The prefix key C-x 5 is analogous to C-x 4. Whereas each C-x 4 command pops up a buffer in a different window in the selected frame (see Displaying in Another Window), the C-x 5 commands use a different frame. If an existing visible or iconified (a.k.a. “minimized”, see Visibility of Frames in The Emacs Lisp Reference Manual) frame already displays the requested buffer, that frame is raised and deiconified (“un-minimized”); otherwise, a new frame is created on the current display terminal.
The various C-x 5 commands differ in how they find or create the buffer to select:
Create a new frame using the default frame parameters
Create a new frame using the window configuration and frame parameters
of the current frame (
Select buffer bufname in another frame. This runs
Visit file filename and select its buffer in another frame. This
find-file-other-frame. See Visiting Files.
Select a Dired buffer for directory directory in another frame.
dired-other-frame. See Dired, the Directory Editor.
Start composing a mail message in another frame. This runs
compose-mail-other-frame. It is the other-frame variant of
C-x m. See Sending Mail.
Find the definition of an identifier in another frame. This runs
xref-find-definitions-other-frame, the multiple-frame variant
of M-.. See Find Identifier References.
Visit file filename read-only, and select its buffer in another
frame. This runs
See Visiting Files.
A more general prefix command that affects the buffer displayed by the
next command invoked immediately after this prefix command
other-frame-prefix). It requests the buffer of the next
command to be displayed in another frame.
You can control the appearance and behavior of the newly-created frames by specifying frame parameters. See Frame Parameters.