npm is a node package manager used to install, uninstall packages on Nodejs and Javascript.

npm comes with installation of Nodejs. Nodejs is a javascript runtime to run javascript code on server side.

NPM is a package manager for javascript applications, create a reusable, publish and share the code by different users.

npm package manager

with npm package manager, you can do following code

Create a Reusable packages, publish to repositories, and share the with other applications
Install/ Uninstall packages
Update/downgrade packages

npm tutorial