Ever wondered how search engines determine the rankings of web pages? Fortune Interactive give us an insight from recent findings of their final research into which metrics influence the major search engines and their rankings.

The final part of this three part study looks at how various on-page and off-page factors affect success across the top three search engines - Google, Yahoo! and MSN, using the key phrase “vacation rentals”. Results found that in-bound link quality was the most important factor on Google, Yahoo! and MSN. This also proved true for the other two studies which looked at “auto insurance” and “laptop”, with in-bound link quantity also proving to be least important among the off-page factors.

With Google, in-bound link quality was 55 times more important than in-bound link quantity, and approximately 2.09 times more important than in-bound link relevance.

The research also found that ranking well across Google, Yahoo! and MSN requires strong performance in the two most important influential factors for each search engine. However, successful link building would require different varying levels of effort for each search engine.