XFree86

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XFree86

The X server is the common graphical interface for Unix-like systems. The XFree86 project started off as X386, a reference implementation of this protocol, but was so good that it's still in use today.

XFree86 was once by far the most popular X server for Linux; after a developer interaction problem, though, most distros switched over to competing project X.org

ConfiguringXFree86
Alternatives to XFree86
http://www.xfree86.org