A2A (Agent-to-Agent Protocol)
An open protocol for communication between AI agents.
A2A lets agents discover one another, exchange messages and coordinate tasks. It focuses on agent collaboration rather than access to individual tools.
AI commerce glossary
39 terms, in plain English.
Find the meaning, then the next step.
A
ACP (Agentic Commerce Protocol)
An open specification for purchases involving buyers, AI agents and sellers.
ACP defines a programmatic exchange for commerce, including checkout. Implementation requirements and available purchasing experiences depend on the participating platforms and merchants.
AEO (Answer Engine Optimization)
Making content easier to find and use in AI-generated answers.
AEO describes writing and structuring useful answers so an answer engine can understand and reference them. Clear explanations and accurate structured data can help; they do not guarantee a citation.
Agent Ready Score
AgentReadyHQ’s rule-based diagnostic score.
A 0-100 summary of applicable checks from a sampled public-site crawl. It highlights technical opportunities and crawl limitations; it does not measure actual rankings, AI recommendations or sales.
Agentic Commerce
Shopping tasks carried out by AI agents on a customer’s behalf.
An agent may help someone discover products, compare options or complete a purchase. How much it can do depends on the shopping service, the customer’s authorization and the merchant’s integration. Product discovery and an agent-enabled checkout are separate capabilities.
AI Mode (Google)
Google Search’s conversational experience for exploring questions and products.
AI Mode can help shoppers research products and compare options within Google Search. Product data, normal search eligibility and supported commerce integrations serve different purposes. A listing or UCP implementation does not guarantee a recommendation or access to every checkout feature.
AI Shopping Agent
An AI system that helps a shopper research products or carry out purchasing tasks.
A shopping agent can interpret a request, find relevant products and compare details such as price or availability. Some services support purchasing through participating merchants; others send shoppers to a merchant’s site. Capabilities, supported regions and authorization requirements vary.
B
BuyAction Schema
Schema.org markup describing the action of buying something.
BuyAction is a Schema.org action type for a purchase involving an agent, an item and a seller. Describing a potential action does not implement payments or enroll a store in an AI shopping service. Use markup that accurately describes a real action, and follow the receiving platform’s requirements.
C
ChatGPT Shopping
Product discovery and comparison within ChatGPT.
Shoppers can explore products in ChatGPT using information from the web and merchant feeds. OpenAI is moving away from a standalone Instant Checkout experience and prioritizing merchant-owned websites and apps for purchases. A product feed can improve control over catalog information; neither a feed nor a Stripe integration is a universal requirement to appear.
Conversion Rate (AI-Referred)
The share of visits attributed to AI referrals that result in a purchase.
Calculate this rate by dividing attributed purchases by attributed visits, using a consistent period and attribution method. Analytics may miss or classify some AI referrals differently. Compare your own channels and cohorts rather than treating an industry average as a forecast for your store.
Crawlability (AI)
Whether a crawler can access and retrieve useful content from your site.
Robots rules, authentication, network access and page rendering can affect what a crawler retrieves. Different bots have different purposes. For example, OpenAI’s OAI-SearchBot supports search, while GPTBot is used for content that may be used in model training. Allowing a training crawler is not a prerequisite for appearing in that service’s search results.
D
Data Feed
A structured set of product information shared with a shopping platform.
A product feed can include titles, descriptions, prices, availability, images and identifiers. Platforms accept different formats, fields and delivery methods. Keep the data accurate and current, and follow the destination’s specification; supplying a feed does not guarantee placement or recommendations.
Discoverability (AI)
How readily an AI-powered service can find and surface your products or content.
Discoverability can be affected by access to your pages, product information, relevance and the service’s own selection systems. Helpful technical signals do not establish a measurable probability of being recommended. Check actual referrals and platform reporting alongside any diagnostic findings.
E
EAN (European Article Number)
A product identifier commonly referring to GTIN-13.
EAN-13 encodes a 13-digit Global Trade Item Number, widely used in retail. UPC and EAN are related formats within the GS1 identification system. Use the identifier assigned to the actual product, preserving leading zeroes where the receiving platform requires them.
F
Feed Management
Maintaining and distributing product data for different shopping channels.
Feed management includes collecting catalog information, mapping fields to each destination and keeping price, stock and identifiers up to date. Validation and monitoring can catch inconsistencies. Each platform sets its own accepted fields and participation requirements.
First-Party Data
Information your business collects directly through its own operations and relationships.
This can include catalog details, inventory, orders and customer interactions. Accurate product information is useful for customers and systems that read your site. Customer information is a separate concern: publishing a product feed does not mean publishing private customer data.
G
GEO (Generative Engine Optimization)
Practices intended to help generative AI systems understand and reference content.
GEO is a term used for improving content’s usefulness in AI-generated responses. It overlaps with SEO and AEO, and its meaning varies across the industry. Clear, relevant information can support discovery, but no markup or writing technique guarantees a citation.
Google Merchant Center
Google’s platform for managing product information and shopping programs.
Merchant Center lets businesses submit and manage product data, check product status and participate in eligible Google shopping programs. Requirements vary by program, country and product. Maintaining a feed is distinct from integrating a direct checkout or meeting eligibility for a particular AI experience.
GTIN (Global Trade Item Number)
A GS1 identifier used to distinguish a trade item across businesses and systems.
GTINs can have 8, 12, 13 or 14 digits. UPC and EAN are common forms. Product identifiers help platforms match the same item across listings. Use a valid identifier assigned to the product; do not invent one, and check the destination’s rules for products without an assigned GTIN.
I
Instant Checkout
The name used for ChatGPT’s earlier standalone in-chat purchase experience.
OpenAI introduced Instant Checkout as an experience for buying from participating merchants through ChatGPT. Its current merchant guidance says it is moving away from standalone Instant Checkout toward merchant-owned checkout. Check current documentation before following older integration guides; there is no universal commission rate implied by the ACP specification.
ISBN (International Standard Book Number)
An identifier for a specific book edition and format.
New ISBNs have used 13 digits since 2007; older 10-digit ISBNs also exist. An ISBN identifies a particular publication and edition, helping catalogs distinguish it from other books and formats. Supply the correct assigned number when a shopping platform requests it.
J
JSON-LD (JavaScript Object Notation for Linked Data)
A JSON-based format for publishing linked structured data.
JSON-LD can express Schema.org descriptions in a script element on a web page. Google recommends it for supported structured-data features. Keep the markup consistent with visible content and the feature’s documentation; the format itself does not guarantee rich results or AI recommendations.
L
LLMs.txt
A proposal for giving agents a concise Markdown guide to a website.
An llms.txt file can provide context, guidance and links to information in an agent-friendly format. It is not a crawler permission file like robots.txt. Publishing one does not guarantee indexing, and Google does not require special AI text files for its Search AI features.
M
MCP (Model Context Protocol)
An open standard for connecting AI applications to external data, tools and workflows.
MCP provides a common interface through which an application can access tools or contextual information exposed by a server. A merchant integration might expose product lookup or inventory tools. Access controls and supported operations still depend on the implementation; MCP alone does not authorize a purchase or provide a checkout.
Merchant Center
A common shorthand for Google Merchant Center.
See Google Merchant Center for how businesses manage product information and participate in eligible Google shopping programs.
Multimodal Search
Search that can combine input such as text, images or voice.
A shopper might use a product photo and a written request to look for a similar item. Good images and accurate descriptive information help people and systems understand a product. Available input types and shopping features depend on the service; they do not establish a universal conversion uplift.
O
Offer Schema
Schema.org markup describing commercial details such as price and availability.
An Offer can describe a seller’s price, currency, availability and other conditions for an item. It is often associated with a Product. Keep those details aligned with the visible page and actual offer, and follow the platform’s supported structured-data requirements.
P
Perplexity Shopping
Product research and shopping features within Perplexity.
Perplexity can help users discover and compare products with supporting information. It has also offered purchasing experiences for selected products and merchants. Availability and payment options vary; do not assume that every product supports an in-app purchase or that one fee policy applies to every integration.
