# Glossary
| Term | Acronym | Definition | Synonym / Related |
| :------------------------------------- | :-------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Action Authorization | | A process where a Verifier challenges an Agent to provide proof that it is authorized to perform an action on behalf of a User. | |
| Agent Payments Protocol | AP2 | An open protocol designed to enable AI agents to securely interoperate and complete payments autonomously. | |
| Agent Provider | | An entity that provides the Agent to the User. Can also be a trusted party for Verifiers to construct Mandates directly. | |
| Agent2Agent Protocol | [A2A](https://a2a-protocol.org/latest/) | An open standard for secure, collaborative communication and task management between diverse AI agents, regardless of their underlying frameworks.
**Context:** AP2 can be implemented as an extension of A2A to facilitate financial transactions, with a focus on high-trust agentic payments. | |
| Agentic payments | | Payment flows in which autonomous AI Agents are facilitating the payment. | |
| Checkout Mandate | | A Mandate used for authorizing the completion of a checkout. | |
| Closed Mandate | | A Mandate that is bound to a particular action with a Verifier to authorize the agent to perform an action. | |
| Credentials Provider | CP | A secure entity, like a digital wallet, responsible for managing and executing the user's payment and identity credentials. | |
| Deterministic cryptographical proof | | A unique mathematical proof that could be linked to a hardware device. | |
| Dynamic Linking | | A core requirement for Strong Customer Authentication (SCA), involving the inclusion of specific transaction details within a Payment Credential to link the SCA to that transaction.
**Context:** Ensures the payer explicitly consents to transaction details like amount and payee. | |
| Mandate Content | | The specific payload of a Mandate created by the Shopping Agent and rendered to the User, detailing actions the agent handles. | |
| Mandate Delegation | | A process where a User authorizes an Agent to perform an action on their behalf. | |
| Mandate Receipt | | A Verifier-signed JWT indicating the result of the action authorization. | |
| Merchant Endpoint (Or Remote Endpoint) | ME, RE | The web interface or AI agent representing the seller, showcasing products and negotiating the cart. | |
| Merchant Payment Processor | MPP | The entity responsible for constructing and sending the transaction authorization message to the payment ecosystem. | Merchant PSP |
| Model Context Protocol | MCP | A protocol standardizing how AI models and agents connect to and interact with external resources like tools, APIs, and data sources. | |
| Open Mandate | | A Mandate that has not yet been bound to a particular action. It possesses constraints to be applied to a closed mandate to ensure it's validity. | |
| Payee | | A person or entity who is the intended recipient of funds from a payment transaction.
**Context:** Can request attestations along with payment confirmation. | Merchant, Creditor Name |
| Payer | | A person or entity who holds a payment account, allows a payment order from that account.
**Context:** Initiates payment orders. | User, Holder |
| Payment Agent | | A proposed key role in agent payments responsible for selecting the ideal payment method, validating payment details, and handling errors.
**Context:** A Payment Agent is not a necessary requirement to participate in the protocol. MCP-based endpoints can also play similar roles. | |
| Payment Credential | | A credential or instrument (or reference to one) which can be charged towards a payment. | Electronic Attestation of Attributes (EAA), Payment Wallet Attestation (PWA), Digital Payment Credentials (DPC), Payment Means Attestation, SPC Credential |
| Payment Initiation Service Provider | PISP | A service provider that initiates payments on behalf of the user. | |
| Payment Mandate | | A Mandate used for authorizing the payment for a particular checkout. | |
| Strong Customer Authentication | SCA | A process required by regulatory frameworks for online identification and transaction initiation in financial services.
**Context:** Central to the Payments Rulebook, ensuring security and dynamic linking of transactions. | Strong User Authentication, Integrated SCA |
| Trusted Surface | | A secure, non-agentic interface that renders Mandate Content to the User for authorization and consent. The result of which is a Mandate. | |
| Universal Commerce Protocol (UCP) | | A protocol providing a Checkout Object standard when used with the Checkout Mandate. | |
| User | | The human initiating the task and providing financial authority. | |
| User Agent a.k.a. Shopping Agent | UA, SA | The AI surface interacts directly with the user, understanding their needs, and coordinating the purchase. | |
| Verifiable digital credential | VDC | An Issuer-signed credential (i.e., a set of Claims) whose authenticity can be verified.
**Context:** Typically bound to a cryptographic key and used in the issuer-holder-verifier model. | Digital credential, Verifiable Credential |
| Verifiable Presentation | VP | A presentation of one or more VDCs that includes a cryptographic proof of holder binding, created in response to a request from a Verifier.
**Context:** Allows a Verifier to confirm that the Holder intended the presentation for them and may reveal only a subset of claims. | |