Introduction

React (covered earlier) is a UI library, not a site builder — turning it into a fast content site takes routing, data fetching, and build tooling. Gatsby, released in 2015, packages all of that for content-heavy sites: blogs, docs, marketing pages, and portfolios. Its signature idea is a unified data layer: pull content from Markdown files, a headless CMS, or APIs into one GraphQL layer, then render it all as a static React site. It was the default React static-site choice for years, and its model still shapes how developers think about content sites.

The GraphQL data layer and the build

Gatsby's workflow has three stages:

Source — source plugins pull data in: Markdown files, WordPress, Contentful, or any API, all normalised into Gatsby's data layer.

Query — pages and components query that layer with GraphQL, asking for exactly the fields they need, at build time.

Build — Gatsby renders every page to static HTML with React hydration, so visitors get fast first loads and the site deploys to…