arguments in url question

[grocery_stocker]

The following question stems from the following url

http://xahlee.org/emacs/wrap-url.html

The following function on his web page basically makes a url ouf given
a link.

(defun wrap-url-string (url &optional raw)
  "Make the string into a html link.\n
Example:
http://en.wikipedia.org/wiki/Emacs
becomes
<a href=\"http://en.wikipedia.org/wiki/Emacs\";>Emacs�J</a>.
If the url is a wikipedia link, then the link text
is shortened to its title.
If the optional argument raw is not nil, no shortening will happen."
  (require 'gnus-util)
  (let ((linktext url))
    (setq linktext (gnus-url-unhex-string linktext nil))
    (if (and (not raw) (string-match "wikipedia.org" url))
        (progn
          (setq linktext (concat (car (last (split-string linktext
"/"))) "�J") )
          )
      )
    (concat "<a href=\"" url "\">" linktext "</a>" )
    )
  )

What I don't get is how can a url have optional arguments. I mean
wouldn't something like

“http://yahoo.com/news/3829.php”

just be passed as one argument to the function i this case?