The ultimate goal of SEO ids to increase the site's usability so that you can bring the right people in from the search engines. The purpose of your site should be clearly defined so that you can make sure your site achienes that purpose. When search engine visitors see that your site meets their expectations after they find you on a web search, this means your usabilioty is solid. If visitors are dissapointed, the site has missed its mark. The goal is to follow the best strategies possible for ranking in the search engines, and to do this you need to understand hjow they want things done.