Xdm manages a collection of X servers, which may be on the local host or remote machines. It provides services similar to those provided by init, getty, and login on character-based terminals: prompting for login name and password, authenticating the user, and running a session. xdm supports XDMCP (X Display Manager Control Protocol) and can also be used to run a chooser process which presents the user with a menu of possible hosts that offer XDMCP display management.