A frame is a screen object that contains one or more Emacs windows (see Windows). It is the kind of object called a “window” in the terminology of graphical environments; but we can’t call it a “window” here, because Emacs uses that word in a different way. In Emacs Lisp, a frame object is a Lisp object that represents a frame on the screen. See Frame Type.
A frame initially contains a single main window and/or a minibuffer window; you can subdivide the main window vertically or horizontally into smaller windows. See Splitting Windows.
A terminal is a display device capable of displaying one or more Emacs frames. In Emacs Lisp, a terminal object is a Lisp object that represents a terminal. See Terminal Type.
There are two classes of terminals: text terminals and
graphical terminals. Text terminals are non-graphics-capable
displays, including xterm and other terminal emulators. On
a text terminal, each Emacs frame occupies the terminal’s entire
screen; although you can create additional frames and switch between
them, the terminal only shows one frame at a time. Graphical
terminals, on the other hand, are managed by graphical display systems
such as the X Window System, which allow Emacs to show multiple frames
simultaneously on the same display.
On GNU and Unix systems, you can create additional frames on any available terminal, within a single Emacs session, regardless of whether Emacs was started on a text or graphical terminal. Emacs can display on both graphical and text terminals simultaneously. This comes in handy, for instance, when you connect to the same session from several remote locations. See Multiple Terminals.
This predicate returns a non-nil value if object is a
frame, and nil otherwise. For a frame, the value indicates which
kind of display the frame uses:
tThe frame is displayed on a text terminal.
xThe frame is displayed on an X graphical terminal.
w32The frame is displayed on a MS-Windows graphical terminal.
nsThe frame is displayed on a GNUstep or Macintosh Cocoa graphical terminal.
pcThe frame is displayed on an MS-DOS terminal.
pgtkThe frame is displayed using pure GTK facilities.
This function returns the terminal object that displays frame.
If frame is nil or unspecified, it defaults to the
selected frame.
This predicate returns a non-nil value if object is a
terminal that is live (i.e., not deleted), and nil otherwise.
For live terminals, the return value indicates what kind of frames are
displayed on that terminal; the list of possible values is the same as
for framep above.
On a graphical terminal we distinguish two types of frames: A normal top-level frame is a frame whose window-system window is a child of the window-system’s root window for that terminal. A child frame is a frame whose window-system window is the child of the window-system window of another Emacs frame. See Child Frames.