What is Rankbrain?
RankBrain - announced by Google in October 2015 - is an important part of Google's core algorithm that uses machine learning to determine and present the most relevant search results to search engine queries.
While the exact working of RankBrain is a secret, Google has confirmed that RankBrain is one of the hundreds of "signals" within its algorithm.
It uses AI to interpret complex queries, understands the intent behind searches, and present the most relevant search results.
RankBrain can make associations between words and concepts, which allows it to handle queries it hasn't seen before and provide relevant search results.