What are modules in Node.js, and what is the difference between CommonJS and ES Modules?

Modules are reusable units of code that let Node.js applications split functionality into separate files. Node.js supports two module systems: CommonJS, the older require() based system, and ES Modules, the modern JavaScript standard using import and export. The main differences are syntax, loading behavior, and ecosystem compatibility.

What are modules in Node.js?

A module is a self-contained piece of code that exposes selected functionality and hides its internal implementation. Instead of placing an entire application in one large file, developers divide it into smaller files that can be imported and reused.

Node.js treats every file as a module. A module can contain:

A module usually has two responsibilities:

2.…