Next.js 16 App Router: The Complete Guide for 2026

What Is the App Router? The App Router, introduced in Next.js 13 and now the default in Next.js 16, is a file-system based router built on top of React Server Components. It lives in the app/\ directory and replaces the older pages/\ router as the recommended approach for all new projects. If you're still building with pages/\ , the App Router isn't just a new feature — it's a fundamentally different mental model. Understanding it properly will make you a significantly more effective Next.js dev