Emacs provides a wide variety of help commands, all accessible
through the prefix key C-h (or, equivalently, the function key
F1). These help commands are described in the following
sections. You can also type C-h C-h to view a list of help
commands (help-for-help). You can scroll the list with
SPC and DEL, then type the help command you want. To
cancel, type C-g.
Many help commands display their information in a special help buffer. In this buffer, you can type SPC and DEL to scroll and type RET to follow hyperlinks. See Help Mode Commands.
By default, help commands display the help buffer in a separate
window without selecting that window. The variable
help-window-select controls this: its default value is
nil; if it’s customized to the value t, the help window
is unconditionally selected by help commands, and if its value is
other, the help window is selected only if there are more than
two windows on the selected frame.
Conversely, many commands in the ‘*Help*’ buffer will pop up a
new window to display the results. For instance, clicking on the link
to show the source code, or using the i command to display the
manual entry, will (by default) pop up a new window. If
help-window-keep-selected is changed to non-nil, the
window displaying the ‘*Help*’ buffer will be reused instead.
If you are looking for a certain feature, but don’t know what it is called or where to look, we recommend three methods. First, try apropos commands, then try searching the manual index, then look in the FAQ and the package keywords, and finally try listing external packages.
This searches for commands whose names match the argument topics. The argument can be a keyword, a list of keywords separated by whitespace, or a regular expression (see Syntax of Regular Expressions). See Apropos.
Similar, but searches the text of the documentation strings rather than the names of commands and functions.
This searches for topic in the indices of the Emacs Info manual, displaying the first match found. Press , to see subsequent matches. You can use a regular expression as topic.
Similar, but searches the text of the manual rather than the indices.
This displays the Emacs FAQ, using Info.
This displays the available Emacs packages based on keywords. See Keyword Search for Packages.
This displays a list of external packages. See Emacs Lisp Packages.
C-h or F1 mean “help” in various other contexts as well. For instance, you can type them after a prefix key to view a list of the keys that can follow the prefix key. (You can also use ? in this context. A few prefix keys don’t support C-h or ? in this way, because they define other meanings for those inputs, but they all support F1.)
Here is a summary of help commands for accessing the built-in documentation. Most of these are described in more detail in the following sections.
Display a list of commands whose names match topics
(apropos-command). See Apropos.
Display all active key bindings; minor mode bindings first, then those
of the major mode, then global bindings (describe-bindings).
See Other Help Commands.
Toggle display of a window showing popular commands and their key bindings. See Other Help Commands.
Show the name of the command that the key sequence key is bound
to (describe-key-briefly). Here c stands for
“character”. For more extensive information on key, use
C-h k. See Documentation for a Key.
Display the commands and variables whose documentation matches
topics (apropos-documentation). See Apropos.
Display the *Messages* buffer
(view-echo-area-messages). See Other Help Commands.
Display documentation on the Lisp function named function
(describe-function). Since commands are Lisp functions, this
works for commands too, but you can also use C-h x. See Help by Command or Variable Name.
Display the HELLO file, which shows examples of various character sets.
Run Info, the GNU documentation browser (info). The Emacs
manual is available in Info. See Other Help Commands.
Display the name and documentation of the command that key runs
(describe-key). See Documentation for a Key.
Display a description of your last 300 keystrokes
(view-lossage). See Other Help Commands.
Display documentation of the current major mode and minor modes
(describe-mode). See Other Help Commands.
Display news of recent Emacs changes (view-emacs-news).
See Help Files.
Display documentation of the Lisp symbol named symbol
(describe-symbol). This will show the documentation of all
kinds of symbols: functions, variables, and faces. See Help by Command or Variable Name.
Find packages by topic keyword (finder-by-keyword).
See Keyword Search for Packages. This lists packages using a package menu
buffer. See Emacs Lisp Packages.
Display documentation about the specified package
(describe-package). See Keyword Search for Packages.
Display the Emacs manual in Info (info-emacs-manual).
Display the contents of the current syntax table
(describe-syntax). See Other Help Commands. The syntax table says
which characters are opening delimiters, which are parts of words, and
so on. See Syntax Tables in The Emacs Lisp
Reference Manual, for details.
Enter the Emacs interactive tutorial (help-with-tutorial).
Display the documentation of the Lisp variable var
(describe-variable). See Help by Command or Variable Name.
