The Panda update was a huge Google algorithm update that put a focus on quality content. Prior to the update web content publishers would post the same article or blog post on many sites. The thought was that the more frequently it was “out there”, the more likely it would be that the search engine spiders would find it and rank it. Panda cracked down on this practice and sites that allowed duplicated content (many of the article submission sites) were sent way down and nearly disappeared from the results.