Google Knowledge Graph unique entity identifier. Obtain through schema.org implementation, Wikidata entity creation, and corroboration from authoritative sources. Check using Google Knowledge Graph Search API. Absence means entity is not disambiguated in Google’s system — retrieval disadvantage in all Google-mediated contexts. Required for identity sovereignty. Build through: complete schema markup, Wikipedia article (if eligible), Wikidata item, consistent NAP across tier-1 directories. KGMID is persistent — once assigned, maintain through schema consistency.