The modern X.Org Foundation came into being in 2004 when the body that oversaw X standards and published the official reference implementation joined forces with former XFree86 developers.
X11R6.7.0, the first version of the X.Org Server, was forked from XFree86 4.4 RC2. The immediate reason for the fork was a disagreement with the new license for the final release version of XFree86 4.4, but several disagreements among the contributors surfaced prior to the split. Many of the previous XFree86 developers have joined the X.Org Server project.
The X11R6.9.0/X11R7.0.0 release primarily added a modular build system based on the GNU Autotools. 6.9.0 used the old imake build system whereas 7.0.0 uses autotools, both on the same codebase. The modular path (using GNU Autotools) is however the future direction of the X.Org server, and also saw the X11 binaries moving out of their own /usr/X11R6 subdirectory tree and into the global /usr tree on POSIX systems.
Adoption
The X.Org Server is increasingly popular with the free software Unix-like operating systems, being adopted in most Linux distributions and BSD variants, with the exception of NetBSD (although X.org is available via pkgsrc). It is also included in Sun Microsystems' Solaris, and is the server of choice for x86 systems; SPARC-based systems almost exclusively use Sun's proprietary Xsun server, as SPARC graphics driver support for X.org is very limited. It is also used in Cygwin/X, Cygwin's implementation of the X server for Microsoft Windows, and in Xming. Mac OS X versions prior to 10.5 ("Leopard") ship with an XFree86-based X window server, but 10.5's X server is based on the X.org codebase.[2]
