RE: What's the meaning of "^A" in emacs?

[Drew Adams <drew.adams@oracle.com>]

> > When you say "input", do you mean to *insert* them as chars into
> > a buffer? If so, just hit C-q first.  But I don't think you
> > should do this too often (?).
> 
> Yes, why would someone use this? The only thing that I use is the
> "form feed" (^L) to divide sections in plain text documents and
> then be able to use C-x [ and C-x ] to move between pages.
> 
> Does someone know of any other "control character" use?

It is common to use `C-j' when you interactively enter a regexp
that contains a newline char (Control J).  This is because
(vanilla) Emacs binds `C-j' in the minibuffer to a command other
than self-insertion.

(FWIW - That's a misfeature, but hey, it took a couple decades to
get `SPC' to insert in the minibuffer, and it still does so only
for file-name input.  It will be another decade or several before
newline and `?' earn their rightful place as self-inserters.)

Similarly, if you want to query-replace something that contains
carriage-return (`C-m') chars, then you will use `C-q C-m' (aka
`C-q RET') to pass the `C-m' char to the query string.

Emacs is very general.  The ASCII control chars are, well, just
chars.  You can use them wherever you want, including in strings.
Chars,in strings or otherwise, are not used only for display.