Your page URL is one of the important factors that you must consider during your SEO process. This factor is not only a factor that has to do with rank for few keywords, this factor (URL) may disallow your page from being indexed by Google!
Search engines feel scary from query parameters since it is easy to get their crawlers stuck crawling few pages with just changing query parameter value dynamically. Google says that a URL that has more than three query parameters may not be indexed. They may index URLs with more query parameters but thats not often. Thus, in your site SEO, you have to avoid query parameters. If you are an online retailer and your product page URL looks like:
/products.php?id=12321&session_id=12121&page=3&name=freezer
You may need to consider restructure your site by rewriting your URLs. I will post later about URL rewriting using Mod_Rewrite. You may consider different URL structures that do not have query parameters like:
/products/Freezer/3
Are you wondering if that will really make difference? Believe me, it makes. Sites that uses query parameters a lot might not get indexed.
Finally, getting rid from query parameters and replacing them with keywords will have real impact on your keywords rank. Given a product, let us say, Microwave in your online retailing site with ID= 32, let us compare two simple URL structures:
1) /products?product_id=32
Versus
2) /products/Microwave
The second URL structure will improve your rank for keywords related to Microwave since search engines will not relate the ID “32″ to your site content.
To summarize, you really need to avoid query parameters. You should try to build keyword rich virtual URL structure for your site. Building a keyword rich URL is not going to be easy, i will write later how to build a router in php to help you to create virtual and keyword rich URLs.