# The Agentic Commerce Glossary: 30+ Terms Every Merchant Needs to Know

*Last updated: March 2026*

Agentic commerce has introduced an entirely new vocabulary to retail and e-commerce. Whether you are a merchant evaluating AI-driven sales channels, a developer integrating commerce protocols, or a strategist mapping the future of online retail, this glossary defines every term you need to understand. Bookmark this page -- it is the single reference you need to navigate the agentic commerce landscape.

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## Glossary (A-Z)

**A2A (Agent-to-Agent Protocol)**
An open protocol launched by Google in April 2025 that enables communication and interoperability between AI agents. A2A operates horizontally, defining how multiple agents collaborate, delegate tasks, and exchange information across organizational boundaries. It is governed by the Linux Foundation as an open-source project, with over 50 technology partners including Salesforce, Accenture, MongoDB, and LangChain. Merchants should care because A2A is how a shopping agent on one platform can coordinate with a shipping agent, a payment agent, or a customer service agent on another -- enabling multi-step commerce workflows that no single agent could handle alone. Key concepts include Agent Cards, Tasks, Messages, Artifacts, and Streaming. See also: Agent Card, MCP.

**ACP (Agentic Commerce Protocol)**
An open standard co-developed by OpenAI and Stripe that enables programmatic commerce flows between buyers, AI agents, and businesses. ACP is a platform-mediated commerce layer: merchants submit product data to OpenAI, Stripe handles all payments, and ChatGPT surfaces products to users during conversations. It has been live in ChatGPT since September 2025, with Instant Checkout launching on February 16, 2026. OpenAI charges merchants a 4 percent transaction fee on completed purchases, in addition to Stripe's standard processing fees. As of launch, ACP requires a paid Shopify plan, Shopify Payments enabled, and US-based operations. See also: UCP, Instant Checkout, SharedPaymentToken.

**AEO (Answer Engine Optimization)**
The process of securing prominent placement in AI-generated answers on platforms like ChatGPT, Google AI Overviews, Gemini, and Perplexity. AEO is largely synonymous with GEO, though AEO emphasizes structured extraction in standard search engines while GEO emphasizes AI-driven response systems. Other synonyms include AI SEO, AIO, and AI search optimization. According to McKinsey, 44 percent of AI-powered search users consider AI their primary source of insight, ahead of traditional search. Merchants who optimize for AEO ensure their products appear when consumers ask AI agents for purchase recommendations. See also: GEO.

**Agent Card**
A JSON document in the A2A protocol that serves as a digital business card for an AI agent. An Agent Card is published by agent servers and contains the agent's identity (name, description, provider), service endpoint URL, supported capabilities (streaming, push notifications), authentication requirements, and skills describing what the agent can do. Agents discover each other through Agent Cards via central registries, direct URLs, or directory services. Agent Cards may be digitally signed using JSON Web Signature (JWS) to ensure authenticity. Think of it as a DNS SRV record combined with a capability manifest for AI agents. See also: A2A.

**Agent Payments Protocol (AP2)**
An open protocol developed by Google and released under an Apache 2.0 license that enables AI agents to make payments on behalf of users safely, securely, and in a decentralized, privacy-protecting manner. AP2 extends A2A and MCP with constructs needed for secure, accountable, and authorized commerce. It launched with over 60 initial partners including Mastercard, Adyen, PayPal, Coinbase, and Visa. AP2's key innovation is the use of Verifiable Digital Credentials (VDCs) to engineer trust into agent-led transactions, particularly in "human-not-present" scenarios where the user is not actively supervising the purchase. Initial support covers pull payments (credit and debit cards), with push payments (UPI, PIX, real-time bank transfers) and digital currencies on the roadmap. See also: Cart Mandate, Intent Mandate, Payment Mandate, VDC.

**Agentic Commerce**
A paradigm where AI agents act on behalf of consumers or businesses to research, negotiate, and complete purchases autonomously. Agentic commerce shifts the buying experience from manual search and checkout to autonomous digital buyers. It represents the transition from "I am buying this product" to "solve this problem for me within my budget." Early 2026 data shows agentic traffic converts at nearly 9x the rate of traditional search (19.8 percent average versus 2.8 percent for organic search), with cart abandonment dropping from approximately 70 percent to under 5 percent. This is the umbrella concept that encompasses all the protocols, tools, and practices in this glossary. See also: Shopping Agent, Buyer Agent.

