RankBrain
RankBrain is Google's 2015 machine-learning algorithm that interprets unfamiliar and ambiguous queries by recognising semantic patterns.
RankBrain was Google's first major step toward AI-driven search. It interprets never-before-seen queries (15% of daily searches) by connecting them to semantically related queries it does understand. Since 2016 one of the top-3 ranking factors. For SEO this means: optimise for intent and topical authority, not individual keywords.
Example
If someone searches 'what does a squirrel eat in january', RankBrain recognises this is semantically similar to 'winter squirrel feeding' and surfaces the same best pages, even if they don't contain the exact phrasing.
Frequently asked questions
How do I optimise for RankBrain?
Write for humans, not keywords. Cover full topical authority, use natural synonyms, answer follow-up questions, ensure clear structure and E-E-A-T.
Is RankBrain still relevant in 2026?
Yes, as part of a stack: RankBrain, BERT, MUM and newer LLM components work together. Core principle stays: understand intent > match keywords.
Related terms
Further reading
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