The company has introduced an update that reduces rankings for low-quality sites and boosts rankings for high-quality sites. Google defines low-quality sites as those that copy content from other sites or sites that are "just not very useful." Conversely, the company recognizes high-quality sites as those that produce original content and information that includes research, thoughtful analysis and so on.
"Google depends on the high-quality content created by wonderful websites around the world, and we do have a responsibility to encourage a healthy web ecosystem. Therefore, it is important for high-quality sites to be rewarded, and that's exactly what this change does." Google hasn't specifically named what "low-quality" sites are affected, but an employee said that "people will get the idea of the types of sites we're talking about."