PHP and SEO

I do the majority of my coding with PHP/MySQL and was wondering how this effects SEO. Many of my pages will display information dynamically from a database. Do the bots see the PHP, or the HTML that it outputs?

Also, like any other lazy PHP coder, I tend to use variables in my URL to decrease coding time. For intance, if I have an article.php file which displays an article based on the var aid, will each article be indexed? If I link to these articles on a static page will they be indexed? What other things should I consider when coding in PHP for SEO?

What does your browser see? A bot is a browser.Different engines do different things and different people will tell you different things (b/c they were told by somebody else). Some say Google will support up to one query string variable (eg, ?aid=4, but not ?aid=4&foo=bar), but that it shouldn't be ?id=

It is best to hide your query strings, which can be accomplished on an Apache server with mod_rewrite or the ForceType directive.

if you have some important BLs you will get indexed even if your site is dynamic, however, like davidb2002 said, you should use mod_rewrite