NodeJS is JavaScript that runs on the server. A server is a special computer on the Internet that will host your website. The computer on which the site is being developed can also be made as server.
NodeJS allows the server to generate HTML code, which will then be sent to the browser (to client). In addition, NodeJS allows you to work with the database and server file system.
In addition, NodeJS is an environment in which handy JavaScript tools will run on your computer. It is exactly the feature that we still need. And a special tutorial is devoted to using NodeJS as a server.
Install NodeJS following the instructions at the following link.