Why do X Window System applications fail to work?
If you are logging in from a system running a non-Unix operating system (e.g., Microsoft Windows), you need a secure-shell client that supports the X Window System; the cygwin system can do this. From Apple Macintosh systems, you need to install the optional X Window System support, and then click on the X11 icon before making the secure-shell connection. The X Window System system is powerful, and allows the application, the window manager, and the display to be on as many as three separate machines. In order to determine where to send window-system output, you must identify the local machine (the one with the display, keyboard, and mouse).
