A X server is needed on Windows if you SSH to remote Linux computers and wish to start X or GUI applications from there. It is also necessary if you are working with a Linux distribution running inside Windows Subsystem for Linux (WSL). VcXsrv is a free open-source X server that can be used for all these purposes.
$ export DISPLAY=localhost:0.0
Launch any X or GUI app and its window should now be displayed in its own individual Windows window.
-Y. On the remote system, set the
$ export DISPLAY=your-windows-ip:0.0
When you start XLaunch you may want to choose to Disable access control. Otherwise you may get errors like this:
$ xeyes Authorization required, but no authorization protocol specified Error: Can't open display: 10.0.0.99:0.0
Tried with: VcXsrv 184.108.40.206 and Ubuntu 18.04 WSL