Query fan-out

Query fan-out describes the engine behaviour of expanding a single user query into multiple sub-queries that together cover the implicit intents. A user query like "best identity provider for B2B SaaS" might fan out to: "what is B2B SaaS identity"; "Auth0 features"; "Okta enterprise pricing"; "identity provider comparison"; "B2B SSO requirements"; each of those is retrieved independently and sources from each contribute to the final synthesised answer.

Fan-out was made public-facing by Google's AI Mode in 2024-2025 and is now standard behaviour across the major answer engines, with varying transparency. Perplexity surfaces the fan-out as visible sub-questions; ChatGPT Search and Claude run it internally; AI Overviews uses it without exposing it.

For AEO and GEO, fan-out has two practical implications:

1. You can be cited for queries you don't explicitly target. A page on "Auth0 features" might be cited in an answer to "best identity provider for B2B SaaS" because the engine's fan-out generated a sub-query that matched your page. The retrieval surface expands beyond the literal query.
2. Topical depth matters more than ever. An engine that fans out a query into 5-7 sub-queries will retrieve from sites with broad topical coverage more often than from sites with a single targeted page. The topical authority discipline is the answer.

Tactically, optimising for fan-out means broad, internally-linked coverage of a topic, not narrow keyword targeting. The sub-queries the engine generates aren't predictable; the defence is to cover the topic comprehensively enough that any plausible sub-query lands somewhere on your domain.