There are "over 200 SEO factors" that Google uses to rank pages in the Google search results (SERPs). What are the search engine optimization rules?
Here is the speculation - educated guesses by SEO webmasters on top webmaster forums. Should you wish to achieve a high ranking, the various confirmed and suspected Google Search Engine Optimization (SEO) Rules are listed below.

Google Ranking Factors - SEO Checklist

They are talking about Panda, etc Anyway it is interesting to keep an eye on that.