Introduction
BigCommerce is a hosted e-commerce platform: BigCommerce runs the servers, hosting, and checkout, and store owners customize on top of it rather than running their own infrastructure. There are three real paths for building the customer-facing storefront, and this course spends most of its time on the original one: Stencil, BigCommerce's theme engine, built around Handlebars, a general-purpose templating language (not BigCommerce-specific, unlike Shopify's Liquid).
Stencil themes
A Stencil theme is a folder of Handlebars template files, plus CSS/JavaScript, that BigCommerce renders using data it fetches for you at request time. Handlebars itself is intentionally simple — logic-light, meant mainly for output and basic loops/conditionals — which keeps templates predictable but pushes anything more complex out to JavaScript running in the browser.
<h2>{{product.title}}</h2>
<p>{{product.price.formatted.without_tax}}</p>
Two APIs, not one
BigCommerce splits its API surface in two: the Storefront API, a public, session-scoped API a storefront's own JavaScript calls directly from the browser (for things like updating the cart), and the Management API, an authenticated API for backend integrations, apps, and admin-level operations. Lesson 4 covers the distinction in more depth — for now, just know that "which API" is a question every BigCommerce integration has to answer early.
The other two paths: Catalyst and fully custom headless
A store isn't required to use Stencil at all. Catalyst is BigCommerce's own modern alternative — a full storefront framework built on Next.js and React, pre-wired to pull its data from the GraphQL Storefront API instead of Handlebars templates, and styled with an unopinionated Tailwind CSS setup rather than a fixed visual theme. Because it's an ordinary Next.js application under the hood, it can be deployed to any hosting provider that runs Node.js, not only BigCommerce's own infrastructure. Beyond Catalyst, a team can also go fully custom — building a frontend in whatever framework it already uses (Vue, Angular, plain JavaScript, a native mobile app) and talking to BigCommerce purely through its APIs, with no BigCommerce-provided framework in between at all. Lesson 13 covers Catalyst specifically, since it's the path BigCommerce actively develops and recommends when a team wants to leave Stencil behind.
Page Builder
One more term you'll encounter on the Stencil side: Page Builder is BigCommerce's drag-and-drop content editor, letting merchants arrange pre-built widgets without code (lesson 7).
Cornerstone and sample data
Cornerstone is BigCommerce's free, official reference theme — the Stencil equivalent of what Dawn is to Shopify. Most custom Stencil themes either fork Cornerstone directly or are built by studying how it structures its templates, partials, and schema. New development stores can also be seeded with realistic sample data (sample products, categories, and customers), which makes it possible to build and preview a theme meaningfully before a merchant has entered any real catalog data.