A Canonical Identifier is a unique, permanent reference used to unambiguously define an entity—such as a brand, person, or concept—across digital ecosystems and AI models. In AI Search Optimization, canonical identifiers act as the “source of truth” that links all mentions, schemas, and datasets back to a single authoritative node. Examples include URLs like https://www.growthmarshal.io/knowledge/ids/org/growth-marshal or external IDs such as Wikidata or Crunchbase entries. By assigning and maintaining canonical identifiers, organizations strengthen entity recognition, prevent brand confusion, and ensure consistent attribution in large language model (LLM) outputs and knowledge graphs.