There are three basic elements of search engine optimization (seo) - Content, Design, and Meta Tags. All three elements used in conjunction with each other will help to elevate a site's search engine ranking and hopefully increase the traffic to the site.
Content is key in search engine optimization. Search engine spiders need to be able to read what your site is about and if your site lacks content, it will not be ranked highly for the keywords that you are aiming for.
Design is also major factor in a good seo plan because search engine spiders need to get to content, but if your website is filled with graphics and images, the spiders will take that much longer to get to the key ingredient - content.
While the title, keyword, and description meta tags will not make or break your site, they will be instrumental in providing the description that the reader needs to tell them whether or not your site is the one they have been searching for.
Once the search engine spiders have crawled your pages, your site will be ranked based on an algorithm specified by the search engine which tells them how relevant your site is to the keywords that internet users are searching for.
Black Hat search engine optimization (SEO) is usually illegal and unethical tactics to get your site ranked higher. Some of these tactics include doorway pages, invisible links, and keyword stuffing. While these tactics may work initially, when the search engines catch you your site will be banned from the search engine index.