How Can Search Engines Rank Results? Let Bill Count The Ways

20 Ways Search Engines May Rerank Search Results from Bill Slawski at SEO By The Sea looks at the many ways search engines can or could rank search results after an initial ranking has been determined. Duplicates might be dropped; personal data could influence results; country-specific targeting might happen among other things. Like that? Then you probably want to check out Search Engine Ranking Factors from SEOmoz. Written last year, it covers over 100 factors that search engines might consider to do initial ranking. The main takeaway from me is that all these factors -- pre- and post-ranking -- simply underscore how we are moving further into that world I've written about before, where not everyone will see the same search results for the same query.