# Concepts This section covers the core concepts behind ZeroID's identity model. Read these before designing your production tenant or writing authorization logic — the terminology and models here appear throughout the SDK, token payloads, and policy configuration. * [**Identity Model**](/agent-identity-zeroid/concepts/identity-model.md) — How agents, services, applications, and MCP servers are modeled as first-class identities. Covers tenant structure, identity types, sub-types, trust levels, WIMSE/SPIFFE URIs, and the owner/principal/actor distinction. * [**Token Flows**](/agent-identity-zeroid/concepts/token-flows.md) — The OAuth 2.0 grant types ZeroID supports (`api_key`, `client_credentials`, `jwt_bearer`, `token_exchange`, `authorization_code`, `refresh_token`) and when to use each one. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.highflame.ai/agent-identity-zeroid/concepts.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.