A frame is a rectangle on the screen that contains one or more Emacs windows. A frame initially contains a single main window (plus perhaps a minibuffer window), which you can subdivide vertically or horizontally into smaller windows.
When Emacs runs on a text-only terminal, it starts with one terminal frame. If you create additional ones, Emacs displays one and only one at any given time—on the terminal screen, of course.
When Emacs communicates directly with a supported window system, such as X, it does not have a terminal frame; instead, it starts with a single window frame, but you can create more, and Emacs can display several such frames at once as is usual for window systems.
This predicate returns a non-
nilvalue if object is a frame, andnilotherwise. For a frame, the value indicates which kind of display the frame uses:
x- The frame is displayed in an X window.
t- A terminal frame on a character display.
mac- The frame is displayed on a Macintosh.
w32- The frame is displayed on MS-Windows 9X/NT.
pc- The frame is displayed on an MS-DOS terminal.
See Display, for information about the related topic of controlling Emacs redisplay.