**Agentic Storefronts**
A Shopify feature in early access since January 2026 that allows merchants to set up their product data once and have it surfaced everywhere AI agents operate, including ChatGPT, Microsoft Copilot, Google AI Mode, Gemini, and other agent surfaces. Agentic Storefronts are managed centrally from the Shopify Admin. The core value proposition is single data source, multi-agent distribution -- no per-platform integration is required. This is Shopify's answer to the fragmentation challenge of supporting multiple agentic commerce protocols simultaneously. See also: UCP, ACP.

**Buy for Me**
A feature in Google's AI Mode (part of Google Search) that enables users to purchase products directly within the AI-generated search experience without navigating to the merchant's website. Buy for Me leverages UCP to communicate with merchant endpoints, handling product selection, checkout, and payment within the Google interface. It represents Google's consumer-facing implementation of agentic commerce, analogous to OpenAI's Instant Checkout for ChatGPT. This feature matters for merchants because it creates a new conversion channel with significantly higher intent than traditional search clicks. See also: UCP, Instant Checkout.

**Buyer Agent (Shopping Agent)**
The AI agent acting on behalf of the consumer in an agentic commerce transaction. A Buyer Agent interprets user intent, discovers products across merchants, evaluates options, negotiates terms, and executes transactions. In ACP, this role is played by ChatGPT. In UCP, any protocol-compliant agent can serve as a Buyer Agent. Unlike a recommendation engine, a Buyer Agent can autonomously complete the entire transaction loop from understanding intent to executing payment. See also: Seller Agent, Shopping Agent.

**Capability Negotiation**
The process by which an agent and a merchant compute what they can mutually support for a given transaction. Both parties publish profiles declaring their capabilities; the merchant computes the intersection -- which capabilities both support, which payment handlers overlap, which extensions are mutually understood -- and responds with the negotiated result. Capability Negotiation happens per-transaction: changing the cart, buyer location, or any other variable can shift available capabilities. This mirrors HTTP content negotiation and is a core mechanism of UCP. See also: UCP, Merchant Profile, .well-known/ucp.

**Cart Mandate**
A Verifiable Digital Credential used in AP2 when the user is present to authorize a purchase. The Cart Mandate is generated by the merchant and cryptographically signed by the user via their device, binding authorization to a specific transaction with specific items, quantities, and prices. For example, a user reviews a cart in an agent interface and confirms "Buy this," generating a Cart Mandate. This is the standard authorization mechanism for supervised agentic purchases. See also: Intent Mandate, Payment Mandate, VDC.

**Checkout Session**
A UCP core primitive representing a single commerce transaction in progress. A Checkout Session contains line items, totals, shipping information, and payment state. It is created when an agent initiates a purchase and persists until the transaction completes or expires. UCP defines three checkout states: incomplete (missing required information), requires_escalation (buyer input needed), and ready_for_complete (all information collected, agent can finalize). Checkout Sessions are the fundamental unit of transaction tracking in agentic commerce. See also: UCP, Embedded Checkout Protocol.

**Copilot Checkout**
Microsoft's implementation of agentic commerce within its Copilot AI assistant. Copilot Checkout represents a third player alongside Google's Buy for Me and OpenAI's Instant Checkout, using a platform-mediated approach similar to ACP. While less documented than UCP or ACP as of March 2026, Copilot Checkout is worth monitoring as Microsoft's entry into AI-driven retail. UCP remains the only protocol that works across all major agent platforms, including Copilot. See also: Instant Checkout, Buy for Me.

**Delegate Payment**
A transaction pattern in agentic commerce where the AI agent handles payment processing on behalf of the user without the user directly interacting with a payment form. In ACP, delegation occurs through SharedPaymentTokens -- tokenized payment credentials scoped to a specific amount and seller. In AP2, delegation is governed by Mandates (Intent, Cart, or Payment) that cryptographically define the agent's authority. Delegate Payment is the mechanism that enables truly autonomous purchasing. See also: SharedPaymentToken, Cart Mandate.

**Direct Offers**
Product listings or deals that merchants make available directly to AI agents for surfacing to consumers, bypassing traditional search engine result pages. In UCP, Direct Offers are published through the merchant's product catalog endpoints and discovered via the .well-known/ucp manifest. In ACP, they are submitted to OpenAI's centralized catalog. Direct Offers are significant because they represent a new channel where the merchant's products compete on structured data quality and agent compatibility rather than SEO ranking factors alone. See also: Agentic Storefronts, Google Shopping Graph.

