What is Google Panda?
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.
Rolled out in Feb 2011 and went global in April 2011 with purpose of lower the websites ranking of low quality & thin websites to return high quality websites rank on its search engine result pages (serps). Websites with high ad-to-content ratios and copied contents are considered as low quality sites. It affects 12 percent of search results.
Google Panda is growing algorithm update and data refreshes for the Google search engine to improve the value of search query results.
Google Panda 4.1 has been made to penalize the websites with poor and thin content. It is based on the feedback from users and webmasters that Google hs been able to identify a few more signals that will help Panda in finding out low content more precisely. So, we can assume that there are high chances for webmasters who were penalized earlier by Google Panda 4.0 to have improved rankings, provided they have followed the guidelines.