--- title: "RankBrain (2015): what Google's first AI ranking system does" url: https://seomadman.com/updates/rankbrain-2015 section: updates language: en published: 2026-09-26T00:00:00.000Z modified: 2026-09-26T00:00:00.000Z author: Adam Hafez topics: ["Core updates", "Content strategy"] --- # RankBrain (2015): what Google's first AI ranking system does ## The short answer RankBrain is a machine-learning system Google uses to understand how words in a search relate to concepts. Google first disclosed it to Bloomberg on 26 October 2015 and told Search Engine Land it had rolled out gradually in early 2015. Unlike most systems here, it was never retired: Google still lists it among its ranking systems. ## Key takeaways - Google first disclosed RankBrain in a Bloomberg interview with research scientist Greg Corrado on 26 October 2015. - Google told Search Engine Land that RankBrain rolled out gradually in early 2015, without giving a day. - Corrado said RankBrain had become the third-most important signal contributing to search results. - Google calls RankBrain its first deep learning system in Search and still lists it as an active system. - There is no RankBrain-specific optimization; Google's guidance is to write helpful, people-first content. ## What Google changed RankBrain added machine learning to how Google interprets searches. Google first described it publicly in an interview with Bloomberg, which reported that a "very large fraction" of the millions of queries a second were being "interpreted by an artificial intelligence system, nicknamed RankBrain." Greg Corrado, a Google senior research scientist, said the system helps with the 15 percent of daily queries Google's systems have never seen before. Google's own current description is shorter. Its ranking systems guide says RankBrain "is an AI system that helps us understand how words are related to concepts." In a 2022 post, Google called it "the first deep learning system deployed in Search." ## When it rolled out Google has never stated a launch day. The system was disclosed on 26 October 2015, and Google told Search Engine Land "there was a gradual rollout of RankBrain in early 2015" and that it had been fully live and global for a few months. The date on this page is the disclosure date, used because no launch day exists. There was no completion date, because RankBrain is a standing system rather than a one-off update. ## What is known about its impact The figures below are Google's own, given by Corrado to Bloomberg in October 2015: - RankBrain had become "the third-most important signal contributing to the result of a search query," Corrado said. - A "very large fraction" of queries were being interpreted by it at that time. Google did not publish site-level ranking effects, and RankBrain was not an update that sites won or lost from on a given day. It changed how queries were understood. ## What site owners should do RankBrain is still active: Google's ranking systems guide lists it among current systems, not in the retired section. Google has never published RankBrain-specific advice, and there is nothing to tune for it directly. What follows from how it works: - Write for the concepts a searcher means, not for exact-match phrases. Google says RankBrain can return relevant content even if it lacks all the words used in a search. - Follow Google's helpful content guidance: content created primarily for people, not to manipulate search engine rankings. - Do not add keyword variations to pages to catch every phrasing; that is what RankBrain exists to handle. ## How to check whether it affected you You cannot isolate RankBrain in your data. It rolled out gradually in 2015, before Search Console's 16 months of history, and it acts on how queries are interpreted rather than on a dated ranking change. The practical check today is in Search Console's Performance report: look at the queries a page ranks for that do not contain its target words. The [Google Algorithm Updates timeline](/updates) lists the dated updates around it. ## Related updates - [Hummingbird](/updates/hummingbird-2013) was Google's earlier overhaul of how it understands searches. - The [BERT update](/updates/bert-2019) was Google's next major language understanding system in Search. ## Frequently asked questions ### When did RankBrain launch? Google has not given a day. It first disclosed RankBrain to Bloomberg on 26 October 2015, and told Search Engine Land the system had rolled out gradually in early 2015 and had been fully live and global for a few months. This page uses the disclosure date. ### What does RankBrain do? Google describes it as an AI system that helps it understand how words are related to concepts, so it can return relevant content even when a page does not contain all the exact words used in a search. ### Is RankBrain still used? Yes. Google's ranking systems guide lists RankBrain as a current system, not a retired one, and a 2022 Google post said it continues to be one of the major AI systems powering Search. ### Can you optimize for RankBrain? Google has published no RankBrain-specific advice. Because it helps match searches to concepts rather than exact words, Google's general guidance on helpful, people-first content is the relevant guidance. ## Sources 1. [Google Turning Its Lucrative Web Search Over to AI Machines](https://www.bloomberg.com/news/articles/2015-10-26/google-turning-its-lucrative-web-search-over-to-ai-machines) - Bloomberg (primary) 2. [FAQ: All about the Google RankBrain algorithm](https://searchengineland.com/faq-all-about-the-new-google-rankbrain-algorithm-234440) - Search Engine Land 3. [How AI powers great search results](https://blog.google/products-and-platforms/products/search/how-ai-powers-great-search-results/) - Google The Keyword (primary) 4. [A guide to Google Search ranking systems](https://developers.google.com/search/docs/appearance/ranking-systems-guide) - Google Search Central (primary) 5. [Creating helpful, reliable, people-first content](https://developers.google.com/search/docs/fundamentals/creating-helpful-content) - Google Search Central (primary)