GNU Emacs Manual - Name Help

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## Help by Command or Variable Name

`C-h f` (`describe-function`) reads the name of a Lisp function using the minibuffer, then displays that function's documentation string in a window. Since commands are Lisp functions, you can use this to get the documentation of a command that you know by name. For example,

    C-h f auto-fill-mode RET

displays the documentation of `auto-fill-mode`. This is the only way to get the documentation of a command that is not bound to any key (one which you would normally run using `M-x`).

`C-h f` is also useful for Lisp functions that you are planning to use in a Lisp program. For example, if you have just written the expression `(make-vector len)` and want to check that you are using `make-vector` properly, type `C-h f make-vector `RET``. Because `C-h f` allows all function names, not just command names, you may find that some of your favorite abbreviations that work in `M-x` don't work in `C-h f`. An abbreviation may be unique among command names yet fail to be unique when other function names are allowed.

The function name for `C-h f` to describe has a default which is used if you type `RET` leaving the minibuffer empty. The default is the function called by the innermost Lisp expression in the buffer around point, provided that is a valid, defined Lisp function name. For example, if point is located following the text ``(make-vector (car x)'`, the innermost list containing point is the one that starts with ``(make-vector'`, so the default is to describe the function `make-vector`.

`C-h f` is often useful just to verify that you have the right spelling for the function name. If `C-h f` mentions a name from the buffer as the default, that name must be defined as a Lisp function. If that is all you want to know, just type `C-g` to cancel the `C-h f` command, then go on editing.

`C-h w command `RET`` tells you what keys are bound to command. It prints a list of the keys in the echo area. If it says the command is not on any key, you must use `M-x` to run it. `C-h w` runs the command `where-is`.

`C-h v` (`describe-variable`) is like `C-h f` but describes Lisp variables instead of Lisp functions. Its default is the Lisp symbol around or before point, but only if that is the name of a known Lisp variable. See section Variables.

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