For these posts I'm going to use PHP running on Apache for my examples. It's a popular platform but of course not the only one. These principles apply equally well to any Web technology stack.
I'm also a big fan of URL rewriting. Enabling URL rewriting is as simple as uncommenting mod_rewrite from your Apache config file (typically httpd.conf). Many PHP stacks (eg XAMPP) have this enabled by default. Most if not all hosting providers will have this available on even their cheapest plans.
Or I prefer something like:
My goal is to take well-established best practices and combine them into an easy-to-use PHP-oriented solution so you can easily do things the right way without loss in flexibility or power.