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 (Pop Up Window), the C-x 5 commands use a different frame. If an existing visible or iconified (a.k.a. ``minimized'', Visibility of Frames) 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:

C-x 5 2

Create a new frame using the default frame parameters (make-frame-command).

C-x 5 c

Create a new frame using the window configuration and frame parameters of the current frame (clone-frame).

C-x 5 b bufname RET

Select buffer bufname in another frame. This runs switch-to-buffer-other-frame.

C-x 5 f filename RET

Visit file filename and select its buffer in another frame. This runs find-file-other-frame. Visiting.

C-x 5 d directory RET

Select a Dired buffer for directory directory in another frame. This runs dired-other-frame. Dired.

C-x 5 m

Start composing a mail message in another frame. This runs compose-mail-other-frame. It is the other-frame variant of C-x m. Sending Mail.

C-x 5 .

Find the definition of an identifier in another frame. This runs xref-find-definitions-other-frame, the multiple-frame variant of M-.. Xref.

C-x 5 r filename RET

Visit file filename read-only, and select its buffer in another frame. This runs find-file-read-only-other-frame. Visiting.

C-x 5 5

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. Frame Parameters.