RankBrain
RankBrain is the part of Google Search that works out how the words in a search relate to real-world ideas, so Google can return useful pages even when they don't contain every word someone typed. Google launched it in 2015 as its first deep learning system in Search, and its ranking systems guide still lists it today.
Source: Google Search Central, A guide to Google Search ranking systems, with The Keyword, How AI powers great search results (2022), checked October 29, 2026
What RankBrain means for your business
In a 2022 post on AI in Search, Google says RankBrain helps decide the best order for top results. Its example there is a long, roundabout question about what you call the consumer at the top of a food chain. RankBrain helps Google see that the person means animals and wants pages about apex predators.
There's nothing to switch on for RankBrain and no score to check. Google's ranking guide lists it as one system among many, beside BERT, neural matching, passage ranking and PageRank, its original system for reading links. We'd be wary of anyone selling RankBrain optimization as its own service.
We'd make sure each page answers one clear question in full, in plain words, so it's a good match however a buyer happens to phrase it. If customers describe their problem in their own words and your pages only use the trade name for it, writing pages in the words buyers use is the work we'd put first.
Last reviewed October 29, 2026. All terms
How AI answers it today
On October 29, 2026, Google's AI Overview cited Wikipedia and SEO blogs, none of Google's own pages, and said RankBrain tracks clicks and time on page, which Google's guide doesn't say. ChatGPT's definition was close to Google's but cited only SEO news sites.
Our run through ChatGPT and Google's AI Overview, October 29, 2026. A sample, not what every buyer sees.
Related terms in crawlers and technical access
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