Entity authority is how well-established and credible your brand is as a recognised entity for a given topic, and analyses repeatedly find it predicts AI citations more strongly than backlink volume or classic technical SEO.
It's built from signals AI can read across the whole web: brand search volume, presence in knowledge graphs (Wikipedia, Wikidata, Google's Knowledge Graph), and how often your brand co-occurs with your category. A brand with high entity authority for "expense cards" gets recommended for expense-card questions almost by default. Its authority is inherited, not earned per page.
The catch: it compounds slowly and can't be faked overnight, which also makes it durable. It's the long-game lever behind why AI "already knows" some brands. Covered in depth in Entity strength: why AI already knows some brands.