What is Google Panda Update? What is the cause of the Google Panda Update?
 

Google's Panda Update is a search filter introduced in February 2011 meant to stop sites with poor quality content from working their way into Google's top search results. Panda is updated from time-to-time. When this happens, sites previously hit may escape, if they've made the right changes.

Google Panda is a major change to Google's search results ranking algorithm that was first released in February 2011. The change aimed to lower the rank of "low-quality sites" or "thin sites", in particular "content farms", and return higher-quality sites near the top of the search results.