Users of Emacs can customize variables and faces without writing Lisp code, by using the Customize interface. See Easy Customization. This chapter describes how to define customization items that users can interact with through the Customize interface.
Customization items include customizable variables, which are
defined with the
defcustom macro;
customizable faces, which are defined with defface (described
separately in Defining Faces); and customization groups,
defined with
defgroup,
which act as containers for groups of related customization items.