The Next.js App Router, introduced in Next.js 13, represents a significant shift in how you build web applications with Next.js. It's built on React Server Components, offering new capabilities for data fetching, caching, and rendering.

Key Features

Server Components: Render on the server, send only the necessary HTML and CSS to the client, leading to smaller JavaScript bundles.
Layouts: Share UI across multiple routes without re-rendering, improving performance.
Nested Routing: Create complex UI hierarchies that map directly to your file system.
Streaming: Render parts of your UI as they become ready, improving perceived performance.

Benefits

The App Router aims to provide a more performant and developer-friendly experience. By leveraging server components, you can keep more logic on the server, reducing the amount of JavaScript sent to the client. This leads to faster initial page loads and better Core Web Vitals.

Getting Started

To start with the App Router, ensure you're using Next.js 13 or later. New projects will use it by default. For existing projects, you can gradually migrate components and routes.

The routing paradigm shifts from a 'pages' directory to an 'app' directory, where each folder represents a segment of the URL, and 'page.js' defines the UI for that segment.