Understanding React Server Components in 2025

React Server Components (RSC) have fundamentally changed how we build React applications. Let's explore what they are and how to use them effectively.

What Are Server Components?

Server Components are React components that render exclusively on the server. They never ship JavaScript to the client, resulting in:

• Smaller bundles - No component code sent to the browser
• Direct database access - Query databases without API layers
• Better performance - Less JavaScript to parse and execute

// This component runs only on the server
async function BlogPosts() {
  // Direct database access - no API needed!
  const posts = await db.query('SELECT * FROM posts');
  
  return (
    <ul>
      {posts.map(post => (
        <li key={post.id}>{post.title}</li>
      ))}
    </ul>
  );
}

Server vs Client Components

Understanding when to use each type is crucial:

Use Server Components When:

• Fetching data
• Accessing backend resources directly
• Keeping sensitive information on the server
• Rendering static content

Use Client Components When:

• Adding interactivity (onClick, onChange)
• Using browser APIs
• Managing component state
• Using effects (useEffect)

The "use client" Directive

To create a Client Component, add the "use client" directive at the top:

"use client";
 
import { useState } from "react";
 
export function Counter() {
  const [count, setCount] = useState(0);
  
  return (
    <button onClick={() => setCount(c => c + 1)}>
      Count: {count}
    </button>
  );
}

Composition Patterns

The real power comes from composing Server and Client Components:

// page.tsx (Server Component)
import { Counter } from "./counter"; // Client Component
import { BlogPosts } from "./blog-posts"; // Server Component
 
export default async function Page() {
  return (
    <div>
      {/* Server Component - fetches data */}
      <BlogPosts />
      
      {/* Client Component - handles interaction */}
      <Counter />
    </div>
  );
}

Data Fetching Patterns

Server Components shine when fetching data:

// Parallel data fetching
async function Dashboard() {
  // These run in parallel!
  const [user, posts, analytics] = await Promise.all([
    getUser(),
    getPosts(),
    getAnalytics(),
  ]);
  
  return (
    <div>
      <UserProfile user={user} />
      <PostsList posts={posts} />
      <AnalyticsChart data={analytics} />
    </div>
  );
}

Streaming and Suspense

Combine Server Components with Suspense for progressive rendering:

import { Suspense } from "react";
 
export default function Page() {
  return (
    <div>
      <h1>Dashboard</h1>
      
      <Suspense fallback={<LoadingSpinner />}>
        <SlowDataComponent />
      </Suspense>
    </div>
  );
}

Performance Benefits

Here's a comparison of bundle sizes:

Best Practices

1. Default to Server Components - Start with RSC, add "use client" only when needed
2. Push client boundaries down - Keep interactive parts as small as possible
3. Colocate data fetching - Fetch data where it's used
4. Use streaming - Don't block on slow data
5. Cache appropriately - Use Next.js caching strategies

Conclusion

React Server Components represent a paradigm shift in how we build React applications. By understanding the boundaries between server and client, you can build faster, more efficient applications.

The future of React is on the server, and that's a good thing! 🚀