The X Window System provides a state-of-the-art graphical user interface and offers features not found in other GUI environments. Although the X Window System can be complicated, you should be able to configure it during the RHEL installation process. Alternatively, the Red Hat Display Settings tool simplifies the setup or reconfiguration process.
One of the key parts of the X Window System is the X Font Server. If it isn't running, or the /tmp or /home directory partitions are full, you can't run the Linux GUI.
The X Window System works as client and server. X clients and X servers can be located on different computers on a network. With an appropriate firewall configuration, you can take advantage of it with the Secure Shell.
The look and feel of the X Window interface is determined by your choice of desktop. RHEL comes with several desktop environments, including GNOME, KDE, and twm; the default is GNOME.
You can customize the GUI start process in a number of ways. You can configure a default login manager. With an appropriate .xinitrc file, you can set up X clients to start when you run the startx command. Plus, you can configure a default desktop with the switchdesk command, which defined it in the local .Xclients-default file. Alternatively, you can run the Sessions utility to configure X clients in the GNOME desktop.