Using the built-in help system of Emacs

Date: 2021-04-21 16:26:50 +08:00Date modified: 2021-07-22 14:25:46 +08:00

GNU Emacs, being a flexible program with a supremely overwhelming number of options to choose from (arguably), has a comprehensive help system.

General help system

help-for-help is a function that gives you a metahelp interface to a number of options such as searching through pattern, logging the last keybindings, display the documentation from a keybinding, describe a language environment, and so on. Most, if not all, of the options presented can be accessed in another way.
apropos, like its similarly named Unix program, searches through the entire symbol list of Emacs (e.g., variable, function) through a pattern.
The series of functions from describe-* has multiple options for various specific things. Among the list of describe functions, I recommend to start with describe-key, describe-function, describe-variable, describe-package, describe-mode, and describe-variable.
Most of the objects (e.g., functions, variables, hooks) in Emacs also require a docstring so you'll have more relevant information at hand.

evil-mode, being inspired from Vim keybindings, adds further into more ways for an instant access to documentation.

evil-lookup, similar to Vim's lookup key (:help K), searches through documentation of the language written on.
evil-goto-definition can sometimes go into the original file where the keyword was defined. It is only useful when the keyword is defined in the project or at least located on the project root.