65: What are hilit19 and font-lock modes, what is the difference between

     them, and how do I customize them?

  Hilit19 and font-lock are two minor modes that syntactically highlight
  Emacs buffers using colors and fonts of your choosing.  This is
  especially useful when editing code, since strings can be in one face,
  comments a second color, and function definitions a third.  Both packages
  come with Emacs 19.

  Hilit19 is slower than font-lock mode, but is easier to customize and has
  regexps for more major modes.  To invoke hilit19 automatically whenever
  you start Emacs, include the following Lisp forms (stolen from the
  documentation at the top of hilit19.el, which should be in your lisp
  directory) in your .emacs file:

    (cond (window-system
           (setq hilit-mode-enable-list  '(not text-mode)
                 hilit-background-mode   'light
                 hilit-inhibit-hooks     nil
                 hilit-inhibit-rebinding nil)
           (require 'hilit19)))

  Note that hilit-background-mode should be set to 'dark (and not 'light)
  if your Emacs window has a dark background.

  Changing the default hilit19 face specifications requires the use of
  hilit-translate.  See the comments at the top of hilit19.el for some
  examples of how to use hilit-translate, as well as for some basic
  instructions.

  Font-lock is faster than hilit19, but comes with fewer predefined regexps
  and supports fewer major modes.  To enable font-lock for a particular
  mode, you will need to use the hook for that mode.  For example, to turn
  on font-lock mode every time you load an Emacs Lisp file, add the
  following to your .emacs file:

    (add-hook 'emacs-lisp-mode-hook '(lambda () (font-lock-mode 1)))

  Customization of font-lock mode is done by setting the variables
  font-lock-comment-face, font-lock-string-face, font-lock-doc-string-face,
  and font-lock-function-name-face.  You may define new reserved words by
  modifying the variable font-lock-keywords.

  If you want to use hilit19 for some modes and font-lock for others, you
  can use the variable hilit-mode-enable-list.  See the documentation for
  that variable (using M-x describe-variable) for instructions on how to
  set it.

  You might also want to look at Simon Marshall's face-lock package, which
  handles fontification and provides an easier interface to font-lock.  You
  can get face-lock from the Emacs Lisp Archive; see question 87.