You may have heard about Google Panda and Penguin updates and penalties, but what do they really mean and why should you care?
Panda and Penguin are both filters and penalties in the Google algorithms that adversely affect the rankings of what Google considers to be low-quality websites. Panda is mostly about low-quality content on a website. Penguin is mostly about webspam, especially low-quality links pointing to a website (a.k.a. inbound links or backlinks). Some sites suffer from downgrading for both practices.
These algorithms are often refreshed (re-run), and updated (changed and re-run). Google also gives each refresh a version number, to make each update easier to identify. It is helpful for people who work in Search Engine Optimization (SEO) to know about specific updates: for example, the Penguin 2.0 update, which took place in May 2013.