well i think URl structure helps u to get more traffic as the accurate path defined may make youe site user friendl.And your URL or the path of the URL dtermined in a proper way can make easy for spiders to crawl the particualr page.
As far as I know search engines don’t really care about you strcture your URL’s that much. However, the URL’s like /prom-dresses are much nicer for humans to read because they are desciptive.
On a page with the URL /prom-dresses I can be quite confident the content will be about prom dresses, where as a page with an URL like /index.php?bla=blah&blabla=blahblah could be about virtually anything.
If you’re looking for a way on how to implement these nicer URL’s you could look in to URL rewriting. Based on your webserver you could either look at mod_rewrite (Apache) or ISAPI Rewrite (IIS).
When they appear in a SERP, it’s obvious to people that the page is relevant if their search terms are contained in the URL
It’s easier for people to type the URL in from scratch or to retype it and find it in the ‘history’
It’s easier for you to manage your site if it’s obvious what each link is
Search engines prefer static URLs for pages that are essentially static, and dynamic URLs (ie, those with ?query=parameter in) for dynamic pages that are generated on the fly.
Search engines may give an infinitessimal boost to pages if search terms appear in the URL, but the other benefits above are more important. What really matters, for static pages, is that you have one consistent canonical URL. If you use queries, make sure that all possible permutations and extraneous parameters are re-written to give the preferred form.