RankBrain is Google’s machine-learning artificial intelligence system designed to help Google to process search results and deliver more relevant information to users. It is a part of the Google’s Hummingbird search algorithm. It can learn and recognize new patterns and then revisit SERPs to provide more relevant information.
It has the ability to embed the written language into mathematical entities called vectors that Google can understand. For example, if it does not understand a sentence, it can guess its meaning with similar words or sentences and filter the information accordingly to provide accurate and relevant results to users.