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 an apropos command, 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, or a regular expression (see Syntax of Regular Expressions). See Apropos.
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.)