Editing X display manager (section)

{{Short description|Login manager on an X Window System server}}
{{for|the program called 'X Display Manager'|XDM (display manager)}}
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In the [[X Window System]], an '''X display manager''' is a graphical [[login manager]] which starts a [[login session]] on an [[X Window System|X server]] from the same or another [[computer]].

[[Image:Simple-desktop-display-manager.jpg|thumb|350px|A login screen shown by the [[Simple Desktop Display Manager|SDDM]] display manager.]]

A display manager presents the user with a [[login|login screen]]. A session starts when a user successfully enters a valid combination of [[username]] and [[password]].

When the display manager runs on the user's computer, it starts the X server before presenting the user the login screen, optionally repeating when the user logs out. In this condition, the DM realizes in the X Window System the functionality of {{mono|[[getty (Unix)|getty]]}} and {{mono|login}} on [[computer terminal|character-mode terminals]]. When the display manager runs on a remote computer, it acts like a [[telnet]] server, requesting username and password and starting a remote session.

X11 Release 3 introduced display managers in October 1988 with the aim of supporting the standalone [[X terminal]]s, just coming onto the market. Various display managers continue in routine use to provide a graphical login prompt on standalone [[computer workstation]]s running X. X11R4 introduced the '''X Display Manager Control Protocol''' ('''XDMCP''') in December 1989 to fix problems in the X11R3 implementation.