Atom — the smallest functional UI building block (a label, an input, a color token) that can't be broken down further without losing function. (Ch 3)
Molecule — a small, single-purpose group of atoms bonded together (e.g. a labeled search input); the first genuinely reusable, testable unit. (Ch 4)
Organism — a relatively complex, distinct interface section built from molecules and/or atoms (e.g. a page header, a product grid). (Ch 5)
Template — a full-page layout showing where organisms go, populated with placeholder content. (Ch 6)
Page — a specific instance of a template populated with real, representative content — where edge cases surface. (Ch 6)
Pattern library / style guide — the living, browsable collection of a system's components/patterns, ideally wired to real production code. (Ch 1, 8, 13)
Pattern Lab — the canonical tool from Atomic Design for building a nested, code-backed pattern library; conceptual ancestor of Storybook. (Ch 8)
Interface inventory — an audit exercise: screenshot every UI pattern in current production and lay them side by side to make inconsistency visible and build the case for a system. (Ch 9)
Design token — a named, platform-agnostic value (color, spacing, font size, shadow, duration) encoding a design decision once for reuse everywhere. (Ch 11)
Primitive token — a raw token value (e.g. blue-500 = #3B82F6), not tied to meaning or usage. (Ch 11)
Semantic token — a token that aliases a primitive to a meaning (e.g. color.action.primary = blue-500); the layer components should actually reference. (Ch 11)
DTCG (Design Tokens Community Group) format — the emerging W3C-adjacent standard JSON structure for portable, tool-agnostic token definitions. (Ch 11)
Style Dictionary — an open-source tool that transforms a single token source into per-platform output formats (CSS variables, native mobile, Tailwind config, etc.). (Ch 11)
Compound component — a component split into related sub-parts sharing implicit context (e.g. Tabs.Root/Tabs.List/Tabs.Trigger) instead of one component with a flat, growing prop list. (Ch 12)
asChild / render prop / slot — API patterns that let a consumer inject custom content or swap the rendered element without forking the component. (Ch 12)
Storybook / Ladle — component-explorer tools where each component gets isolated "stories"; the modern equivalent of a Pattern Lab-style living pattern library. (Ch 13)
Codemod — an automated script that mechanically rewrites old component usage into new usage across a codebase, used for large migrations. (Ch 16)
WCAG — Web Content Accessibility Guidelines; AA conformance is the de facto industry baseline most design systems target. (Ch 15)
Semver (semantic versioning) — patch/minor/major versioning applied to a component library's API contract, letting consumers judge upgrade risk from the version number. (Ch 14)