The Penguin Update was designed to battle spam link tactics and monitor the quality of links to a website. The update was originally released back in april 2012 and it immediately caused major ripples in the digital industry. Sites who weren't playing by the rules were suddenly missing from search results, many of them receiving manual actions.
Later updates were released over the past few years, and every time Penguin is released there are significant changes to the way the search results look. But for the most part it's a positive update for websites that are doing marketing the proper way and a major detractor for those trying to cheat the system.
What's Different With Penguin 4.0?
Penguin 4.0 is rumored to be a real time update to the algorithm. This means that the Penguin portion of the algorithm will always be "on" and updating. This is huge news for the digital marketing community since there's still a prevalence of spammy tactics taking place. In fact, even though Google claims that black-hat tactics do not work, there's lots of evidence that the contrary is true. But in Google's defense, they are making it much more difficult for black-hat marketers to succeed.
With Penguin going real-time the algorithm will now catch spam link profiles more quickly and help keep sites from ranking well in SEO that really have no business ranking in the Google search results.