Modules and imports

What this means

JavaScript modules let one file export code and another file import it. React apps use modules for components, helpers, hooks, and data.

In beginner terms, this topic answers one practical question: "What should I write, and why does React care about it?" Do not try to memorize the syntax first. First understand the idea, then connect the syntax to that idea.

Why it matters

Modules keep files focused. Instead of putting every component into one file, you can export a component from one file and import it where it is needed.

When you build real React screens, this idea helps you decide where data should live, what the user should see, and what should happen after an interaction. That is why this lesson is part of the main path instead of being an optional detail.

Step by step

1. Notice the UI problem this topic solves. 2. Look at the smallest possible example. 3. Change one value and predict what should appear. 4. Run the example and compare the result with your prediction. 5. Use the practice task before moving on.

Small example

export function Header() {}
import { Header } from "./Header";

Common mistake

Do not confuse default exports and named exports. Import syntax must match the way a file exports something.

Practice task

Create a Header component file in your mind, then write the import line you would use from App.

Remember this

Modules let React apps grow across files.