As applications grow, writing all code in a single file becomes hard to manage.

Modules allow you to split code into multiple files and reuse it where needed.

You can export values from one file:

// math.js
export const add = (a, b) => a + b;

And import them in another file:

// app.js
import { add } from "./math.js";

console.log(add(2, 3));

This keeps code organized and makes it easier to maintain.

Modules are widely used in backend development to separate logic, utilities, and features into different files.