unified is an interface for processing text using syntax trees. It’s what powers remark (Markdown), retext (natural language), and rehype (HTML), and allows for processing between formats. unified enables new exciting projects like Gatsby to pull in Markdown, MDX to embed JSX, and Prettier to format it. It’s used in about 500k projects on GitHub and has about 25m downloads each month on npm: you’re probably using it. Some notable users are Node.js, Vercel, Netlify, GitHub, Mozilla, WordPress, Adobe, Facebook, Google, and many more.