Next.js App Router

Next.js App Router is the modern routing system introduced in Next.js 13 that represents a fundamental shift in how Next.js applications are structured and built. The App Router uses a new file-system based routing convention with the app directory, replacing the previous pages directory approach. It introduces React Server Components by default, allowing components to render on the server without sending JavaScript to the client. The App Router provides layouts, loading states, error boundaries, and streaming server rendering for improved performance and user experience. It supports advanced features like parallel routes, intercepting routes, and route groups for sophisticated application architectures. The new routing system enables fine-grained data fetching at the component level with automatic deduplication and caching. It includes built-in support for TypeScript, improved SEO capabilities, and better integration with React's concurrent features. While the Pages Router remains supported, the App Router represents the future direction of Next.js development.