Google Panda and Google Penguin are the most recent algorithms to come out of the Google family to improve the operability of their ranking systems. The algorithms are meant to exclude poor quality websites from higher rankings on the internet. Google Panda was first released in 2011. This was meant as a means of ranking sites with lesser quality content.
Google Penguin is the name of the algorithm update in April of 2012. Since then many webmasters have seen their rankings lower themselves considerably. If a particular site violated the Google Webmasters guidelines then it was punished by lower rankings or excluded altogether. Although this is a rare occurrence, Google has been known to staunchly kick out those sites purposefully implementing black hat techniques.
The violations considered black hat include keyword stuffing, cloaking words, participating in linking schemes, along with the intentional duplication of material on your site and so much more.These will lead directly to drastic lower rankings.
Google has especially designed these to begin punishing those sites participating in over-optimization. This means the most intentional use of search engine optimization techniques. They will usually sense this by determining what is real content and what content is meant to gain higher rankings. Content geared towards increased rankings will be easily penalized content.