Show which keys run the command named command (where-is).
See Documentation for a Key.
Display documentation on the named command
(describe-command). See Help by Command or Variable Name.
Describe the coding system coding
(describe-coding-system). See Coding Systems.
Describe the coding systems currently in use.
Enter Info and go to the node that documents the Emacs command
command (Info-goto-emacs-command-node). See Help by Command or Variable Name.
Describe the input method method (describe-input-method).
See Selecting an Input Method.
Enter Info and go to the node that documents the key sequence
key (Info-goto-emacs-key-command-node). See Documentation for a Key.
Display information on the character sets, coding systems, and input
methods used in language environment language-env
(describe-language-environment). See Language Environments.
Display the Info documentation on symbol symbol according to the
programming language you are editing (info-lookup-symbol).
See Other Help Commands.
Display the help message for a special text area, if point is in one
(display-local-help). (These include, for example, links in
*Help* buffers.) See Help on Active Text and Tooltips. If you invoke
this command with a prefix argument, C-u C-h ., and point is on
a button or a widget, this command will pop a new buffer that
describes that button/widget.
The help commands to get information about a key sequence are
C-h c (describe-key-briefly) and C-h k
(describe-key).
C-h c key displays in the echo area the name of the command that key is bound to. For example, C-h c C-f displays ‘forward-char’.
C-h k key is similar but gives more information: it displays a help buffer containing the command’s documentation string, which describes exactly what the command does.
C-h K key displays the section of the Emacs manual that describes the command corresponding to key.
C-h c, C-h k and C-h K work for any sort of key sequences, including function keys, menus, and mouse events (except that C-h c ignores mouse movement events). For instance, after C-h k you can select a menu item from the menu bar, to view the documentation string of the command it runs.
C-h w command RET lists the keys that are bound to
command. It displays the list in the echo area. If it says the
command is not on any key, that means you must use M-x to run
it. C-h w runs the command where-is.
Some modes in Emacs use various buttons (see Buttons in The
Emacs Lisp Reference Manual) and widgets
(see Introduction in Emacs Widgets) that can be clicked to
perform some action. To find out what function is ultimately invoked
by these buttons, Emacs provides the button-describe and
widget-describe commands, that should be run with point over
the button.
M-x which-key is a global minor mode which helps in discovering keymaps. It displays keybindings following your currently entered incomplete command (prefix), in a popup.
C-h x command RET (describe-command)
displays the documentation of the named command, in a
window. For example,
C-h x auto-fill-mode RET
displays the documentation of auto-fill-mode. This is how you
would 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 function RET (describe-function)
displays the documentation of Lisp function. This command is
intended for Lisp functions that you 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.
Additionally, since all commands are Lisp functions, you can also use
this command to view the documentation of any command.
If you type C-h f RET, it describes the function called
by the innermost Lisp expression in the buffer around point,
provided that function name is a valid, defined Lisp function.
(That name appears as the default while you enter the argument.) 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 C-h f RET describes the
function make-vector.
C-h f is also useful just to verify that you spelled a function name correctly. If the minibuffer prompt for C-h f shows the function name from the buffer as the default, it means that name is defined as a Lisp function. Type C-g to cancel the C-h f command if you don’t really want to view the documentation.
The function’s documentation displayed by describe-function
includes more than just the documentation string and the signature of
the function. It also shows auxiliary information such as its type, the
file where it was defined, whether it has been declared obsolete, and
yet further information is often reachable by clicking or typing
RET on emphasized parts of the text.
The function type, if known, is expressed with a function type specifier (see Type Specifiers in The Emacs Lisp Reference Manual), it will be specified if the type was manually declared by a Lisp program or inferred by the compiler. Note that function type inference works only when native compilation is enabled (see native compilation in The Emacs Lisp Reference Manual).
If you request help for an autoloaded function whose autoload
form (see Autoload in The Emacs Lisp Reference Manual)
doesn’t provide a doc string, the *Help* buffer won’t have any
doc string to display. In that case, if
help-enable-symbol-autoload is non-nil, Emacs will try
to load the file in which the function is defined to see whether
there’s a doc string there.
You can get an overview of functions relevant for a particular topic
by using the M-x shortdoc command. This will prompt you for an
area of interest, e.g., string, and pop you to a buffer where
many of the functions relevant for handling strings are listed.
