Straight servers, as opposed to development servers, generally do not require a display manager. Of course, development servers and those servers that do provide the ability to log in to a managed display environment do require both a display manager and a window manager. The former handles the creation and security of the X-Windows display environment and resources required, while the latter handles the actual desktop environment presented to the user.
There are several major environments, each with its associated Display and Window Managers. The two major environments are GNOME and KDE. Both support a variety of graphic toolkit libraries, so that most applications that run in one will run in the other, provided the necessary services are available. These services are usually installed as a dependency when the application is installed ifyou don't install the basic meta package for either GNOME or KDE. So if, for example, you like the KcacheGrind tool for browsing program profiling data, but are using GNOME, you can go ahead and install and use it under GNOME. It will work fine. Likewise, ifyou prefer the K Display Manager (KDM) that comes with KDE to the GNOME Display Manager (GDM) provided by GNOME, it will work just as well.
Given this interoperability, why choose one over the other? It is mostly a matter of personal preference. As mentioned in the first chapter, KDE is usually preferred by European users, while GNOME is more of an American preference. Our main concern in this section will be where to find configuration files or applications for each.
Where did my desktop go?
Both GNOME and KDE, like the new Windows 8, have abandoned the old desktop metaphor for a more activity or task oriented look. It takes some getting used to and Can be disconcerting at first. Covering the changes from the old look to the new would take a book for each Desktop Manager! However, the home sites for both KDE and GNOME provide tutorials and documentation to help you get started. If you prefer the older desktop metaphor, both GNOME and KDE provide ways to set this up as well.
