A desktop environment may recommend a particular display manager, but this does not mean that it will not work with another display manager. If you have ever installed more than one desktop environment on the same system, you may remember that a login screen (i.e. the display manager) allows you to switch desktop environments.
A display manager can be used with multiple desktop environments
Although the display manager is not part of the desktop environment, it is often developed by the same team as the desktop environment. It also becomes part of the desktop environment's identity.
For example, GNOME desktop environment france email list develops GDM (GNOME Display Manager) and just by looking at the login screen, you would think of GNOME desktop environment.
GNOME login screen with GDM
Some popular display managers are:
GDM (GNOME Display Manager) - Preferred by GNOME
SDDM (Simple Desktop Display Manager) - Preferred by KDE
LightDM: developed by Ubuntu for Unity desktop
Display managers can be customized
There are many desktop environments available. Do they all have their own display managers? No, that is not the case.
As I mentioned earlier, the visible login screen is called a greeter. This greeting can be customized to change the look of the login screen.Paul Samuelson and William Nordhous in their 18th edition of their book Economics say that economics is the study of how societies use scarce resources to produce valuable goods and distribute them among different people. Gregory Makiw defines it in even simpler terms:
