Node Package Manager (npm) is the package manager for JavaScript and the world's largest software registry, enabling developers to discover packages of reusable code.

To install an npm package, you only need to run the command npm install <package-name> within your project directory. We are going to use this a lot in the next two chapters.

Let's look at a simple example. If we wanted to use a package (library) like request in our project, we could run the following command on our Terminal, within our project directory:

npm install request

To use it in our code, we require it, like any other module:

const request = require('request');
request('http://www.example.com', (error, response, body) => 
{
  if (error) console.log('error:', error); // Print the error if one occurred
  else console.log('body:', body); // Print the HTML for the site.
});