I learned that M-x invokes command execute-extended-command.

Extended commands - GNU Emacs FAQ

What command does C-x invoke?
I looked through the reference but failed to find the answer.

1 Answer 1


In the default configuration, it is not a complete key sequence: it is a prefix key. It is an incomplete specification: it has to be followed by another key (or more than one, if the next key is also a prefix key) before it gets you to a complete key sequence (i.e. one that is bound to a command).

E.g. C-x C-f is bound to the command find-file (by default), C-x f is bound to set-fill-column and C-x n is bound to another prefix key, which could be completed with e.g. another n: C-x n n is bound to the command narrow-to-region. See the section on keymaps in the Emacs Lisp manual for details.

  • To see which key sequences start with C-x, type C-x C-h (this works for any prefix key in place of C-x).
    – MTS
    Commented Feb 7, 2019 at 22:50

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