**Embedded Checkout Protocol (ECP)**
A sub-protocol within UCP for handling escalations that require human involvement during an otherwise agent-driven checkout. ECP uses JSON-RPC 2.0 bidirectional channels between the agent and merchant, with PCIv4 sandboxing compliance for payment data. When a Checkout Session enters the requires_escalation state, ECP provides a continue_url that hands the user off to the merchant's interface for sensitive operations. See also: Checkout Session, UCP.

**Facilitator**
In the x402 protocol, an intermediary service that handles payment verification and settlement so sellers do not need to maintain blockchain infrastructure. Coinbase offers a hosted facilitator service with 1,000 free transactions per month. The Facilitator role lowers the barrier to accepting stablecoin payments, making x402 accessible to merchants who want machine-to-machine payment capabilities without managing crypto wallets or nodes. See also: x402.

**GEO (Generative Engine Optimization)**
The practice of optimizing content to be referenced and cited by AI-powered generative search engines such as Google AI Overviews, ChatGPT, Perplexity, and Gemini. GEO focuses on making content the authoritative source that AI models draw from when generating answers. Gartner predicts a 25 percent drop in traditional search engine volume by 2026. Key tactics include structured data, authoritative content, clear entity definitions, and citation-worthy formatting. Tools emerging in 2026 include Scrunch, Adobe LLM Optimizer, AthenaHQ, Bluefish, Peec AI, Profound, and Semrush AI Visibility Toolkit. For merchants, GEO determines whether your products and brand appear in AI-generated shopping recommendations. See also: AEO.

**Google Shopping Graph**
Google's comprehensive, real-time dataset of products, sellers, brands, reviews, and inventory information drawn from merchants, brands, and aggregators worldwide. The Shopping Graph powers product discovery across Google Search, Google Shopping, and Google AI Mode. In the context of agentic commerce, the Shopping Graph serves as one of the primary data sources that AI agents query when searching for products on behalf of users. Merchants feed into the Shopping Graph through Google Merchant Center, structured data markup, and UCP endpoints. Ensuring accurate, complete product data in the Shopping Graph is essential for visibility in agent-driven commerce. See also: UCP, GEO.

**Instant Checkout**
An ACP-powered feature launched on February 16, 2026 that lets ChatGPT users (Plus, Pro, and Free tiers in the US) purchase products directly inside the chat interface. The AI agent handles product discovery, comparison, and checkout within the conversation. Instant Checkout processes payments through Stripe, with OpenAI collecting a 4 percent platform fee. This feature is the primary consumer-facing implementation of ACP. See also: ACP, SharedPaymentToken.

**Intent Mandate**
A Verifiable Digital Credential in AP2 that is critical for "human-not-present" scenarios. An Intent Mandate captures the conditions under which an AI agent can make a purchase on the user's behalf when the user is not actively supervising the transaction. It is generated by the Shopping Agent based on the user's request and cryptographically signed by the user, typically using a hardware-backed key on their device. For example, "Buy me the cheapest flight to NYC next Friday under 300 dollars" would generate an Intent Mandate that authorizes the agent to execute the purchase autonomously within those parameters. See also: Cart Mandate, Payment Mandate, VDC.

**Know Your Agent (KYA)**
An emerging verification framework for establishing the identity, capabilities, and trustworthiness of AI agents participating in commerce transactions. KYA draws from Know Your Customer (KYC) principles in financial services and applies them to the agent ecosystem. In AP2, KYA is partially addressed through Verifiable Digital Credentials and Agent Cards that attest to an agent's identity and authorization scope. As agentic commerce scales, KYA will become essential for merchants to distinguish legitimate shopping agents from malicious bots, and for payment networks to assess transaction risk. See also: VDC, Agent Card, Trusted Agent Protocol.

**MCP (Model Context Protocol)**
An open protocol developed by Anthropic that standardizes how AI agents connect to external tools, APIs, data sources, and memory. MCP operates vertically -- it defines how a single agent accesses and interacts with capabilities, as opposed to A2A which defines how agents communicate with each other. OpenAI announced MCP support across all its products including the ChatGPT desktop app. In commerce, MCP enables agents to connect to merchant tools such as inventory systems, CRM platforms, and order management systems. MCP v2 updates were added in February 2026. See also: A2A, Storefront MCP.

**Merchant of Record**
The legal entity responsible for a transaction, including settlement, refunds, chargebacks, and regulatory compliance. In both UCP and ACP, the merchant remains the Merchant of Record -- neither Google, OpenAI, nor any protocol operator assumes this responsibility. This is a critical distinction from marketplace models where the platform may serve as Merchant of Record. Merchants adopting agentic commerce retain full liability and control over their transactions regardless of which protocol or agent surface initiates the sale. See also: Delegate Payment, Payment Handler.

