user interface.

In short, KDE will bring UNIX® to the desktop!

If you want further information about KDE, have a look at What is KDE?

KDE is a Desktop Environment for all flavors of UNIX®. While it is true that most KDE developers use Linux®, KDE runs smoothly on a wide range of systems. You may, however, need to tweak the source code a bit to get KDE to compile on a not-so-popular variant of UNIX®, or if you are not using the GNU development tools, in particular the gcc compiler.

No, KDE is not a window manager. While KDE includes a very sophisticated window manager (KWin), KDE is much more than that. It is a full-blown Integrated Desktop Environment.

KDE provides a complete desktop environment, including a web browser, a file manager, a window manager, a help system, a configuration system, uncountable tools and utilities, and an ever increasing number of applications, including but not limited to mail and news clients, drawing programs, a PostScript® and a DVI viewer and so forth.

No, KDE is not a clone. Specifically KDE is not a CDE or Windows® clone. While the KDE developers have and will continue to glean the best features from all existing desktop environments, KDE is a truly unique environment that has and will continue to go its own way.

Yes, KDE is free software according to the GNU General Public License. All KDE libraries are available under the LGPL making commercial software development for the KDE desktop possible, but all KDE applications are licensed under the GPL.

KDE uses the Qt™ C++ crossplatform toolkit, which is also released (since version 2.2) under the GPL.

It is absolutely legal to make KDE and Qt™ available on CD-ROM free of charge. No runtime fees of any kind are incurred.