Next.js: The Complete Guide

Next.js is a React framework for building full-stack web applications. You use React Components to build user interfaces, and Next.js for additional features and optimizations.

1. Key Features

🚀 Routing

Next.js uses a file-system based router.

App Router (Recommended): Uses the app directory. Supports Shared Layouts, Nested Routing, Loading States, and Error Handling.
Pages Router: The legacy router using the pages directory.

🌓 Rendering Strategies

Server-Side Rendering (SSR): Generates HTML on each request. Use getServerSideProps (Pages Router) or Server Components (App Router).
Static Site Generation (SSG): Generates HTML at build time. High performance, great for SEO.
Incremental Static Regeneration (ISR): Allows you to update static content after you've built your site, without needing to rebuild the entire site.
Client-Side Rendering (CSR): Standard React rendering in the browser.

⚛️ Server vs. Client Components

In the App Router:

Server Components (Default): Render on the server. They don't send JS to the client, reducing bundle size. Good for data fetching and SEO.
Client Components: Use the 'use client' directive. Necessary for interactivity (hooks like useState, useEffect) and browser APIs.

📥 Data Fetching

Next.js extends the native fetch API to provide per-request caching and revalidation.

Server-side fetching: Fetch data directly in Server Components using async/await.
Route Handlers: Create custom request handlers for your API (like GET, POST).

🎨 Styling

CSS Modules: Locally scoped CSS to avoid naming conflicts.
Tailwind CSS: Built-in support for the utility-first CSS framework.
CSS-in-JS: Support for libraries like styled-components or emotion.

⚡ Optimizations

Image Component (next/image): Automatic image optimization, lazy loading, and WebP support.
Font Optimization (next/font): Automatically optimizes and loads custom fonts.
Script Optimization (next/script): Controls how third-party scripts are loaded.

2. Project Structure (App Router)

├── app/
│   ├── layout.tsx      # Root Layout (required)
│   ├── page.tsx        # Homepage
│   ├── globals.css     # Global styles
│   └── (routes)/       # Folder-based routing
│       ├── about/
│       │   └── page.tsx
│       └── blog/
│           ├── page.tsx
│           └── [slug]/ # Dynamic routes
│               └── page.tsx
├── public/             # Static assets (images, icons)
├── next.config.js      # Configuration for Next.js
├── package.json        # Dependencies and scripts
└── tsconfig.json       # TypeScript configuration

3. Deployment

The creators of Next.js, Vercel, provide the easiest way to deploy Next.js applications with zero configuration. It can also be self-hosted using Node.js or Docker.

Generated by Gemini CLI on 2026-06-05

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