gistfile1.txt

C-x C-f runs the command ido-find-file, which is an interactive autoloaded
compiled Lisp function in ‘ido.el’.

It is bound to <open>, C-x C-f, <menu-bar> <file> <new-file>.

(ido-find-file)

Edit file with name obtained via minibuffer.
The file is displayed according to ‘ido-default-file-method’ -- the
default is to show it in the same window, unless it is already visible
in another frame.

The file name is selected interactively by typing a substring.  As you
type in a string, all of the filenames matching the string are displayed
if substring-matching is used (default).  Look at ‘ido-enable-prefix’ and
‘ido-toggle-prefix’.  When you have found the filename you want, it can
then be selected.  As you type, most keys have their normal keybindings,
except for the following: 

RET	Select the file at the front of the list of matches.
	If the list is empty, possibly prompt to create new file.

C-j	Use the current input string verbatim.

C-s	Put the first element at the end of the list.
C-r	Put the last element at the start of the list.
TAB	Complete a common suffix to the current string that matches
	all files.  If there is only one match, select that file.
	If there is no common suffix, show a list of all matching files
	in a separate window.
C-d	Open the specified directory in Dired mode.
C-e	Edit input string (including directory).
M-p	Go to previous directory in work directory history.
M-n	Go to next directory in work directory history.
M-s	Search for file in the work directory history.
M-k	Remove current directory from the work directory history.
M-o	Cycle to previous file in work file history.
C-M-o	Cycle to next file in work file history.
M-f	Prompt for a file and use find to locate it.
M-d	Prompt for a directory and use find to locate it.
M-m	Prompt for a directory to create in current directory.
C-x C-f	Fallback to non-Ido version of current command.
C-t	Toggle regexp searching.
C-p	Toggle between substring and prefix matching.
C-c	Toggle case-sensitive searching of file names.
M-l	Toggle literal reading of this file.
?	Show list of matching files in separate window.
C-a	Toggle ignoring files listed in ‘ido-ignore-files’.