Google Panda - The Night Mare of Bloggers

Google Panda refers to the changes introduced in 2011 to the search algorithm used by Google to improve Internet search results.
The change aims to lower the rank of "low-quality sites" in search results and return high-quality sites to Google's users.CNET reported a surge in the rankings of news websites and social Networking sites, and a drop in rankings for advertising sites.This change reportedly affected the rankings of almost 12 percent of all search results.
Google Panda was built through an algorithm update that used artificial intelligence in a more sophisticated and scalable way than previously possible. Human quality testers rated thousands of websites based on measures of quality, including design, trustworthiness, speed and whether or not they would return to the website.
Google's new Panda machine-learning algorithm, made possible by and named after engineer Navneet Panda, was then used to look for similarities between websites people found to be high quality and low quality.
Many new ranking factors have been introduced to the Google algorithm as a result, while older ranking factors like PageRank have been downgraded in importance.