These frame parameters give the most basic information about the
name are meaningful on all terminals.
niltitle, it appears in the window system's title bar at the top of the frame, and also in the mode line of windows in that frame if
mode-line-frame-identificationuses ‘%F’ (see %-Constructs). This is normally the case when Emacs is not using a window system, and can only display one frame at a time. See Frame Titles.
titleparameter is unspecified or
nil. If you don't specify a name, Emacs sets the frame name automatically (see Frame Titles).
If you specify the frame name explicitly when you create the frame, the name is also used (instead of the name of the Emacs executable) when looking up X resources for the frame.