# AEO and Agentic Commerce Glossary: 39 Terms > Plain definitions of 39 AEO and agentic commerce terms: AI crawlers, llms.txt, schema, ACP, UCP, AP2, MCP and AI visibility metrics. One line each. Source: https://angeo.dev/glossary/ Updated: 2026-09-29 Glossary # AEO and Agentic Commerce Glossary: 39 Terms **Plain definitions of the 39 terms you meet when making a store visible and usable for AI systems** - from GPTBot and llms.txt to UCP, AP2 and AI share of voice. One line each, with a link to the full page. **In one sentence** Every AEO and agentic commerce term on one page, one line each. **Sections:** Basics - Crawlers and access - Content for AI - Structured data - Agentic commerce - Measurement Every term links to its own page with the full definition, examples, sources and a verification date. Start with the [Magento AEO checklist](https://angeo.dev/magento-aeo-checklist/) if you want the order of work rather than the words. ## Basics [AEO (Answer Engine Optimization)](https://angeo.dev/magento-aeo-definition/) Making a store readable and usable for AI assistants such as ChatGPT, Claude, Perplexity and Gemini. [GEO (Generative Engine Optimization)](https://angeo.dev/magento-geo-agency/) The same work under another name: being included and cited in AI-generated answers. [LLMO (LLM Optimization)](https://angeo.dev/magento-llmo/) A third name for it, focused on how language models ingest a catalogue. [SEO vs GEO vs AEO](https://angeo.dev/seo-vs-geo-vs-aeo-practical-differences-for-e-commerce/) How the three disciplines differ in practice. [AI Commerce Visibility](https://angeo.dev/ai-commerce-visibility-definition/) Whether AI systems discover, trust and select a store for a recommendation. [AI Commerce Stack](https://angeo.dev/ai-commerce-stack-definition/) The five layers from structured data up to an AI-completed purchase. [AEO score](https://angeo.dev/aeo-score-definition/) A weighted 0-100 score of 20 signals: how ready a store is for AI systems. ## Crawlers and access [GPTBot vs OAI-SearchBot](https://angeo.dev/gptbot-vs-oai-searchbot/) OpenAI's training crawler and its search crawler: two jobs, two robots.txt rules. [Google-Extended](https://angeo.dev/google-extended-definition/) A robots.txt token for Gemini training and grounding. Not a crawler, and not an AI Overviews switch. [Web Bot Auth](https://angeo.dev/web-bot-auth-definition/) Bots prove who they are by signing their HTTP requests. [Content Signals and RSL](https://angeo.dev/content-signals-definition/) Machine-readable statements of what AI may do with content after fetching it. [AI crawlers reference](https://angeo.dev/docs/ai-crawlers/) Every AI user agent that matters for a store, with what blocking it does. ## Content for AI [llms.txt](https://angeo.dev/llms-txt-definition/) A short Markdown map of a site's key pages, served at the root. [llms-full.txt](https://angeo.dev/llms-full-txt-definition/) The full text of a site in one file. A convention, not part of the llms.txt spec. [Markdown mirror](https://angeo.dev/markdown-mirror-definition/) A clean Markdown copy of a page at the same URL with .md added (llms.txt v2). [llms.jsonl](https://angeo.dev/what-is-llms-jsonl-and-why-ecommerce-needs-it/) One JSON object per line, one per product: the catalogue in machine form. [AGENTS.md](https://angeo.dev/agents-md-definition/) Instructions for AI agents - for coding agents in a repository, for shopping agents on a store. ## Structured data [offers.availability](https://angeo.dev/offers-availability-definition/) The schema.org field that says whether a product can be bought right now. [Entity @id](https://angeo.dev/entity-id-definition/) The JSON-LD identifier that links organization, products and authors into one graph. [Return and shipping schema](https://angeo.dev/magento-return-policy-shipping-schema/) hasMerchantReturnPolicy, shippingDetails and hasShippingService, store-wide and per product. [FAQPage after May 2026](https://angeo.dev/faqpage-schema-after-2026/) What FAQ markup still does now that Google shows no FAQ rich results. ## Agentic commerce [Agentic commerce protocols](https://angeo.dev/agentic-commerce-protocol-definition/) ACP, UCP, AP2 and MCP side by side: who leads each and what it does. [ACP (Agentic Commerce Protocol)](https://angeo.dev/acp-definition/) OpenAI and Stripe's standard, now mainly the route to ChatGPT product discovery. [ACP product feed](https://angeo.dev/acp-product-feed-definition/) The catalogue file sent to OpenAI: nine required fields, one row per item. [UCP (Universal Commerce Protocol)](https://angeo.dev/ucp-definition/) Google's protocol for discovery and transaction, through a profile the store publishes. [/.well-known/ucp](https://angeo.dev/well-known-ucp-definition/) The UCP business profile: version, services, capabilities and public keys. [UCP authority binding](https://angeo.dev/ucp-authority-binding/) The check that a UCP schema URL is served from a host the namespace owner controls. [AP2 (Agent Payments Protocol)](https://angeo.dev/ap2-definition/) Signed mandates that prove a person approved an agent's purchase. [MCP for commerce](https://angeo.dev/mcp-commerce-definition/) Using the Model Context Protocol to expose catalogue and checkout as tools. [Agentic checkout](https://angeo.dev/agentic-checkout-definition/) A purchase completed by an AI agent while the store stays the seller. [Commerce agent](https://angeo.dev/commerce-agent-definition/) AI that acts on catalogue, cart and order data for shoppers or for staff. [Merchant of record](https://angeo.dev/merchant-of-record-definition/) The company that legally sells: payment, tax, refunds and the customer contract. [Shared Payment Token](https://angeo.dev/shared-payment-token-definition/) A single-use ACP payment token limited to one merchant, one checkout and one amount. [A2A Agent Card](https://angeo.dev/a2a-agent-card-definition/) The public profile of an A2A agent at /.well-known/agent-card.json. [MCP and agentic commerce glossary](https://angeo.dev/docs/mcp-glossary/) Implementation terms: JSON-RPC, Streamable HTTP, PKCE, RFC 8707, tool annotations. ## Measurement [AI share of voice](https://angeo.dev/ai-share-of-voice-definition/) How often assistants name your brand, compared with competitors, on fixed questions. [Grounding](https://angeo.dev/grounding-definition/) Whether an AI answer uses content fetched for the question or only training data. [GA4 AI Assistant channel](https://angeo.dev/ga4-ai-assistant-channel/) GA4's automatic channel for AI-referred visits since May 2026, and what it misses. [Measuring AI visibility](https://angeo.dev/measuring-ai-visibility/) Three layers: can AI read the store, does it name you, do people arrive and buy. ## Questions What does this glossary cover? 39 terms for making an online store readable and usable by AI systems: crawlers, llms.txt, structured data, agentic commerce protocols and measurement. Each links to a full definition. Where is the MCP implementation vocabulary? In the separate MCP and agentic commerce glossary under /docs/mcp-glossary/, which covers JSON-RPC, transports and OAuth terms. How current are the definitions? Each definition page states when it was last checked against its sources. Protocol versions and crawler names change, so check that date. ## Related - [Magento AEO checklist](https://angeo.dev/magento-aeo-checklist/) - [Magento 2 AEO guide](https://angeo.dev/magento-2-aeo-guide/) - [MCP and agentic commerce glossary](https://angeo.dev/docs/mcp-glossary/) - [Agentic commerce hub](https://angeo.dev/magento-agentic-commerce-hub/) ## Sources - [schema.org: DefinedTermSet](https://schema.org/DefinedTermSet) Index updated 29 September 2026. Each linked definition carries its own verification date.