# All terms

- **[ACP (three protocols)](/terms/acp/)**: ACP refers to three unrelated protocols from three organisations at three different steps.
- **[Agent Card](/terms/agent-card/)**: An Agent Card is a JSON document that an A2A server publishes to describe itself to other agents: its identity (name, description, provider), its service endpoint URL, the A2A capabilities it supports (streaming, push notifications), its authentication schemes, and the skills it offers, each with an id, description, and input/output modes.
- **[Agentic web](/terms/agentic-web/)**: The agentic web is the ordinary web plus a layer of conventions that let software agents, rather than people in browsers, discover what a site offers, prove who they are, learn what they may do, read content, invoke capabilities, coordinate with other agents, pay, present results, and be held to account.
- **[Agentmap directive](/terms/agentmap/)**: Agentmap is a line a publisher can add to robots.txt, of the form Agentmap: https://example.com/entries.json, that points a crawler at a source of Agentic Resource Discovery (ARD) entries as an alternative to relying solely on the well-known manifest path.
- **[AI crawler tokens](/terms/ai-crawler-tokens/)**: AI crawler tokens are the User-agent names AI companies document for use in robots.txt under RFC 9309, split by purpose rather than treated as one identity.
- **[Facilitator](/terms/facilitator/)**: A facilitator in the x402 protocol is an optional third-party service that verifies and settles blockchain payments on behalf of a resource server, so the server does not need its own blockchain connectivity or payment-verification logic.
- **[Mandate](/terms/mandate/)**: A mandate in Google's Agent Payments Protocol (AP2) is a cryptographically signed, verifiable credential that authorises an agent to act on a person's behalf for a specific purchase step.
- **[MCP Server Card](/terms/server-card/)**: A Server Card is a proposed static, discoverable document that describes an MCP server: what it is, who publishes it, and how to reach it, without requiring a client to first open an MCP session.
- **[Origin trial](/terms/origin-trial/)**: An origin trial is Chrome's mechanism for shipping an experimental web-platform feature to real sites for a limited time before deciding whether to ship it broadly: a developer registers a specific origin, receives a token, and includes that token as a meta tag or HTTP header so the feature activates for visitors to that origin without requiring them to flip browser flags.
- **[Well-known URI](/terms/well-known/)**: A well-known URI is a path beginning /.well-known/ at the root of an origin, reserved by RFC 8615 (May 2019, obsoleting RFC 5785) so that applications needing site-wide metadata do not have to negotiate arbitrary paths or risk colliding with a site's existing URL space.