What is Rankbrain?
RankBrain is an algorithm that uses machine learning to determine and present the most relevant results to search engine queries.
It was introduced by Google in October 2015 as part of Google's core algorithm.
While the exact working is of course not publically known, Google has confirmed that RankBrain is one of the hundreds of ranking signals within its algorithm.
It uses AI to interpret complex queries, identify the relationship between terms, understand the intent and present the most relevant results.