URL re-writing with Apache

If you value your website's security, it runs on Apache, and you don't know about URL re-writing you really should check out a really good article about URL re-writing here
There are also many other great reasons to read the article below.

Anyway, basically it shows you how turn this:
http://www.flibbidyjimjams.com/floogle.php?cat=flib&action=cake

into this:

http://www.flibbidyjimjams.com/floogle/flib/cake

and this means that hackers don't even know if you're using ASP or PHP, which is a hurdle straight away. There are also many other fine uses. One pointed out to me by 2kreative is to redirect a .jpg url to a .php - this is useful if you want a dynamically created image for your forum signature, for example, and the forum image posting rules block .php - "haha nice one" I hear you say!!!! yeah well don't be using it for hacking purposes. that's evil.
By the way to quote 2kreative
"you should refer to apaches own documentation to see how in-depth it really is"