Google rarely confirms core algorithm updates. They did confirm one back in May 2015 for us, but it is rare that they confirm these. So it is a big thing for Google to go on record that this update webmasters were seeing was related to the core update. Webmasters are still waiting for the Penguin update that was delayed and expected to be pushed sometime during this month. So there was a lot of confusion, with SEOs and webmasters thinking this update was Penguin-related. But the signs didn’t point to Penguin; it seemed more core search- or Panda-related. Now we know it was core search, and potentially also Panda, which is now baked into the core search algorithm. More on that in a few minutes over here. Get the full story at Search Engine Land and Search Engine Roundtable