What is Next.js?

Next.js is a React framework that provides everything you need to build production-ready web applications. While React is a library for building user interfaces, Next.js is a complete framework that handles routing, bundling, optimization, and deployment.

Key Features That Make Next.js Special

Multiple Rendering Methods:

• Static Site Generation (SSG) for lightning-fast sites
• Server-Side Rendering (SSR) for dynamic content
• Client-Side Rendering (CSR) when needed
• Incremental Static Regeneration (ISR) for the best of both worlds

Built-in Optimizations:

• Automatic code splitting
• Image optimization with next/image
• Font optimization
• Script optimization
• Bundle analyzer

Developer Experience:

• File-based routing (no need for routing libraries)
• API routes (build your backend in the same project)
• Built-in CSS and Sass support
• TypeScript support out of the box
• Hot reloading and fast refresh

Modern Features (Next.js 13+):

• App Router with nested layouts
• Server Components and Client Components
• Streaming and Suspense
• Middleware and Edge Runtime

Simple Example

Pages Router (Traditional):

// pages/index.js
export default function Home({ posts }) {
  return (
    <div>
      <h1>My Blog</h1>
      {posts.map(post => (
        <article key={post.id}>
          <h2>{post.title}</h2>
          <p>{post.excerpt}</p>
        </article>
      ))}
    </div>
  )
}

// This runs at build time
export async function getStaticProps() {
  const posts = await fetch('https://api.example.com/posts').then(r => r.json())
  return { props: { posts } }
}

App Router (Next.js 13+):

// app/page.js
export default async function Home() {
  const posts = await fetch('https://api.example.com/posts', {
    next: { revalidate: 3600 } // ISR: revalidate every hour
  }).then(r => r.json())
  
  return (
    <div>
      <h1>My Blog</h1>
      {posts.map(post => (
        <article key={post.id}>
          <h2>{post.title}</h2>
          <p>{post.excerpt}</p>
        </article>
      ))}
    </div>
  )
}