Matt Cutts, today announced on Twitter that Google has rolled out Panda 4.0 algorithm impacting ~7.5% of queries which can be noted by regular user while searching.
Google is rolling out our Panda 4.0 update starting today.
— Matt Cutts (@mattcutts) May 20, 2014
As we know that Google Panda deals with low quality spam contents and prevents sites ranking in Google results which have low quality contents.
Matt Cutt said that this is update and not algorithm refresh, and supposed to be softer and gentler as compared to previous versions.
Google Panda 4.0 affects different languages to different degrees, this algorithm is being said as softer stand towards websites as well as upcoming updates or changes will be based on this new algorithm calculation of Panda 4.0