Every conversation about Shopify design leans on the same twenty words, and most explanations of them are written for developers. Here they are in plain English, two or three sentences each, in roughly the order you will meet them.
The foundations
Theme. The complete package that controls how your Shopify store looks and behaves: every layout, template, style and script. Your products and orders live in Shopify itself; the theme is the presentation layer you can swap, edit or replace without touching your data.
Liquid. Shopify's template language, the code themes are written in. It mixes HTML with placeholders like {{ product.title }} that Shopify fills with your store's real data when the page renders.
Online Store 2.0 (OS 2.0). The current theme architecture, introduced in 2021. Its defining feature: sections work on every page, not just the homepage, and apps can inject blocks without editing theme code.
Theme editor (customizer). The visual editing screen in your Shopify admin (Online Store, then Customize). It lets you rearrange sections and change their settings without writing code. What you can change there is decided by the theme's schemas.
Dawn. Shopify's free default theme and the reference implementation of OS 2.0. Most free themes are built on its patterns, which is why so many stores look related out of the box.
The building blocks
Section. A self-contained page component: a hero banner, a product grid, a testimonial row. Sections can be added, removed and reordered per page in the theme editor, and each carries its own settings.
Block. A repeatable element inside a section. In a testimonials section, each testimonial is a block; merchants add and remove them in the editor without touching layout code.
Schema. The JSON block at the bottom of a section file that declares its editable settings: which texts, images, colors and toggles appear in the theme editor. No schema entry, no knob for the merchant. (You can build one in seconds with our free schema generator.)
Template. The file that decides which sections make up a page type: product pages, collection pages, the homepage. In OS 2.0 these are JSON files listing sections in order.
Snippet. A reusable fragment of Liquid included by other files: a price display, an icon, a card. Change the snippet once and every place that uses it updates.
App blocks / app embeds. The two OS 2.0 ways apps add functionality to a theme: blocks appear as draggable elements in the editor, embeds run globally (a chat widget, a tracking pixel) and toggle on or off in theme settings.
The data layer
Metafields. Custom data fields you attach to products, collections or pages: an ingredients list, a size chart, a care guide. Themes read them to display information Shopify has no built-in field for.
Settings data (settings_data.json). The file storing every choice made in the theme editor: colors, fonts, section arrangements. It is why two stores on the same theme can look completely different.
Locales. The translation files of a theme. Every piece of interface text ("Add to cart", "Sold out") lives there, which is what makes themes translatable without code edits.
Judging and choosing themes
Theme Store theme. A theme sold through Shopify's official marketplace, which enforces performance and quality standards. Themes sold outside it (or generated custom) can do things the guidelines forbid, for better and worse.
Custom theme. A theme built for one brand instead of bought as a template: traditionally weeks of agency work, now also the output of AI generation. The practical test of "custom": whether the layout was designed around your brand, or your brand poured into someone else's layout.
Theme detector. A tool that reads a store's public page data to report which theme it runs. Useful before borrowing ideas: it tells you whether the design you admire is a theme you could buy or a custom build you would need to rebuild. (Try ours free: Shopify theme detector.)
Headless commerce. Running a custom front end (often React) on top of Shopify's backend through APIs, instead of using a theme. Maximum flexibility, developer-team price tag; for most merchants a well-built theme is the right trade.
The AI layer
AI theme generation. Producing a theme's actual code from a description or reference design, sections, schemas and templates included, rather than configuring a pre-made template. The output installs and edits like any theme. (This is what Clyro does.)
Shopify Magic and Sidekick. Shopify's built-in AI: Magic generates content (descriptions, emails, image edits), Sidekick assists with admin tasks in chat. Neither writes theme code, which is the common misconception; the design layer needs a dedicated tool.
Keep reading: what a Shopify theme generator actually outputs and the best Shopify themes this year.