What are the key features of Next.js?

Next.js bundles a set of features that would otherwise require stitching together multiple libraries. The headline ones:

• Hybrid rendering — every route can be statically generated, server-rendered, streamed, or rendered entirely on the client. Pick the right strategy per page instead of committing to one for the whole app.

• App Router with Server Components — the modern routing system uses React Server Components by default. Components can fetch data directly on the server, no API endpoint needed, and only client-needed code ships to the browser.

• File-system routing — folders inside app/ or pages/ become URLs. Special files like layout.tsx, loading.tsx, error.tsx, and not-found.tsx handle shared UI states declaratively.

• Server Actions — call server functions directly from forms or client components, no manual fetch wiring. Mutations get progressive enhancement for free.

• API routes / Route Handlers — backend endpoints live alongside frontend code, deployed as serverless functions on Vercel or your platform.

• Middleware — runs at the edge before requests reach a route. Used for auth checks, geo-routing, A/B tests, and rewrites.

• Built-in optimizations — automatic code splitting, prefetching links, the next/image component for responsive images, next/font for self-hosted fonts with no layout shift, and next/script for tag management.

• Caching layers — request memoization, the Data Cache, the Full Route Cache, and the Router Cache work together to keep pages fast without manual cache management.

• Incremental Static Regeneration (ISR) — static pages can revalidate on demand or on a schedule, combining the speed of static with the freshness of dynamic.

• TypeScript and ESLint built in — projects scaffold with strict type checking and linting configured.

• Turbopack — the new Rust-based bundler offers dramatically faster dev startup and HMR.

• Internationalization — built-in routing for locales, automatic language detection, and translated metadata.