Google has made the official announcement that an algorithm update, Panda 4.2, was rolled out over the weekend.
The Panda Update was first introduced by Google back in 2011. It's a search filter that aims to keep sites with sub-par content away from the top of search results.
It's been nearly 10 months since Google last unleashed a Panda refresh – Panda 4.1 rolled out in September 2014.
Panda 4.2 has, for the most part, gone unnoticed this time around because the update is planned to roll out very slowly – but Google has stated that the update will eventually impact 2-3% of all English search queries.
Unlike the recent Mobile-friendly Update which penalized/rewarded on a page-by-page basis, Panda is a site-wide algorithm. Although, Google has stated that the update can and will take months to completely roll out. Any impact on your website will not happen immediately – but over time – and different parts of your website will likely be impacted separately as the algorithm rolls out over the next few months.