npm (Node Package Manager) is the world's largest software registry and package manager for JavaScript, primarily used with Node.js. Think of it as a massive library or app store for JavaScript code modules that developers can easily install and use in their projects.

When you install Node.js, npm is automatically included. It allows you to:

• Install packages (libraries, tools, frameworks) from the npm registry with a simple command like npm install package-name.
• Manage dependencies for your project through a file called package.json, which lists all the packages your project needs to run.
• Share your own code with millions of other developers by publishing your packages to the registry.
• Run scripts to automate tasks like testing, building, or starting your application.

The npm registry contains over two million packages of reusable code, from small utility functions to large frameworks like React or Express.js. This ecosystem saves developers immense time, as they don't need to "reinvent the wheel" for common features.

To get started, you only need to install Node.js from its official website. You can then open your terminal and use commands like npm init to create a new project or npm install lodash to add a popular utility library. Understanding npm is essential for any modern JavaScript or Node.js development.