Do I understand URL Rewriting right?

I dont need to know now how it's done, I just need to ensure it's possible.
Dont know much about url rewriting, but from what I understand, one can do the following.

I can create my directory structure of the website any way that suits my specific needs.
However, I might end up with urls like :
www.mysite.com/main/home.php
www.mysite.com/tuturials/php/oop/classes.php

I can cause the above url's to "show" as:
www.mysite.com
www.mysite.com/classes
or whatever I might fancy

Am I right, and if so is there anything that I need to make sure of in advance?
I'll be hosting on WAMP (with win2k3 server)

cheers

You're right.