The Xming program is better known as a display server. It is public domain software and it works on Windows as a stand-alone program which means you do not need an emulator. It is a free X server that has been in circulation since 2007. It receives occasional updates but you may have to tweak it yourself to bring it up to date with the most recent version of Windows.
A Native Program That Runs On Windows
Xming gives your X Window System display server a number of sample X tools and applications (traditional ones). It also gives your display server a set of fonts. The display server supports a number of different languages. It also has OpenGL GLX 3D graphics extensions and Mesa 3D capabilities. You may use Xming to run SSH (Secure Shell) in a secure fashion in order to forward X11 sessions from your other computers. The display server is cross-compiled on Linux and it has a MinGW compiler suite. It also comes with the famous Pthreads-Win32 multi-threading library.
Conclusion - Great If A Free X Server Is Needed
Xming X server is based on Cygwin/X with one of the main differences being that it is less configurable. It is free it is simple to use compared to Cygwin/X and it is certainly easier to install than Cygwin/X. If you wish to update it yourself to bring it up to date with your current version of Windows then you are allowed because the release is classified as public domain software.