The XFree86 Project, Inc is a global volunteer organization which produces XFree86®, the freely redistributable open-source implementation of the X Window System continuously since 1992.
XFree86 runs primarily on UNIX® and UNIX-like operating systems like Linux, all of the BSD variants, Sun Solaris both native 32 and 64 bit support, Solaris x86, Mac OS X (via Darwin), SGI's Irix as well as other platforms like OS/2 and Cygwin.
What XFree86 does, is provide a client/server interface between the display hardware (those physical things like the mouse, keyboard, and video displays) and the desktop environment, (this is typically called a window manager as it deals with how X is displayed i.e. the overall appearance). Yet X it goes beyond that and also gives the infrastructure and a sta