What is Google Panda?

Google Panda is a change to Google's search results ranking algorithm that was released 2/2011. The change aimed to lower the rank of "low-quality sites" or "thin sites", and return higher-quality sites near the top of the search results. This algorithm will based on rating about speed, quality of content, design, site structure... Google Panda was released to replace Google Cafein, because Google Cafein has too many flaws. The main purpose of Google Panda is erase duplicate content, copy content, low quality website...

Google Panda and its changing.
With the developing of Internet and Marketing Online, there are more and more website was created. By using many web framework open source like wordpress, joomla... people can create many websites. Many website was created to advert, spam, get fake traffic, spam content... We often call these websites are "spam website, trash website" . And there are many website copy content from other website and post on their website. They have violate about author's copyright rules. Number of these websites are increasing. They can use some auto tools to get articles from other website, some auto post contents tools... So many high-quality was push down at the bottom of search results. Because rank for website based on number of articles, density keywords, number of links... When users search, these website will at the top of search results. But quality of these websites are low, so users don't like this. Google think that the time to resolve and changing was come. So they was announce about new algorithm to resolve these problems. With Google Panda they will eliminate all website has duplicate content, spam website, low quality that has bad structure... All quality website will be at the top of search results.

How Google Panda rate website with Google Panda.
Google Panda will evaluate websites base on 4 criteria.
1. Time visit.
If you content is good and useful, visitors will stay on your website longer. So time visitors stay on your website will be used to evaluate your website quality. And these websites will be Google push up to top of search result.

2. Bounce Rate.
If your website usually has visitors, it will be Google evaluate that a quality website. If has a big amount of frequency visitors, website will have a high bounce rate.

3. Visitors come back rate.
Quality content with time visit long and high bounce rate are very good. But don't have many visitors come back site isn't good. So Google also evaluate website base on number of visitors come back.

4. Social Network.
With developing quickly of social network with billion people. These people will share anything that they think it is useful for their friends. So if your website was shared on many big social network like facebook, google plus, twitter... Google will rate that your website content is quality.

They are four brief main criteria of Google Panda algorithm. In detail we can have 23 criteria to evaluate websites:

• Would you trust the information presented in this article?
• Is this article written by an expert or enthusiast who knows the topic well, or is it more shallow in nature?
• Does the site have duplicate, overlapping, or redundant articles on the same or similar topics with slightly different keyword variations?
• Would you be comfortable giving your credit card information to this site?
• Does this article have spelling, stylistic, or factual errors?
• Are the topics driven by genuine interests of readers of the site, or does the site generate content by attempting to guess what might rank well in search engines?

• Does the article provide original content or information, original reporting, original research, or original analysis?
• Does the page provide substantial value when compared to other pages in search results?
• How much quality control is done on content?
• Does the article describe both sides of a story?
• Is the site a recognized authority on its topic?
• Is the content mass-produced by or outsourced to a large number of creators, or spread across a large network of sites, so that individual pages or sites don’t get as much attention or care?
• Was the article edited well, or does it appear sloppy or hastily produced?
• For a health related query, would you trust information from this site?
• Would you recognize this site as an authoritative source when mentioned by name?
• Does this article provide a complete or comprehensive description of the topic?
• Does this article contain insightful analysis or interesting information that is beyond obvious?
• Is this the sort of page you’d want to bookmark, share with a friend, or recommend?
• Does this article have an excessive amount of ads that distract from or interfere with the main content?
• Would you expect to see this article in a printed magazine, encyclopedia or book?
• Are the articles short, unsubstantial, or otherwise lacking in helpful specifics?
• Are the pages produced with great care and attention to detail vs. less attention to detail?
• Would users complain when they see pages from this site?

When Google announce about releasing Google Panda algorithm, there are hundred of thousands complaint about rank reducing of their.But Google said that they only evaluate website base on 23 criteria of Google Panda.
So to get a higher rank in Google search engine, you should do follow Google Panda criteria.