What is Google AI Overviews

Full definition

AI Overviews (AIO) is the generative response block that Google displays at the top of the search results page — above paid ads and organic blue links. It was officially announced on May 14, 2024, at Google I/O as the replacement for the Search Generative Experience (SGE) and simultaneously rolled out to all US users without requiring activation in Search Labs.

The system runs on Google's Gemini model through a retrieval-augmented generation (RAG) process. Rather than synthesizing a response purely from the model's training data, the system retrieves relevant web pages in real time, extracts passages from them, and weaves those passages into a coherent answer, citing the source pages used. Beginning in mid-2025, Google started powering AI Overviews in the United States with Gemini 2.5 (Flash and Pro variants), improving reasoning depth and response speed.

Why it matters in 2026

SE Ranking (May 2025) detected AI Overviews in approximately 30% of tracked keywords in the United States — the highest share observed to that date. The feature was available in more than 200 countries and 40 languages. The AIO block occupies the zero position in the SERP, which reduces the click-through rate for organic results displayed below it. However, links cited inside the AIO block receive more clicks per impression than the same page would receive in a standard organic position for that same query, according to data reported by Google.

The implication for any visibility strategy is that being cited in AI Overviews can be more valuable than holding the number-one organic position without being referenced in the generative block.

How it works

1. The user submits a query to Google Search.
2. Gemini evaluates whether the query warrants a generative response — not all queries trigger AI Overviews.
3. The RAG system retrieves a set of relevant web pages from Google's index.
4. Gemini synthesizes a coherent response by integrating passages from those pages.
5. The AIO block is displayed in the zero position with links to the source pages used.
6. The user can expand the block to see additional detail and more sources.

Difference from AI Mode and Featured Snippets

Format	SERP position	Model	Sources shown	Interactivity
Featured Snippet	Classic zero position	No generative AI	1 URL	None
AI Overviews	Generative zero position	Gemini (RAG)	Multiple URLs	Expandable
AI Mode	Separate conversational tab	Gemini 2.0 (RAG + query fan-out)	Multiple URLs	Follow-up questions

Related terms

Google AI Mode, AEO (Answer Engine Optimization), GEO (Generative Engine Optimization).