Naming your urls using your keyword phrases help immensely. They are another way of telling search engines what this page's content is going to be about. They also tell searchers what they can expect to find related to it. Search engines figure that if a page contains an url called "fashion-diva-Donatella-purple-shoes-in-Cork-window, the page will about shoes, fashion, maybe even a bit about Donatella Versace and also be relevant to Cork City or Cork County. Web searchers typing in any of those things may find your website page because of that. Use hyphens to separate words (-) not underscores (_). Google sees hyphens as word separators and underscores as word joiners so lovely-url-name becomes lovely url name where lousy_url_name becomes lousyurlname.