Gnus uses the url library to fetch web pages and Emacs/W3 (or those alternatives) to display web pages. Emacs/W3 is documented in its own manual, but there are some things that may be more relevant for Gnus users.
For instance, a common question is how to make Emacs/W3 follow links
browse-url functions (which will call some external web
browser like Netscape). Here's one way:
(eval-after-load "w3" '(progn (fset 'w3-fetch-orig (symbol-function 'w3-fetch)) (defun w3-fetch (&optional url target) (interactive (list (w3-read-url-with-default))) (if (eq major-mode 'gnus-article-mode) (browse-url url) (w3-fetch-orig url target)))))
Put that in your .emacs file, and hitting links in W3-rendered
HTML in the Gnus article buffers will use
follow the link.