What it means
Microsoft Prometheus was the model Microsoft built to power Bing's early AI chat, announced in February 2023. It combined the live Bing search index with a large language model so the chatbot could answer questions using fresh web results rather than only its training data. Kevin grouped Prometheus with Google Bard as the most significant change to Search at the time, and it was an early example of grounding an LLM in a search index.
Why it matters
Prometheus was the moment Bing turned AI into a competitive weapon against Google. Microsoft scheduled its reveal one day before Google's and presented a sharper vision for AI Search and Edge, giving Bing its first credible path to gain more than its 6% market share. Pairing a search index with a model also pointed at the technique, retrieval augmented generation, that now underpins most AI answers.
Picture a B2B brand in early 2023 that had ignored Bing for years. Once Prometheus made Bing Chat genuinely useful, that brand suddenly had a reason to check whether Bing was crawling its pages and citing them in chat answers, because a small index with AI on top could now send qualified traffic.
How to use this knowledge
Stop ignoring Bing. Prometheus showed that an underdog index plus a model can become a real referral source, so confirm Bingbot can crawl and render your key pages.
Understand grounding. Learn how retrieval augmented generation pulls live results into answers, because that mechanism decides which sites get cited.
Watch the incumbents react. Use Bing as a reminder that a fast challenger can force the market leader into a rushed response.
Build for citation. Structure content so an index-plus-model system can lift clean, accurate snippets from your pages.
Growth Memo guidance
Last week, Google and Bing introduced the most significant change to Search so far: Bard and Prometheus. They don't just introduce a new era of search but also the first big opportunity Bing has to gain more than its 6% market share.
Microsoft seemingly scheduled its announcement intentionally one day before Google's and did a great job presenting an exciting vision for AI Search and Edge.
One of the most important countermeasures to hallucination is ground. Tech like RAG (Retrieval Augmented Generation) allows search engines to return more factually correct information by grounding LLM answers in classic search.
Google Bard — Google's competing chatbot, announced one day after Prometheus.
Retrieval augmented generation (RAG) — the grounding technique that lets an index feed an LLM live results.
Bing Chat — the consumer product Prometheus powered.
Generative AI Search — the broader category Prometheus helped launch.
Hallucination — the accuracy risk that grounding in a search index is meant to reduce.