This article is from the GNU Chess and XBoard FAQ, by Tim Mann firstname.lastname@example.org with numerous contributions by others.
XBoard and WinBoard have three major modes that can't be changed from
the menus: local chess engine mode, ICS mode, and standalone mode.
With XBoard, you have to set the mode using command-line options. Local
chess engine mode is the default, -ics selects ICS mode, and -ncp ("no
chess program") selects standalone mode.
With WinBoard, if you don't set the mode using command-line options, you
get a dialog box asking which mode you want. To bypass the dialog box,
use -cp ("chess program") for local chess engine mode, or -ics or -ncp
as with XBoard. Also see topic [E.7] .