WEBBOverview. Cygwin/X is a port of the X Window System to the Cygwin API layer for the Microsoft Windows family of operating systems. Cygwin provides a UNIX-like API, thereby minimizing the amount of porting required. Cygwin/X consists of an X server, X libraries, and nearly all of the standard X clients, such as xterm, xhost, xdpyinfo, xclock ...