X Windows, or X.Org, is the graphical system widely used by GNU/Linux and UNIX Operating Systems.
Usually Linux machines and Apple OSX have a native system that would allow a client to remotely login and execute X.Org programs on her own machine.
Unfortunately this is not the case for MicroSoft Windows (also called MS Windows in this document); one needs to install additional software for remote applications to open windows in the Microsoft graphical environment.
There are plenty of software out there, the mostly used being:
I used to use Xming, but has been reported to have some quirks with newer versions of windows, so I investigated some new ones and I am now using VcXsrv.
This page will show how to use this software together with another well known remote access software, Putty.
If you want a non open-source version but very user friendly, without the need for PuTTY, have a look at
A typical remote access from MS Windows to some X-Windows enabled server (i.e. running Linux or UNIX) will include: