BeginnerNext.jsApp Router
Next.js App Router Foundations
The mental model that makes a Next.js codebase legible: how folders become routes, how layouts and pages divide the work, and how route handlers give you a server boundary for data and APIs. Foundational and hands-on.
3 lessons · ~1 hour
1. Foundations
Folders are routes
Read an App Router tree like a map — folders are segments, special files are the UI for each one.
Layouts vs. pages
Layouts are the frame that stays; pages are the painting that changes. Put durable chrome in the right place.
Route handlers & data
Add a server endpoint with a route handler, and decide what to cache vs. keep fresh.