In Chapter 9, we discuss how search engines choose the #1 organic search result–it uses the ranking algorithm. Google and the other search engines each use different ranking algorithms with different weights for different ranking factors. Ranking algorithms are trade secrets for each search engine, so no one outside their respective companies actually knows the actual factors for their algorithms.
But that doesn’t stop us from speculation. Here’s an infographic for some 200 possible ranking factors.
Perhaps the most intelligent speculation come from an annual survey of professional SEOs conducted by Moz. Each year the publish the results of the survey, which can help you know the kinds of changes that seem to be appearing in organic search ranking factors. A separate survey for local search ranking factors is equally awaited each year.