As with so many things Google, no one can say exactly what it is. RankBrain is part of Google’s search algorithm. It’s an Artificial Intelligence (AI) system used to process billions of web pages to help determine which results are the most relevant, in particular, queries that are new and not necessarily related to specific keywords (to really dumb down the explanation). There isn’t a way to optimize websites for RankBrain other than to continue to focus on quality content because RankBrain is less about keywords.