Product Feed
Another name for a data feed containing product information.
A product feed shares structured catalog data with a destination such as a shopping service. See Data Feed and Feed Management for the information it can contain and the need to follow each destination’s specification.
Product Schema
Schema.org markup describing a product and its attributes.
Product markup can describe a name, image, brand, identifiers and other product details. Related Offer markup can describe commercial terms. Accurate structured data can help a receiving system interpret the page; supported properties and eligibility depend on the feature, and a valid record does not guarantee display.
R
Rich Results
Search results with additional supported information, such as product details.
Search engines may use eligible structured data to show enhanced information such as prices, availability or ratings. Valid markup is only one requirement, and Google does not guarantee a rich result for every eligible page. Rich results and placement in an AI-generated answer are different outcomes.
Robots.txt
A file that gives supported crawlers instructions about access to a site.
Robots rules apply to particular user agents and paths. Decide separately which uses you want to allow: OAI-SearchBot supports ChatGPT search, while GPTBot relates to potential model training. Google-Extended controls certain AI uses and does not control inclusion in Google Search. Robots.txt is not authentication and does not force every agent to comply.
S
Schema Markup
A vocabulary for describing page content in structured data.
Schema.org provides types and properties for describing products, offers, organizations and other entities. Publish accurate descriptions that match the visible page, using a format such as JSON-LD. Check the receiving platform’s supported features; extra markup does not guarantee indexing, a rich result or an AI citation.
Structured Data
Information organized in a format that software can interpret consistently.
Examples include Schema.org markup, product feeds and structured API responses. Their usefulness depends on accurate values, clear meaning and the receiving system’s support. Structured data can describe your store, but it is not a promise that an AI service will recommend it.
T
Transactability
Whether a particular system can complete a purchase through a supported integration.
This depends on the checkout interface, authorization, payment handling and the merchant and platform’s supported capabilities. Product discovery and transaction execution are separate. A commerce protocol or BuyAction markup alone does not establish that an AI agent can buy from your store.
U
UCP (Universal Commerce Protocol)
An open standard for connecting commerce systems and consumer experiences.
UCP defines interfaces for commerce capabilities and supports integrations with Google’s AI shopping surfaces. Merchants remain responsible for the purchase and must meet the relevant integration and participation requirements. Adopting the standard does not guarantee admission, a particular fee or visibility in every AI service.
UPC (Universal Product Code)
A product identifier commonly referring to GTIN-12.
The 12-digit UPC is widely used in North American retail and is commonly encoded in a barcode. It belongs to the GTIN identification system. Submit the identifier assigned to the specific product, rather than an internal SKU or a made-up number, where the destination asks for it.
W
Waiting Tax
An AgentReadyHQ metaphor for the potential cost of postponing useful improvements.
Waiting Tax is a planning metaphor, not a measured fee or an established AI ranking factor. Delaying an improvement can mean missed opportunities, but this glossary does not claim that AI agents assign a hidden trust score or that early adoption guarantees future placement.
Z
Zero-Click Search
A search interaction that ends without a click to an external website.
A person may get enough information from a search result or AI answer to stop there, refine the query or take another action. The rate depends on the study, audience and measurement method. Clear content is useful, but a zero-click interaction does not by itself demonstrate a lost or completed sale.
Why this glossary exists
AI commerce has plenty of acronyms. This is a reference for understanding them, with plain-English definitions and guides you can use when you need more detail.
Sources and updates
Definitions reviewed October 25, 2026. Features and participation requirements can change; check the relevant documentation before implementing an integration.
- A2A protocol and MCP documentation
- ACP specification and current ChatGPT merchant guidance
- Google UCP integration and Merchant Center product data
- Google Search AI guidance and OpenAI crawler purposes
- GS1 product identifiers and International ISBN Agency
- Schema.org BuyAction, structured data guidance and the llms.txt proposal
- Perplexity shopping announcement; available experiences vary.
The Agent Ready Score describes AgentReadyHQ’s checks on sampled public pages. It is not evidence of actual AI recommendations or sales. “Waiting Tax” is our planning metaphor, not a measured ranking factor.
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