You can also request that documentation of functions and commands shown in *Help* buffers popped by C-h f includes examples of their use. To that end, add the following to your initialization file (see The Emacs Initialization File):
(add-hook 'help-fns-describe-function-functions
#'shortdoc-help-fns-examples-function)
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, if that is the name of a
defined Lisp variable. See Variables.
Help buffers that describe Emacs variables and functions normally have hyperlinks to the corresponding source code, if you have the source files installed (see Hyperlinking and Web Navigation Features).
To find a command’s documentation in a manual, use C-h F
(Info-goto-emacs-command-node). This knows about various
manuals, not just the Emacs manual, and finds the right one.
C-h o (describe-symbol) is like C-h f and
C-h v, but it describes any symbol, be it a function, a
variable, or a face. If the symbol has more than one definition, like
it has both definition as a function and as a variable, this command
will show the documentation of all of them, one after the other.
C-h 4 s (help-find-source) switch to a buffer visiting
the source definition of what is being described in the help buffer.
If the completions-detailed user option is non-nil,
some commands provide details about the possible values when
displaying completions. For instance, C-h o TAB will then
include the first line of the doc string, and will also say whether
each symbol is a function or a variable (and so on). Which details
are included varies depending on the command used.
The apropos commands answer questions like, “What are the commands for working with files?” More precisely, you specify your query as an apropos pattern, which is either a word, a list of words separated by whitespace, or a regular expression.
Each of the following apropos commands reads an apropos pattern in the minibuffer, searches for items that match the pattern, and displays the results in a different window.
Search for commands (apropos-command). With a prefix argument,
search for noninteractive functions too.
Search for functions and variables. Both interactive functions (commands) and noninteractive functions can be found by this.
Search for user-customizable variables. With a prefix argument, search for non-customizable variables too.
Search for variables. With a prefix argument, search for customizable variables only.
Search for buffer-local variables.
Search for variables whose values match the specified pattern. With a prefix argument, search also for functions with definitions matching the pattern, and Lisp symbols with properties matching the pattern.
Search for buffer-local variables whose values match the specified pattern.
Search for functions and variables whose documentation strings match
the specified pattern (apropos-documentation).
The simplest kind of apropos pattern is one word. Anything
containing that word matches the pattern. Thus, to find commands that
work on files, type C-h a file RET. This displays a list
of all command names that contain ‘file’, including
copy-file, find-file, and so on. Each command name
comes with a brief description and a list of keys you can currently
invoke it with. In our example, it would say that you can invoke
find-file by typing C-x C-f.
By default, the window showing the apropos buffer with the results
of the query is not selected, but you can cause it to be selected by
customizing the variable help-window-select to any
non-nil value.
For more information about a function definition, variable or symbol property listed in an apropos buffer, you can click on it with mouse-1 or mouse-2, or move there and type RET.
When you specify more than one word in the apropos pattern, a name
must contain at least two of the words in order to match. Thus, if
you are looking for commands to kill a chunk of text before point, you
could try C-h a kill back backward behind before RET. The
real command name kill-backward will match that; if there were
a command kill-text-before, it would also match, since it
contains two of the specified words.
For even greater flexibility, you can specify a regular expression (see Syntax of Regular Expressions). An apropos pattern is interpreted as a regular expression if it contains any of the regular expression special characters, ‘^$*+?.\[’.
Following the conventions for naming Emacs commands, here are some words that you’ll find useful in apropos patterns. By using them in C-h a, you will also get a feel for the naming conventions.
char, line, word, sentence, paragraph, region, page, sexp, list, defun, rect, buffer, frame, window, face, file, dir, register, mode, beginning, end, forward, backward, next, previous, up, down, search, goto, kill, delete, mark, insert, yank, fill, indent, case, change, set, what, list, find, view, describe, default.
If the variable apropos-do-all is non-nil, most
apropos commands behave as if they had been given a prefix argument.
There is one exception: apropos-variable without a prefix
argument will always search for all variables, no matter what the
value of apropos-do-all is.
By default, all apropos commands except apropos-documentation
list their results in alphabetical order. If the variable
apropos-sort-by-scores is non-nil, these commands
instead try to guess the relevance of each result, and display the
most relevant ones first. The apropos-documentation command
lists its results in order of relevance by default; to list them in
alphabetical order, change the variable
apropos-documentation-sort-by-scores to nil.
