A command-line tool for interacting with the registry and allowing the developers to publish or download packages.

Once you have the code downloaded on your machine, NPM will make it very easy to check whether there is an update available and download those changes when they’re made. More than two bits of reusable code is called a package. That’s just a directory with one or more files in it, along with a file called package.json, which contains all the metadata about that package.