Gemini

AI Mode passed 1 billion monthly users roughly a year after its debut, with query volume more than doubling every quarter since launch^[3]. Measured across 55,393 trending queries sampled over 40 days in 2026, an AI Overview appeared on 13.7% of queries overall and on 64.7% of question-form queries^[4].

Grounding is the mechanism that ties a Gemini request to live results: one request may trigger one or more queries to Google Search, so the model answers from current pages instead of training data alone^[5]. It reached the Gemini API and Google AI Studio on 31 October 2024^[6]. Gemini 3.x models carry 5,000 free grounded search requests a month, shared across the 3.x family^[7]. Past the free allocation, grounding on the 2.5 models is billed at 35 dollars per 1,000 grounded prompts^[8].

Citation is not a mirror of the ranking. Nearly 30% of the domains cited in AI Overviews appear nowhere in Google's own first page of organic results for the same query, which points to a selection mechanism distinct from the ranking algorithm^[9]. Selection also tracks intent: in a study of 31 SaaS keywords, educational articles supplied 70.2% of citations on informational queries, while listicles and buying guides led on commercial ones^[10]. The same study saw Google swap at least one cited source between repeated runs for 52% of keywords^[11].

The answer text and the cited page do not always agree. Splitting AI Overview answers into 98,020 atomic claims, one measurement study found 11.0% unsupported by the pages cited beside them, mostly through omission rather than contradiction^[12]. The SaaS keyword study put direct support at 64.7% of the claims it examined^[11]. Publishers absorb the cost of the arrangement: well over half of AI Overview cited pages carry display advertising, so an answer that satisfies the query removes the click that paid for the page^[13]. See zero-click search and E-E-A-T.

The links themselves fail as well. In the Tow Center's audit of eight AI search tools, more than half of the responses from Gemini and Grok 3 cited fabricated or broken URLs^[14]. That is a separate defect from an unsupported claim, and it is invisible to a reader who does not follow the link. Citation accuracy covers the audit and its method.