What is Query Fan-Out and how do I map follow-up questions for AI Overview optimization?

Query Fan-Out refers to the latent follow-up questions users naturally ask after getting an initial answer. AI models predict these to generate comprehensive summaries. To map them: 1) Use AI tools with prompts like "What are the 5 most likely follow-up questions for [topic]?", 2) Cross-reference with Google's "People Also Ask" box, 3) Structure your content to answer the primary question AND its natural follow-ups (specific use cases, problems, comparisons). If your content only answers the main query but misses fan-out questions, you have a depth gap that prevents inclusion in AI Overviews.