The Drupal SEO grader analyses your website and grades it against SEO best practices. The real value to website owners comes next as the grader detects the site configuration and gives tips and strategies that are specific to that particular Drupal installation. These are not generic suggestions; rather, it's like having a Drupal SEO specialist advising you.
The SEO grader works on five levels
Page Structure evaluates how the site's content is set up. It looks for duplicate content and critical modules that affect a site's structure, such as Page Titles, Google Analytics setup, and Clean URLs.
Crawlability determines how easily the Google spiders can access the content on your site, including the XML Sitemap.
Findability looks at things like the presence of "Like" buttons and overuse of Flash - an SEO killer.
User Experience reports on common needs like content freshness, page speed, and Spam prevention.
Best Practices looks at things that aren't SEO-related but make a site easier to market, such as conversion testing and the presence of usability features.