Goggle’s latest algorithmic change is aimed at content farms and other low quality sites. To be clear, Google did not specifically say content farms were the target of the update. In fact, Matt Cutts – head of Google’s Spam Fighting Team said, “I think people will get the idea of the types of sites we’re talking about.”
These sites only goal is to attract a large amount of search traffic using popular search terms, but the content is mainly useless. Google say about 12% of US search results (11.8% to be more exact) will be impacted.