Ultimate Guide to React Server and Client Components

React 18 and Next.js 13+ introduced a powerful concept: Server Components and Client Components. If you’ve ever wondered when to use which, or why your button stops working when moved to the server, this guide is for you 🧠

In this post, I’ll break down what these components are, their differences, when to use them, and how they improve performance. Whether you're building a SaaS, a personal blog, or an e-commerce app, this will level up your React game 🚀

🔍 What Are Server Components?

Server Components are rendered on the server. They never reach the client — which means they don’t include JavaScript in the browser. That’s a big performance win!

Use them when:

• You don’t need interactivity
• You want to fetch data directly on the server
• You want to reduce bundle size

Example:

// app/page.js
export default async function HomePage() {
  const data = await getData();
  return <ArticleList data={data} />;
}

⚙️ What Are Client Components?

Client Components are interactive and rendered in the browser. Use them for anything dynamic like:

• Buttons
• Forms
• Event handlers

You declare them by adding 'use client' at the top:

"use client";

export default function LikeButton() {
  const [liked, setLiked] = useState(false);
  return (
    <button onClick={() => setLiked(!liked)}>{liked ? "❤️" : "🤍"}</button>
  );
}

🧠 When to Use Which?

🧪 Combining Both

You can combine both to create powerful apps. Nest a Client Component inside a Server Component:

// Server Component
import LikeButton from "./LikeButton";

export default function Post({ post }) {
  return (
    <div>
      <h1>{post.title}</h1>
      <p>{post.content}</p>
      <LikeButton />
    </div>
  );
}

This way, your static content is lightweight, and dynamic features still work!

🪄 Next.js 13+ App Directory Magic

Next.js 13+ introduces the App Router that uses Server Components by default. You just drop files in /app/ and you're using RSCs! Here’s what you get:

• Built-in layout system
• Suspense for async UI
• Automatic streaming

🧱 Best Practices

• Always start with Server Components. Add Client ones only when needed.
• Keep 'use client' at the top!
• Avoid unnecessary interactivity
• Use Suspense to handle loading states

💡 Final Thoughts

Understanding the boundary between server and client is a superpower. It helps you build faster, smarter, and cleaner React apps.

This guide is just the start. If you liked it, check out my GitHub for more real-world examples:

👉 My GitHub

Now go build something epic with React Server & Client Components! 💪