URLs are a part of the user interface of every website, be it a full-blown application or just a bunch of static pages. Users sometimes use URLs to navigate, say, by cutting a suffix to "move up a directory". So, we want to present them a clean structured tree. Unfortunately, reality is usually not that nice. We may have some web frameworks stitched together that require their own path names. We may want to hide from the user that she is calling a script. Whatever the reason be, mod_rewrite and mod_redirect are here to help us.

The difference between rewrite and redirect is that a rewrite happens directly in the server, while redirecting a request is done by sending a header to the user telling her where the page really is. This difference is important when deciding whether to rewrite or to redirect. If we have a kind of shortcut or a second domain name and want to direct the user to the "correct" URL, we redirect. Otherwise, we rewrite, for example...