npm means Node Package Manager. NPM is an online repository for the publishing of open-source Node.js projects. Other things, it is a command-line utility for interacting with given repository and aids in package installation, version management, and dependency management. The use of npm in node.js is dependency management. When you have a node project with a package.json file, you can run "npm install" command from the project root and npm will install all the dependencies listed in the package.json.
There are following main features of Node Package Manager (NPM):-
1. Online repositories management for node.js packages/modules it searches on search.nodejs.org.
2. Command line utility to install Node.js packages, do version management and dependency management of Node.js packages.
To check Node Package Manager (NPM) version in you pc then you type the following command:-
$ npm --version
To installed packages/dependencies Globally in system then execute the following command:-
$ npm install express -g