Help buffers have Help mode as their major mode. Help mode provides the same commands as View mode (see View Mode); for instance, SPC scrolls forward, and DEL or S-SPC scrolls backward. It also provides a few special commands:
Follow a cross-reference at point (help-follow).
Move point forward to the next hyperlink (forward-button).
Move point back to the previous hyperlink (backward-button).
Follow a hyperlink that you click on.
Move forward and back between pages in the Help buffer.
Show all documentation about the symbol at point
(help-follow-symbol).
Go forward in history of help commands (help-go-forward).
Go back in history of help commands (help-go-back).
View the source of the current help topic (if any)
(help-view-source).
Look up the current topic in the manual(s) (help-goto-info).
Look up the current topic in the Emacs Lisp manual
(help-goto-lispref-info).
Customize the variable or the face (help-customize).
When a function name, variable name, or face name (see Text Faces)
appears in the documentation in the help buffer, it is normally an
underlined hyperlink. To view the associated documentation,
move point there and type RET (help-follow), or click on
the hyperlink with mouse-1 or mouse-2. Doing so replaces
the contents of the help buffer; to retrace your steps, type C-c
C-b or l (help-go-back). While retracing your steps,
you can go forward by using C-c C-f or r
(help-go-forward).
To move between hyperlinks in a help buffer, use TAB
(forward-button) to move forward to the next hyperlink and
S-TAB (backward-button) to move back to the
previous hyperlink. These commands act cyclically; for instance,
typing TAB at the last hyperlink moves back to the first
hyperlink.
By default, many links in the help buffer are displayed surrounded
by quote characters. If the help-clean-buttons user option is
non-nil, these quote characters are removed from the buffer.
Help buffers produced by some Help commands (like C-h b, which
shows a long list of key bindings) are divided into pages by the
‘^L’ character. In such buffers, the n
(help-goto-next-page) command will take you to the next start
of page, and the p (help-goto-previous-page) command will
take you to the previous start of page. This way you can quickly
navigate between the different kinds of documentation in a help
buffer.
A help buffer can also contain hyperlinks to Info manuals, source
code definitions, and URLs (web pages). The first two are opened in
Emacs, and the third using a web browser via the browse-url
command (see Following URLs).
To view all documentation about any symbol in the text, move point
to the symbol and type C-c C-c (help-follow-symbol).
This shows the documentation for all the meanings of the symbol—as a
variable, as a function, and/or as a face.
Most optional features in Emacs are grouped into packages. Emacs contains several hundred built-in packages, and more can be installed over the network (see Emacs Lisp Packages).
To make it easier to find packages related to a topic, most packages
are associated with one or more keywords based on what they do.
Type C-h p (finder-by-keyword) to bring up a list of
package keywords, together with a description of what the keywords
mean. To view a list of packages for a given keyword, type RET
on that line; this displays the list of packages in a Package Menu
buffer (see The Package Menu Buffer).
C-h P (describe-package) prompts for the name of a
package (see Emacs Lisp Packages), and displays a help buffer describing the
attributes of the package and the features that it implements. The
buffer lists the keywords that relate to the package in the form of
buttons. Click on a button with mouse-1 or mouse-2 to see
the list of other packages related to that keyword.
For information on a specific language environment (see Language Environments), type C-h L
(describe-language-environment). This displays a help buffer
describing the languages supported by the language environment, and
listing the associated character sets, coding systems, and input
methods, as well as some sample text for that language environment.
The command C-h h (view-hello-file) displays the file
etc/HELLO, which demonstrates various character sets by showing
how to say “hello” in many languages.
The command C-h I (describe-input-method) describes an
input method—either a specified input method, or by default the
input method currently in use. See Input Methods.
The command C-h C (describe-coding-system) describes
coding systems—either a specified coding system, or the ones
currently in use. See Coding Systems.
C-h i (info) runs the Info program, which browses
structured documentation files. C-h 4 i
(info-other-window) does the same, but shows the Info buffer in
another window. The entire Emacs manual is available within Info,
along with many other manuals for the GNU system. Type h after
entering Info to run a tutorial on using Info.
With a numeric argument n, C-h i selects the Info buffer ‘*info*<n>’. This is useful if you want to browse multiple Info manuals simultaneously. If you specify just C-u as the prefix argument, C-h i prompts for the name of a documentation file, so you can browse a file which doesn’t have an entry in the top-level Info menu.
