Google Panda

Google Panda was partially an attempt to deter the creation of content farms and content mills, large sites where keyword stuffing was a significant component of SEO, and where human readers found that much of the data on the site was low-quality content. Google also looked at things like ad-to-content ratios and the greater context of the resources available on one of these websites. For instance, companies that maintain massive encyclopedia or how-to websites with data-poor content were often downgraded in the aftermath of updates like Panda. Over the last several years, Google has instituted dozens of updates like Panda, but Panda and a successor, Penguin in 2012, have been some of the most publicly followed updates in Google's general effort to reward higher-quality business websites.