**Merchant Profile**
A machine-readable document published by a merchant, typically at the .well-known/ucp endpoint, declaring everything an agent needs to know to transact: supported services, capabilities (catalog, checkout, returns), extensions (loyalty, subscriptions, fulfillment options), and payment handlers (Google Pay, Shop Pay, regional processors). In UCP, the merchant is treated as the source of truth. A well-structured Merchant Profile is the foundation of discoverability in decentralized agentic commerce. See also: .well-known/ucp, Capability Negotiation.

**Payment Handler**
In UCP, a declared payment processor that a merchant supports. Payment Handlers can include Google Pay, Shop Pay, Stripe, Adyen, PayPal, or regional processors. During Capability Negotiation, agents and merchants determine which Payment Handlers they mutually support, enabling dynamic payment method selection per transaction. This multi-processor flexibility is a key architectural difference between UCP (any handler) and ACP (Stripe only). See also: UCP, Capability Negotiation.

**Payment Mandate**
A Verifiable Digital Credential in AP2 that is shared with the payment network and card issuer to provide visibility into the agentic nature of a transaction. Unlike the Cart Mandate or Intent Mandate, the Payment Mandate does not authorize the purchase itself. Instead, it contextualizes the transaction for the financial system, helping networks and issuers build trust, assess risk, and apply appropriate fraud rules to agent-initiated transactions. Payment Mandates are essential for the payment industry's adoption of agentic commerce. See also: Cart Mandate, Intent Mandate, AP2.

**Seller Agent (Merchant Agent)**
The AI agent or system acting on behalf of a merchant or retailer in an agentic commerce transaction. A Seller Agent publishes capabilities, responds to agent queries, processes orders, and manages post-purchase flows. In UCP, this is the merchant's server exposing the .well-known/ucp endpoint. The Seller Agent is the merchant's automated counterpart to the Buyer Agent, handling the supply side of agent-to-agent commerce. See also: Buyer Agent, Merchant Profile.

**SharedPaymentToken (SPT)**
A concept within the ACP and Stripe ecosystem for facilitating agent-mediated payments. After a customer expresses intent to pay, the agent provisions a SharedPaymentToken -- a tokenized payment credential scoped to a specific amount and seller -- and shares it with the seller via a CompleteCheckoutRequest. This mechanism allows the agent to facilitate payment without directly handling sensitive card data. SharedPaymentTokens are single-use, time-bound, and amount-restricted. See also: ACP, Delegate Payment.

**Shopping Agent**
An AI agent that discovers, evaluates, negotiates, and purchases products on behalf of a user. Unlike a recommendation engine, a Shopping Agent can autonomously complete the entire transaction loop from understanding intent to executing payment. Shopping Agents are the core actors in agentic commerce, operating across surfaces including Google AI Mode, ChatGPT, Gemini, and Copilot. See also: Buyer Agent, Agentic Commerce.

**Storefront MCP**
A Model Context Protocol server implementation specifically designed for e-commerce, enabling AI agents to interact with a merchant's storefront programmatically. A Storefront MCP server exposes tools for product search, inventory lookup, cart management, and order placement. Because UCP supports MCP as a transport layer, merchants can serve both UCP-compliant agents and MCP-native agents through a single integration. Storefront MCP bridges the gap between Anthropic's tool-access protocol and commerce-specific workflows. See also: MCP, UCP.

**Trusted Agent Protocol (TAP)**
A framework for establishing chains of trust between AI agents, users, merchants, and payment providers in agentic commerce transactions. TAP ensures that every participant in a transaction can verify the identity and authorization of every other participant. In AP2, trust is engineered through cryptographically signed Verifiable Digital Credentials. TAP principles also inform Know Your Agent (KYA) verification and Agent Card authentication in A2A. As agentic commerce moves toward fully autonomous purchasing, TAP becomes the foundation that prevents fraud and enables accountability. See also: KYA, VDC, AP2.

**UCP (Universal Commerce Protocol)**
An open-source standard co-developed by Google and Shopify, announced at NRF in January 2026, that defines building blocks for agentic commerce from product discovery and buying to post-purchase experiences. UCP uses a three-layer architecture: Shopping Service (core primitives like checkout sessions and line items), Capabilities (functional areas like catalog and returns), and Extensions (domain-specific features like loyalty and subscriptions). UCP is decentralized and merchant-as-source-of-truth: merchants declare what they support, and agents discover and negotiate capabilities dynamically. It is endorsed by over 20 global partners including Shopify, Etsy, Wayfair, Target, Walmart, Adyen, American Express, Best Buy, and Stripe. UCP surfaces include Google Search AI Mode, Gemini, and any agent that implements the protocol. See also: ACP, .well-known/ucp, Capability Negotiation.

**Verifiable Digital Credential (VDC)**
Standardized data structures used in AP2 to convey trusted information between agents. VDCs are tamper-evident, non-disputable, portable, and cryptographically signed digital objects that serve as the building blocks of an agentic transaction. The three primary VDC types in AP2 are the Intent Mandate, Cart Mandate, and Payment Mandate. VDCs enable commerce in "human-not-present" scenarios by providing non-repudiable proof of user authorization. They are foundational to AP2's security model. See also: AP2, Intent Mandate, Cart Mandate, Payment Mandate.

**Verifiable Intent**
The concept that a user's purchasing intention can be captured, cryptographically signed, and verified by all parties in a transaction. Verifiable Intent is operationalized through AP2's Intent Mandate, which records the conditions under which an agent is authorized to act. This concept is critical for resolving disputes in agentic commerce: if a user claims they did not authorize a purchase, the Verifiable Intent provides non-repudiable evidence of the original instruction. See also: Intent Mandate, VDC.

**Virtual Try-On**
An AI-powered feature that allows consumers to visualize how products (typically apparel, accessories, or cosmetics) would look on them before purchasing. In the context of agentic commerce, Virtual Try-On capabilities can be exposed as UCP extensions, enabling shopping agents to offer try-on experiences as part of the discovery and evaluation process. Google has integrated Virtual Try-On into Google Shopping and AI Mode, making it accessible within agent-driven commerce flows. For merchants, supporting Virtual Try-On through structured product data (model images, size specifications) can improve conversion rates in agentic channels.

**x402**
An open payment protocol developed by Coinbase that revives the long-unused HTTP 402 Payment Required status code to enable instant, automatic stablecoin payments directly over HTTP. x402 is designed for machine-to-machine transactions where AI agents can pay for and access services autonomously. The flow works as follows: a client requests a resource, the server responds with 402 Payment Required plus payment details, the client creates a payment payload and resends the request with a payment signature header, and the server verifies payment and serves the resource. Settlement occurs via stablecoin payments on Base and Solana blockchains. The x402 Foundation was launched with support from Coinbase and Cloudflare. In the broader protocol stack, x402 provides a specific settlement mechanism while AP2 provides the trust framework. See also: Facilitator, AP2.

**/.well-known/ucp**
A standard JSON manifest endpoint located at /.well-known/ucp on a merchant's domain where businesses publish the services they support and corresponding capabilities. This endpoint allows agents to dynamically discover features, endpoints, payment configurations, and extensions without hard-coded integrations. It contains supported services, capabilities, extensions, payment handlers, and merchant metadata. The concept follows the same pattern as /.well-known/openid-configuration for OAuth or robots.txt for crawlers. Publishing a .well-known/ucp manifest is the first step for any merchant implementing UCP. See also: UCP, Merchant Profile, Capability Negotiation.

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## Protocol Comparison Matrix

The following table compares the major protocols shaping agentic commerce as of March 2026.

| | **UCP** | **ACP** | **AP2** | **x402** | **MCP** | **A2A** |
|---|---------|---------|---------|----------|---------|---------|
| **Created by** | Google + Shopify | OpenAI + Stripe | Google | Coinbase | Anthropic | Google |
| **Focus** | Full commerce lifecycle | Agent-led buying | Agent payments and trust | HTTP-native payments | Agent-to-tool connection | Agent-to-agent communication |
| **Architecture** | Decentralized | Platform-mediated | Decentralized | Decentralized | Vertical (agent to tools) | Horizontal (agent to agent) |
| **Discovery** | .well-known/ucp | OpenAI merchant portal | Agent Cards (A2A) | HTTP 402 response | Tool manifests | Agent Cards |
| **Payment model** | Any handler (negotiated) | Stripe exclusively | Any (VDC-based) | Stablecoins (USDC) | N/A | N/A |
| **Auth model** | Capability negotiation + signing keys | Platform API keys | VDCs + Mandates | Crypto signatures | Tool permissions | Agent Cards + JWS |
| **Platform fee** | None | 4% (OpenAI) | None | Facilitator-dependent | None | None |
| **Open source** | Yes | Yes (Apache 2.0) | Yes (Apache 2.0) | Yes | Yes | Yes |
| **Live surfaces** | Google AI Mode, Gemini | ChatGPT | In development | Base, Solana | Cross-platform | Cross-platform |
| **Geographic scope** | Global | US only (expanding) | Global | Global | Global | Global |
| **Key partners** | 20+ (Shopify, Etsy, Walmart, Target, Visa) | OpenAI, Stripe, select merchants | 60+ (Mastercard, Adyen, PayPal, Visa) | Coinbase, Cloudflare | OpenAI, broad ecosystem | 50+ (Salesforce, LangChain) |

