# Grounding

Grounding is the step that ties a generated answer to retrieved source documents, so the response reflects — and can cite — specific material rather than the model's parameters alone. The UK's CMA treats it as a distinct use of publisher content, separate from training and fine-tuning.

Grounding is what makes citation possible, and it is also what makes an answer inherit whatever the retrieval brought in. Google demonstrated both halves in one statement: asked about an AI Overview that answered near-identical queries differently, Google said its system was picking up particular web pages for that specific search and that the behavior was not present for all queries — the engine locating the answer in grounded sources rather than in the model. The failure mode has a research literature: the GPE benchmark simulates generative-engine-optimization attacks by controlling evidence sources and poisoning ratios, and finds verification systems degrade under poisoning in ways clean-data evaluation never reveals.

The regulatory record is what turned grounding from an architecture term into a controllable use. The UK CMA's Publisher Conduct Requirement forces Google to let publishers opt out of having content used for AI training, fine-tuning, and the grounding behind AI Overviews and AI Mode answers — three separate permissions, named separately. Google must also add clearer attribution links and supply publishers with impressions, clicks and click-through rate through a platform such as Search Console.

Grounding is where the visibility metrics are counted. Bing Webmaster Tools' AI Performance reports added Citation Share in preview in June 2026, and grounded answers are the only answers with citations to share. There is a demand-side reason to care which sources ground an answer: an AOP/Ipsos survey of 1,000 UK adults found trust in an AI answer ran above 90% when it cited a fully trusted news source, and about 25% for a neutral one.

**What does grounding mean in AI search?** Composing an answer from retrieved source documents rather than from the model's parameters alone — the step that lets an answer cite specific pages, and that makes the answer only as good as the sources retrieved.

**What is a grounding query?** A query the engine answered by retrieving and citing sources — the unit AI-visibility reporting counts citation share against. Bing Webmaster Tools added Citation Share to its AI Performance reports in preview in June 2026.

**Can publishers opt out of having their content used for grounding?** In the UK, yes. The CMA's Publisher Conduct Requirement requires Google to let publishers exclude content from AI training, fine-tuning, and the grounding behind AI Overviews and AI Mode.

Canonical: https://anythingengineoptimization.com/glossary/grounding/
From the Anything Engine Optimization glossary — https://anythingengineoptimization.com/glossary/