KDE, or "K" for short, is a windows manager for the X window system in *nix. Without window managers like KDE or Gnome, the *nix GUI would be rather bleak. KDE is currently developing the next version of it's software, KDE 4. In this version, there will be a multi-lingual spell checker built into the window manager. There will also be much better support for hardware, and a gigantic tweak of the software that allows for interoperability between a Windows/Mac system and a *nix system. There is also "Dolphin", the new file manager. You can get more details of KDE4 off of dot.kde.org.