Before going further to install NodeJS first we need to understand what is node JS and what is npm.
What is NodeJS?
What is NPM?
Follow the following steps to install nodeJS and npm in Windows:
Download Node.js Installer https://nodejs.org/en/download/
Simple Wizard to install node.js simply next next and next ask you a some questions and then finish it
Verify Installation | Open Command Prompt and execute following command
It will return which version of node.js you had installed
Check the version of node package manager npm