The Google Panda update was first introduced in February 2011 and was designed to stop websites that had poor quality content reaching the top of Google’s search results. The Panda update has been updated multiple times since its first introduction. When Google releases any kind of Panda update many website owners try to back out of any bad quality content techniques they have been employing, unfortunately more often than not they will be caught by a Panda update so the simple rule is make sure your website content is of high quality.
Originally Google were quite vocal about upcoming Panda updates which gave people time to clean up any black hat techniques which they could be picked up on, nowadays however Google don’t give too much away so website owners only find out when they have a decrease in traffic or rankings (when it is too late).
Many people get mixed up with the Panda and Penguin update (What is Penguin) but if you have been hit by a Panda update it is because Google have detected low quality content on your website. If you are using poor quality content as part of your link building techniques on third party website unfortunately you can still be picked up by the Panda update, many people think that you can get away with low quality content on third party website but this isn’t the case.
If you are seeing a big decrease in traffic/leads then there is a good chance you have been picked up by the Panda update, however the only way you can tell for sure that you have been picked up is by logging onto Webmaster Tools. If you have been picked up then you should receive a message from Google informing you of this, if you receive this message then you need to think about cleaning up your content to win back Google’s trust.
There are only going to be more Panda updates in the future, Google only recently released Panda 4.0 back in May 2014. The simple rule to follow here, just make sure your content is of high quality and don’t try to work around it!