The Shopify SEO and AI shopping glossary

The Shopify SEO vocabulary doubled in size between 2024 and 2026 — Shopify Catalog, agentic commerce, Knowledge Base, llms.txt, GEO, AEO, INP. Most of these didn't exist in their current form three years ago⁹. This page defines the 17 terms that materially change how a Shopify store shows up, including the theme and developer terms you meet as soon as you open the code: Liquid, the currency format, the API key. One sentence each, plain English, with a longer page for every one.

Below is the alphabetical index. Every term links to a longer page with the Shopify-specific detail: where the setting or file lives, which doc says so, and what to do when the default behaviour is wrong.

§ 01 How to read this

How to read this glossary

If you Googled a term ("what is GEO?", "what is Shopify Catalog?") and want a one-sentence answer before reading further, every entry below gives that on one line. Click through to the longer page for the install-level treatment.

Where a term has rebranded or evolved — INP replacing FID as a Core Web Vital⁸, GEO emerging as the umbrella discipline that contains AEO — both terms are listed and the longer page documents the change with dates. Where Shopify has its own term for something other platforms call by a different name (Shopify Catalog, Knowledge Base, robots.txt.liquid), the longer page links the Shopify Help Center doc that names the feature first³.

§ 02 A · B · C

A · B · C

A–C covers AEO and agentic commerce on the AI-search side, the API key and currency format on the developer side, and the canonical tag Shopify auto-generates on every page.

Agentic commerce: Agentic commerce is the pattern in which an AI agent helps a shopper discover, compare, and purchase products inside the AI conversation itself, rather than directing the shopper to a storefront. Shopify's own definition, published April 2026.
Answer Engine Optimization: Answer Engine Optimization (AEO) is the practice of structuring content so AI answer engines — ChatGPT, Perplexity, Claude, Gemini, Google AI Overviews — extract and quote your page as the answer to a user's question.
API key: A Shopify API key is an app's client ID. It identifies the app, while Admin API calls are authorized by an access token. Since 1 January 2026, new custom apps are created in the Dev Dashboard, not the Shopify admin.
Canonical tag: A canonical tag is the rel=canonical link element that tells search engines which URL is the preferred address for a piece of content when duplicates or near-duplicates exist. Shopify themes auto-generate canonicals on every page.
Currency format: Shopify's currency format (the money format) is the store setting that controls how prices print: symbol, separators and decimals. Liquid's money filters read it, and it only applies to the store's base currency.

§ 03 D · E · F · G · H

D · E · F · G · H

Generative Engine Optimization and GTIN. The first is the umbrella discipline for AI-search work; the second is the product identifier Shopify stores in the Barcode field, and it gets mis-defined on generic SEO blogs.

Generative Engine Optimization: Generative Engine Optimization (GEO) is the broader discipline of getting cited inside generative-AI responses across every engine — Answer Engine Optimization plus retrieval-graph, entity, and citation-hygiene work.
GTIN for Shopify products: GTIN (Global Trade Item Number) is the GS1 standard product identifier — UPC, EAN, ISBN, and JAN are all GTINs. Shopify exposes it through the product Barcode field.

§ 04 I · J · K · L

I · J · K · L

INP, JSON-LD, LCP, Liquid, llms.txt. I–L holds two Core Web Vitals, the schema syntax Google prefers, the template language every Shopify theme is written in, and Jeremy Howard's publisher manifest.

Interaction to Next Paint: Interaction to Next Paint (INP) is the latency between a user interaction (click, tap, key) and the next paint. INP replaced First Input Delay as a Core Web Vital on 12 March 2024. The 'good' threshold is 200 ms or less.
JSON-LD: JSON-LD is the JSON-based syntax Google recommends for emitting Schema.org structured data, written inside a <script type="application/ld+json"> tag in the page's HTML.
Largest Contentful Paint: Largest Contentful Paint (LCP) is the time from page navigation to the render of the largest visible image, text block, or video. The Core Web Vital threshold for 'good' is 2.5 seconds or less.
Liquid: Liquid is the open-source template language Shopify created and every Shopify theme is written in. Objects output store data, tags add logic, and filters change the output. The deep page includes a cheat sheet.
llms.txt: llms.txt is a proposed plain-text manifest at the root of a site (e.g. example.com/llms.txt) that lists the URLs an LLM should prefer when answering questions about the site. Proposed by Jeremy Howard, September 2024.

§ 05 M through Z

M through Z

M–Z holds the Shopify-native files and features, filed under the names merchants search: robots.txt.liquid, Shopify Catalog, Shopify duplicate content, the Shopify Knowledge Base app, and structured data.

robots.txt.liquid: robots.txt.liquid is the Shopify theme template that renders the store's /robots.txt file. It is the only way to customise robots rules on a Shopify store, and Shopify Support warns it can take down all traffic if edited incorrectly.
Shopify Catalog: Shopify Catalog is a structured source of product information gathered from eligible products that are sold by stores on Shopify. AI channels — ChatGPT, Copilot, Gemini, Perplexity, Shop — read Catalog data to support product discovery and to display product details, comparisons, and recommendations.
Shopify duplicate content: Duplicate content is the same or near-identical content reachable at more than one URL. On Shopify, the classic case is products appearing at both /products/{handle} and /collections/{collection}/products/{handle}.
Shopify Knowledge Base app: Shopify Knowledge Base is a free app, built by Shopify, where merchants view and edit the FAQs AI shopping agents use to answer buyer questions about a store. Launched 16 May 2025; available on every Shopify plan.
Structured data: Structured data is machine-readable markup that describes the meaning of page content (a product, a person, an article) in a standard vocabulary like Schema.org. Shopify themes auto-emit Product schema.

§ 06 Where each term lives

Where each term lives in the rest of the site

A glossary entry is rarely the whole answer. Below is the routing map: where each cluster of terms goes for the install-level treatment. The 17 deep pages cover the long-form definition; the pillars cover the install; the FAQ hub covers the question-shaped variant.

AI-shopping vocabulary (AEO, GEO, agentic commerce, Shopify Catalog, Knowledge Base, llms.txt) routes into Shopify AI Shopping & GEO.
Schema and structured data (JSON-LD, structured data, GTIN) routes into Shopify Schema & Product Data.
Core Web Vitals and performance (LCP, INP) routes into Site speed on Shopify.
Classical Shopify SEO mechanics (canonical tag, duplicate content, robots.txt.liquid) routes into Shopify SEO Mechanics.
Theme and developer terms (Liquid, currency format, API key) have no pillar of their own. Their glossary pages are the reference, and each one links into the theme-code guides, starting with custom JSON-LD via theme.liquid.

The newer the term, the more Shopify-specific the install. Older mechanics like the canonical tag and structured data are about the same across every platform; the 2024–2026 vocabulary each requires an explicit Shopify-side step (Catalog needs plan + product eligibility, llms.txt has no native Shopify support, INP needs theme-level interaction tuning). The longer pages spend more time on the AI-era terms because that's where the platform-specific work lives. The Catalog gate in particular is walked step by step at Shopify Catalog eligibility.