Reranking
Reranking is a second sorting step in search: a system quickly gathers a large set of possibly useful documents, then scores each one again with a slower, more careful method and puts the best on top. In a 2019 paper, Rodrigo Nogueira and Kyunghyun Cho described the top results of this step feeding a tool that writes the answer.
Source: Nogueira and Cho, Passage Re-ranking with BERT (2019), checked October 29, 2026
What Reranking means for your business
Researchers call the first, fast step the first stage, and SEO writers sometimes call it first-pass retrieval. It's built to catch a lot quickly, and reranking is built to judge fewer carefully. Google Cloud sells a reranker to developers, its ranking API, which reorders documents by how well each one answers a query, including choosing which passages go to an AI tool.
ChatGPT, Perplexity and Google's AI Overviews don't publish their sorting steps in that detail, so we wouldn't claim to know them. What the research and the developer tools agree on is the order. A page has to be found in the first pass before any reranker can score it.
For a business, the first job is ordinary SEO: pages search engines can crawl and index, using the words buyers use. The second is the writing. In the 2019 paper, the reranker scores a passage against the question, not your whole site, so we'd make each section answer one question well.
If your page shows up for a question but AI answers quote a page that answers it more squarely, tightening each section around the question it answers is where we'd start.
Last reviewed October 29, 2026. All terms
How AI answers it today
On October 29, 2026, Google's AI Overview explained it as a two-stage process for developers, citing database and AI vendors' blogs, YouTube and Reddit, and no research papers. ChatGPT gave a similar developer explanation with before-and-after tables and cited nothing.
Our run through ChatGPT and Google's AI Overview, October 29, 2026. A sample, not what every buyer sees.
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