What an AI Overview actually is
An AI Overview is a generative summary that Google composes from a small set of source URLs (typically 3–8) at the top of the SERP for queries Google's models judge to be a good fit for a synthesized answer. The block links out to each source, and Google has confirmed these links produce real outbound clicks (Search Central, 2024). It is not a featured snippet — it is a generated paragraph, often with a list, often with images, that paraphrases multiple sources.
The system that powers AI Overviews is a Gemini-based model layered on top of Google's existing retrieval stack. The retrieval layer still surfaces candidate URLs the same way it does for blue links; the generative layer then decides which subset to cite when composing the answer.