Google often introduces updates to its search algorithm. These are primarily there to help reduce spammy websites and poor quality websites, in order for good, high quality websites to be seen more easily.
Panda update was first introduced in around 2011. This was a major update which aimed to get rid of poor quality websites, and allow the good websites to climb the rankings more easily.
According to Google, there are a number of factors to look at when deciding if a website is good quality or not:
- The content needs to be written by someone who is considered an expert in that field
- No spammy backlinks pointing to the website at all
- No duplicate content (that is content which is found on other sites or pages in the same wording)
- Trustworthy site for visitors – safe to give out private data such as credit card numbers on
- Good spelling and grammar
- Low bounce rate (how long people spend on the site before moving somewhere else)
Some sites were badly affected by the Panda update. If you have addressed the points above, you should be at a low risk of incurring a Panda penalty.