Look at this Bad example URL: www.example.com/cgi-bin/shop.php?cmd=product&category=vehicles&product=bus
Is your PHP website's dynamic URL too zigzag to remember, just like the example you saw above? Oops!, this a threat for SEO ranking. Google always keep this websites in backbench.
Hire me to set a system that will convert dynamic URLs into search engine friendly vanity URLs automatically. Static URLs typically rank better in search engines than long complex dynamic URLs with lots of parameters, they are easier to index in the first place and they're also friendlier looking to the end user.
Possible Vanity URLs (you will choose any of these):