Next.js
Next.js App Router: Everything You Need to Know
Understand layouts, pages, server components, and routing in the modern Next.js App Router.
byte team··10 min read·Updated Jan 6, 2026
The App Router maps folders in app/ to routes. Files such as page.tsx, layout.tsx, and loading.tsx describe what each route renders.
Start with server components
Components are server components by default. They can read local files and fetch data without adding that code to the browser bundle.
Add client code deliberately
Use the 'use client' directive only for browser interactions such as state, event handlers, and effects.