In Unix computing, Ion (aka IonWM) is a tiling and tabbing window manager for the X Window System. It is designed such that it is possible to manage windows using only a keyboard, without needing a mouse. It is the successor of PWM and is written by the same author. Since the first release of Ion in the summer 2000, similar alternative window management ideas have begun to show in other new window managers: Larswm, ratpoison, StumpWM, WMI, and TrsWM. Wikipedia
The definitive Wikipedia entry for Ion. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Ion_%28window_manager%29