Google uses RankBrain for every search, impacts rankings of "lots" of them

Google is now using its RankBrain machine learning system to process every query that the search engine handles, and the system is changing the rankings of lots of queries. The news emerged this week as part of Steven Levy's Backchannel story about machine learning efforts at Google. Google is characteristically fuzzy on exactly how it improves search (something to do with the long tail? Of the hundreds of "signals" Google search uses when it calculates its rankings (a signal might be the user's geographical location, or whether the headline on a page matches the text in the query), RankBrain is now rated as the third most useful. We've already heard before that RankBrain is considered the most useful search ranking signal, behind content and links.