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 advertisements and organic results. It was officially announced on 14 May 2024 at Google I/O as the replacement for the Search Generative Experience (SGE) and deployed simultaneously to all US users without requiring opt-in via Search Labs.

The system operates on Google's Gemini model through a retrieval-augmented generation (RAG) process: rather than synthesising solely from the model's pre-training data, the system retrieves relevant web pages in real time, extracts fragments, and integrates them into the response whilst citing the sources used. From mid-2025, Google began using Gemini 2.5 (Flash and Pro variants) to power AI Overviews in the United States, improving reasoning depth and response speed.

Why it matters in 2026

SE Ranking detected AI Overviews in approximately 30% of tracked keywords in the United States as of May 2025, the highest percentage observed to that date. The feature was available across more than 200 countries and 40 languages. The block occupies position zero of the SERP, which reduces the click-through rate of organic results ranked below it.

However, links cited within the AIO block itself receive more clicks than if the same page had appeared as a conventional organic result for that query, according to data declared by Google. The implication for any digital visibility strategy is that being cited inside AI Overviews can be more commercially valuable than holding the first organic position without being referenced in the generative block.

How it works

1. The user enters a query in Google Search.
2. Gemini evaluates whether the query warrants a generative response — not all queries trigger one.
3. The RAG system retrieves a set of relevant web pages from Google's index.
4. Gemini synthesises a coherent response by integrating fragments from those pages.
5. The AIO block is displayed at position zero with links to the sources used.
6. The user can expand the block to view further detail and additional sources.

Difference from AI Mode and Featured Snippets

Format	Position in SERP	Model	Sources shown	Interactivity
Featured Snippet	Classic position 0	No generative AI	1 URL	None
AI Overviews	Generative position 0	Gemini (RAG)	Multiple URLs	Expandable
AI Mode	Separate conversational tab	Gemini 2.0 + query fan-out	Multiple URLs	Follow-up questions

Related terms

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