Search engine optimization is the art of creating a website that calls attention to itself by having something worthwhile to show an audience of internet searching users. Calling that attention is a mixed game of making the search engines notice your website and index it to their listings because of its content, structure and keywords (within limits) and of making readers then go on to boost your site’s popularity even further by visiting it frequently, sharing it through other websites or linking to your site through their own websites. In essence, this is what all your efforts are going to be dedicated to; getting it to happen and sustaining it for the long run. Since you want sustainability, the most important SEO tactics are those that create value over the long run.