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## Frequently Asked Questions

**What is the difference between UCP and ACP?**
UCP (Universal Commerce Protocol) and ACP (Agentic Commerce Protocol) are complementary, not competing. UCP is decentralized and merchant-hosted: merchants publish a .well-known/ucp manifest on their own domain, and any AI agent can discover and transact with them. ACP is platform-mediated: merchants submit product data to OpenAI, and ChatGPT surfaces products to users. UCP charges no platform fee and supports multiple payment processors; ACP charges a 4 percent fee and requires Stripe. UCP works across Google AI Mode, Gemini, and any open agent; ACP works within ChatGPT. Dual-protocol merchants report up to 40 percent more agentic traffic than single-protocol stores, so the recommended strategy is to implement both.

**What is the difference between GEO and AEO?**
GEO (Generative Engine Optimization) and AEO (Answer Engine Optimization) are largely synonymous terms used interchangeably in the industry. Both refer to optimizing content so that AI systems cite it when generating answers. The subtle distinction is that AEO emphasizes structured extraction in traditional search engines (featured snippets, voice search, zero-click results), while GEO emphasizes being cited by AI-native platforms (ChatGPT, Gemini, Perplexity). In practice, the same tactics -- structured data, authoritative content, clear definitions, and citation-worthy formatting -- serve both. Traditional SEO optimizes for search engine rankings; AEO and GEO optimize for AI-generated answers and citations.

**Do merchants need to support all six protocols?**
No. The six protocols (UCP, ACP, AP2, x402, MCP, A2A) operate at different layers and serve different purposes. Most merchants should start with UCP for broad agent discoverability, then add ACP for ChatGPT coverage. AP2 adds a trust and authorization layer on top of UCP for handling autonomous purchases. MCP and A2A are infrastructure protocols that agents use internally -- merchants interact with them indirectly through UCP. x402 is relevant only for merchants who want to accept stablecoin payments for machine-to-machine transactions. A practical starting point for most merchants is UCP plus ACP, which can be implemented in 10 to 20 hours combined.

**What are Mandates in AP2, and why do they matter?**
Mandates are Verifiable Digital Credentials (VDCs) in the Agent Payments Protocol that define what an AI agent is authorized to do on a user's behalf. There are three types. A Cart Mandate authorizes a specific purchase when the user is present and reviewing the cart. An Intent Mandate authorizes future purchases under specified conditions when the user will not be present (for example, "buy any flight under 300 dollars"). A Payment Mandate provides transaction context to payment networks and card issuers for risk assessment. Mandates matter because they solve the fundamental trust problem of agentic commerce: how do you prove a user authorized a purchase when no human was present at the time of the transaction? They are cryptographically signed and non-repudiable, which is essential for dispute resolution and fraud prevention.

**How does agentic commerce affect conversion rates?**
Early 2026 data shows that agentic commerce dramatically outperforms traditional channels. Agentic traffic converts at an average of 19.8 percent, compared to 2.8 percent for organic search and 1.2 percent for social media referrals. High-intent agentic traffic reaches 29.5 percent conversion. Cart abandonment drops from approximately 70 percent in traditional e-commerce to under 5 percent in agentic flows, because AI agents do not get distracted, do not abandon carts, and pre-qualify purchase intent before initiating a checkout session. One early adopter, Sierra Roast, reported a reduction in customer acquisition cost from 40 dollars to 4 dollars after implementing UCP.

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*This glossary is maintained as a living reference. Terms and definitions reflect the state of the agentic commerce ecosystem as of March 2026. For protocol specifications, see [ucp.dev](https://ucp.dev/), [ap2-protocol.org](https://ap2-protocol.org/), [x402.org](https://www.x402.org/), and the [ACP GitHub repository](https://github.com/agentic-commerce-protocol/agentic-commerce-protocol).*