Google has confirmed that they’ve began rolling out the Penguin 4.0 algorithm. It is around two years ago that they released a Penguin update, called Penguin 3.0 in October 2014.
Penguin primarily focuses on unnatural links (that being said, it isn’t just about bad links). Up to now, the filter was only run periodically, with sites being re-evaluated each time.
The update is a “real time” algorithm, which means that once Google recrawls and reindexes your web pages, those signals will be immediately used in the new Penguin algorithm.
The 4.0 update works within the core search algorithm, meaning that websites might start to see fluctuations more often, particularly if a site has a poor backlink profile.
At The SEO Works we’re continuing to monitor the update and review the impact it has on our client’s sites, as well as continue to work within best practice for achieving great rankings.