A zero-click search is a query resolved entirely on the results page or inside an AI answer — the user gets what they need without visiting any website.
Zero-click behavior predates AI (featured snippets, knowledge panels), but AI answers accelerate it sharply: a complete, personalized recommendation leaves little reason to click through. Traffic-based analytics go dark exactly where the decision is being made.
That is the measurement case for AI visibility tracking: if the decision happens inside the answer, you have to measure the answer — impressions and sessions cannot see it.