✅ Difference Between React and ReactDOM

When starting with React, one of the most common questions is:
“What’s the difference between React and ReactDOM?”

They’re closely related, often used together, but they play very different roles in the React ecosystem. Understanding this separation is key to building clean, scalable React applications.

🔹 What Is React?

React is the core library used to build UI components and manage application logic.

It provides:

JSX support
State management (useState)
Side effects (useEffect)
Component composition
Lifecycle behavior (via hooks or class methods)

👉 Important: React does not render anything to the browser by itself. It only describes what the UI should look like.

Example: Creating a Component with React

import React, { useState } from "react";

function Counter() {
  const [count, setCount] = useState(0);

  return (
    <div>
      <h2>Count: {count}</h2>
      <button onClick={() => setCount(count + 1)}>
        Increase
      </button>
    </div>
  );
}

export default Counter;

Here, React:

Defines the Counter component
Manages state
Describes the UI

But at this point, nothing appears on the screen yet.

🔹 What Is ReactDOM?

ReactDOM is the renderer that takes React elements and mounts them into the real browser DOM.

It acts as the bridge between:

React’s virtual UI descriptions
The actual HTML DOM

Without ReactDOM, React components would remain pure JavaScript objects.

Example: Rendering with ReactDOM (React 18+)

import React from "react";
import ReactDOM from "react-dom/client";
import Counter from "./Counter";

const root = ReactDOM.createRoot(
  document.getElementById("root")
);

root.render(<Counter />);

Here, ReactDOM:

Finds the real DOM node (#root)
Converts React elements into actual DOM updates
Keeps the UI in sync with state changes

📚 React vs ReactDOM — Quick Comparison

Aspect	React (Core Library)	ReactDOM (Renderer)
Primary role	Build components & manage logic	Render components into the browser
Handles	JSX, hooks, state, effects	DOM mounting & updates
Runs in	Any JS environment	Browser DOM
Without it	UI logic only (not visible)	No UI rendered in browser

🧠 Mental Model (Easy to Remember)

React → What should the UI look like?
ReactDOM → Put that UI into the browser.

Or:

React is the architect.
ReactDOM is the builder.

✅ Best Practices

Keep component logic inside React components.
Use ReactDOM only at the entry point (index.js / main.jsx).
Prefer ReactDOM.createRoot() for modern apps (React 18+).
Write reusable components—React handles behavior, ReactDOM handles rendering.

🧾 Final Thoughts

React and ReactDOM are designed with a clear separation of concerns:

React defines what your UI is and how it behaves.
ReactDOM decides where and how that UI appears in the browser.

Once you understand this split, many React concepts—like Virtual DOM, reconciliation, and multiple renderers (React Native, React DOM, React Server)—start to make much more sense.

Difference Between React and ReactDOM with Examples