What is the entity stack and how do you build one?

The entity stack is the full layered set of signals that together define an entity to search and AI systems, and the discipline is to build and maintain it as a coherent whole rather than as disconnected assets. The layers reinforce each other: the entity home (the official site with schema markup) anchors the identity; Wikidata provides the machine-readable structured record; Wikipedia, where notability supports it, supplies the authoritative narrative; authoritative directories and business references add corroboration; consistent, schema-marked social profiles signal active presence; and press citations supply third-party validation and co-occurrence signals. What makes it a stack rather than a list is the linkage and consistency – sameAs connections and matching descriptions that tie the layers into one recognized node. Building one means inventorying what exists, filling the gaps in priority order, and aligning the descriptions so the layers agree. We construct and maintain the entity stack as the core of the entity layer.