The Google Knowledge Graph is Google's structured database of entities — people, places, organizations, products, events, concepts — and the relationships between them. Launched in 2012, it powers the right-side "knowledge panel" in Google SERPs and is heavily used by AI Overviews to ground claims in factual entity records.
For AEO specifically, Knowledge Graph presence is a major AIO citation signal. AIO's answer composer prefers to cite sources tied to a recognized entity because it can ground the claim against the entity's record. Pages with strong Organization schema (sameAs links to Wikipedia, Wikidata, LinkedIn, Twitter) and consistent entity-aware brand presence cite more reliably.
For small or new brands without organic Knowledge Graph presence, the deliberate path is to ship full Organization schema with sameAs links to social profiles, claim a Google Business Profile, register on Crunchbase / LinkedIn with consistent name-address-phone (NAP) data, and pursue Wikipedia coverage where defensibly notable. The Knowledge Graph reflects what Google can verify — consistent multi-source presence is the building material.
The Knowledge Graph is invisible to the user but consequential for AIO and increasingly for ChatGPT (which has begun using its own entity graph for similar grounding).