Documents which generally are trusted less and rank lower than documents in the main search index.
Some search engines, such as Google, have multiple indicies. Documents which are not well trusted due to any of the following conditions:
- limited link authority relative to the number of pages on the site
- duplicate content or near duplication
- exceptionally complex URLs
Documents in the supplemental results are crawled less frequently than documents in the main index. Since documents in the supplemental results are typically considered to be trusted less than documents in the regular results, those pages probably carry less weight when they vote for other pages by linking at them.
You can find document’s on this site that are in Google’s supplemental results by searching for site:seobook.com *** -view:randomstring