A citation hero page is one of the handful of pages on your own site that earns most of your AI citations, while the majority of your pages earn none. It names the lopsided, within-site shape of citation distribution: engines cite a tight shortlist per answer, and your buyers ask a bounded, recurring set of questions, so citations compound onto whichever of your pages already win those recurring questions rather than spreading evenly across your site.
A citation hero page is defined by what actually gets cited, not by traffic, seniority, or being your homepage. The pages that win tend to answer one recurring question answer-first, carry high evidence density, stay fresh, and match the page format your category rewards. Which of your URLs qualify is frequently surprising, which is why hero pages are identified from measured cited pages rather than assumed.
This is a different axis from cross-web domain concentration — the finding that a few domains dominate all AI citations across the web. Hero-page concentration is inside your own site: of the pages you control, only a few get cited. Both are real; one is about which domains win the internet, the other about which of your pages win. Finding your hero pages and concentrating maintenance on them — while sending questions you can't win to earned coverage — is a core AI-visibility move, tracked over time as citation coverage and share of voice per engine.