.astro File — Astro Component

ASTRO files are components for the Astro web framework, a modern static site builder that pioneered the 'islands architecture' for building content-focused websites with minimal client-side JavaScript. Astro components use a file format that combines a frontmatter script section (delimited by ---) with an HTML template body. The frontmatter runs at build time (on the server), while the template produces static HTML by default. Astro's key innovation is that it ships zero JavaScript to the client by default — interactive components from any framework (React, Vue, Svelte, Solid) are hydrated on-demand using directives like client:load, client:visible, or client:idle, sending JavaScript only for interactive islands while the rest of the page remains static HTML. Astro supports file-based routing, Markdown and MDX content collections, view transitions, server-side rendering, and API endpoints. The framework has gained rapid adoption for content sites, documentation, blogs, marketing pages, and e-commerce storefronts where performance is critical. Astro's multi-framework support means teams can use their preferred UI framework for interactive components while benefiting from Astro's performance-first approach.