What is XFree86?
From: XFree86.org web site “The XFree86 Project, Inc is the “organisation which produces XFree86, a freely redistributable open-source implementation of the X Window System which runs on UNIX(R) and UNIX-like operating systems such as Linux, all of the BSD variants, Sun Solaris x86, Mac OS X (via Darwin), as well as other platforms like OS/2 and Cygwin.” Summary: Just as the Classic environment makes it possible to run classic Mac OS applications in Mac OS X, so does Xfee86 make it possible to run X11 applications in Mac OS X. Apple’s X11 has radically simplified the process of installing this environment.