The help commands C-h F function RET and C-h K key, described above, enter Info and go straight to the documentation of function or key.
When editing a program, if you have an Info version of the manual
for the programming language, you can use C-h S
(info-lookup-symbol) to find an entry for a symbol (keyword,
function or variable) in the proper manual. The details of how this
command works depend on the major mode.
If something surprising happens, and you are not sure what you typed,
use C-h l (view-lossage). C-h l displays your last
input keystrokes and the commands they invoked. By default, Emacs
stores the last 300 keystrokes; if you wish, you can change this number with
the command lossage-size.
If you see commands that you are not familiar with, use
C-h k, or press RET or click on them to find out what they do.
By default, once the lossage buffer is displayed, it will not show the
keystroke and commands you will type after displaying it. But if you
set the variable view-lossage-auto-refresh to the value t,
the lossage buffer will be continuously refreshed as you type further
commands. Alternatively, you can invoke view-lossage with a
prefix argument, as in C-u C-h l, to display the lossage buffer
and have it auto-refresh thereafter.
To review recent echo area messages, use C-h e
(view-echo-area-messages). This displays the buffer
*Messages*, where those messages are kept.
Each Emacs major mode typically redefines a few keys and makes other
changes in how editing works. C-h m (describe-mode)
displays documentation on the current major mode, which normally
describes the commands and features that are changed in this mode, and
also its key bindings.
C-h b (describe-bindings) and C-h s
(describe-syntax) show other information about the current
environment within Emacs. C-h b displays a list of all the key
bindings now in effect: first the local bindings of the current minor
modes, then the local bindings defined by the current major mode, and
finally the global bindings (see Customizing Key Bindings). C-h s
displays the contents of the syntax table, with explanations of each
character’s syntax (see Syntax Tables in The
Emacs Lisp Reference Manual).
C-h C-q (help-quick-toggle) toggles on and off the
display of a buffer showing the most popular Emacs commands and their
respective key bindings (a.k.a. “cheat sheet”). The contents of
that buffer are created by the command help-quick. Each key
binding shown in this buffer is a button: click on it with
mouse-1 or mouse-2 to show the documentation of the
command bound to that key sequence.
You can get a list of subcommands for a particular prefix key by
typing C-h, ?, or F1
(describe-prefix-bindings) after the prefix key. (There are a
few prefix keys for which not all of these keys work—those that
provide their own bindings for that key. One of these prefix keys
is ESC, because ESC C-h and ESC ? are
actually C-M-h (mark-defun) and M-?
(xref-find-references), respectively. However,
ESC F1 works fine.)
Finally, M-x describe-keymap prompts for the name of a keymap, with completion, and displays a listing of all key bindings in that keymap.
Apart from the built-in documentation and manuals, Emacs contains several other files describing topics like copying conditions, release notes, instructions for debugging and reporting bugs, and so forth. You can use the following commands to view these files. Apart from C-h g, they all have the form C-h C-char.
Display the rules under which you can copy and redistribute Emacs
(describe-copying).
Display help for debugging Emacs (view-emacs-debugging).
Display information about where to get external packages
(view-external-packages).
Display the Emacs frequently-answered-questions list (view-emacs-FAQ).
Visit the page with information about the GNU
Project (describe-gnu-project).
Display information about ordering printed copies of Emacs manuals
(view-order-manuals).
Display the news, which lists the new features in this
version of Emacs (view-emacs-news).
Display how to order or download the latest version of
Emacs and other GNU software (describe-distribution).
Display the list of known Emacs problems, sometimes with suggested
workarounds (view-emacs-problems).
Display the Emacs to-do list (view-emacs-todo).
Display the full details on the complete absence of warranty for GNU
Emacs (describe-no-warranty).
In Emacs, stretches of active text (text that does something special in response to mouse clicks or RET) often have associated help text. This includes hyperlinks in Emacs buffers, as well as parts of the mode line. On graphical displays, as well as some text terminals which support mouse tracking, moving the mouse over the active text displays the help text as a tooltip. See Tooltips.
On terminals that don’t support mouse-tracking, you can display the
help text for active buffer text at point by typing C-h .
(display-local-help). This shows the help text in the echo
area. To display help text automatically whenever it is available at
point, set the variable help-at-pt-display-when-idle to
t. If you use Eldoc, set the variable eldoc-help-at-pt
to t instead.