Panda

Google introduced is new algorithm Panda in 2011. This new algorithm was created to determine if the quality of a page or an article was good or not. It was probably created based on the Caffeine indexation algorithm created to index more content. But which means more content mean more possibility of bad content.

After they released caffeine, more likely they asked Quality Raters ton analyze the quality of the SERP and they likely discovered bad content who were ranking high. The goal is clear, the algorithm define was is a “good content” and a “bad content”