By default a full installation of Debian 9 Linux will have the graphical user interface (GUI) installed and it will load up after system boot, however if we have installed Debian without the GUI we can always install it later, or otherwise change it to one that is preferred.
This quick guide will cover how to install LXDE on Debian 9 Stretch, which will provide a GUI for working with the Linux system. While I don’t suggest using a GUI on a production server, it’s a good option if you’re using Debian as a desktop.