Kritische Faktoren

1. Manual Authority/Weight Given to Site by Google
2. Relevance of Site's Primary Subject Matter to Query
3. Participation in Link Schemes or Actively Selling Links
4. Duplicate Title/Meta Tags on Many Pages
5. Global Link Popularity of Linking Site
6. Quality of the Document Content (as measured algorithmically)
7. Domain Extension of Linking Site (edu, gov, com, ca, co.uk, etc)
8. Server is Often Inaccessible to Bots
9. External Links to Low Quality/Spam Sites
10. TLD Extension of Site (edu, gov, us, ca, com, etc)  

Mehr dazu unter SEOmoz: Ranking Factors Version 2 Released.