App Router project structure Server Components Client Components with use client Nested layouts Route groups Dynamic route segments Catch-all route segments Loading UI with loading.tsx

Server-side data fetching fetch cache control Revalidation with next revalidate generateStaticParams generateMetadata Streaming with Suspense Error boundaries with error.tsx notFound and not-found.tsx

Route Handlers GET Route Handlers POST Server Actions Cookies API Headers API Redirects Middleware matcher Draft Mode

next/image optimization next/font next/link prefetching Environment variables Parallel routes Intercepting routes Metadata Open Graph images Cache tags and revalidateTag