Grounding
Consensus definition
Grounding is a provider feature — for example Grounding with Google Search — that connects the model to real-time web content and returns grounding metadata (the search queries it ran and the sources it used)1. Its stated purpose is to reduce hallucination and let the model cite verifiable sources beyond its training cutoff. Bing treats grounding as an indexing paradigm of its own and reports the grounding queries behind Copilot and Bing AI answers to site owners2.
rhinegold operator caution
Rhinegold's caution: grounding is a mechanism, not a visible outcome. A grounded answer does not guarantee a visible citation — grounding metadata is frequently not surfaced to the end user, and providers expose it inconsistently. Do not infer a citation from the fact that grounding happened, and do not infer that grounding did not happen from the absence of a visible citation.
Operational use
Grounding is the right lens for understanding why a brand does or does not get cited: it determines the candidate pool of sources an answer can draw on in the first place.
Measurement boundary
What can be observed depends on the access path. Through the API, several providers return grounding metadata per answer — whether a web search ran, which queries, which URLs1 — so grounding is measurable there, answer by answer. In the consumer interfaces it is not: the end user sees a citation or nothing, and the mechanism stays hidden. Bing Webmaster Tools reports the grounding queries that led to a site's citations across Copilot and Bing2; Google reports impressions in its generative features but not the grounding behind them3. Behaviour is provider-specific: the same page can sit in one provider's source pool and never enter another's, and a new page can take weeks to appear in any pool. Grounding also fails in a specific way: when retrieval returns nothing useful, the model answers from memory anyway.
What can still be observed
The downstream Citation Rate is observable everywhere. Where the API exposes grounding metadata, the set of queries and domains it pulled is too — and in measurement practice nearly all citations turn out to come from that grounding step, not from the model's memory. Site owners can also decide whether to be in Google's pool at all: a Search Console toggle opts a site out of AI Overviews and AI Mode without, Google says, affecting ranking elsewhere4.
Distinct from
Against Citation Rate, which is the visible attribution — grounding is the retrieval step beneath it. Against Mention Rate, which is mere presence. And against GEO, where improving retrievability is how you try to enter the grounding pool.
Operational note
Common mistakes
- Equating grounding with citation — a grounded answer need not cite you visibly.
- Assuming every provider grounds every answer.
- Reading the absence of a citation as the absence of grounding.
- Writing "grounding cannot be measured" when it can — through the API, per answer — and only the consumer interface hides it.
Where consensus is missing
Providers define and expose grounding differently, and there is no cross-provider standard for grounding transparency — so grounding behaviour cannot be compared like-for-like across engines.
Sources & deeper reading
- 1Google — Grounding with Google Search (Gemini API documentation): mechanism, grounding metadata, citations
- 2Bing Webmaster Tools — "New AI Visibility Insights: Intents, Topics, Citation Share, Compare" (16 June 2026; AI Performance report since 10 February 2026: citations and grounding queries across Copilot, Bing AI answers and partner surfaces)
- 3Search Console Help — "Generative AI performance report (Search)" (impressions only, AI Overviews and AI Mode combined; all websites from 31 August 2026)
- rhinegold Insights, Episode 05 — Content Architecture for LLM Authority
- rhinegold grounding-trace analysis across providers — applied with engaged clients and partners.
Update history
- 2026-10-08 — Corrected the claim that grounding is never measured directly: through the API, providers return grounding metadata per answer; only the consumer interface hides it. Added Bing's grounding queries and Citation Share, Google's Generative AI report and opt-out toggle, and the link to Query Fan-Out.