Info

Info is the hypertext help/reference browser in GNU Emacs. You invoke its top level with [C-h i] (or M-x info).

M-x info-apropos

Don't know where to go in Info? Try this command. For example, try M-x info-apropos RET compile RET to get some overview of compilation support in Emacs.

[C-h r] (or M-x info-emacs-manual)

Learn how to use GNU Emacs. Very detailed.

[C-h i] (or M-x info)

See the Info manuals of all packages that come with your GNU Emacs, and of any third-party packages and external programs whose info files Info finds in its search path.

[i]

While in an Info buffer, jump to some topic of interest. To learn about regular expressions try [C-h r] and [i regular TAB].

[I]

Same as [i] but gives you a list of links.

[L]

Try this if you are lost and overwhelmed by the amount of information available and you want to reflect on where all you went and how you got lost.

[C-u C-h i]

You have installed a Third party package. It includes (or you have created with makeinfo) an info file. This command allows you to browse this info file. To make the info file's contents permanently available in Info's top level, you can add the info file's containing directory to Info's search path using M-x customize-variable RET Info-directory-list, or by editing the INFOPATH environment variable and re-starting Emacs.