What is Node.JS?
As we all know that JavaScript runs only on the client-side (browser).
But, what if you want to run JavaScript on the server-side to build a dynamic website based on a database, or you want to do file handling using the JS, then Node.js will help you to do this sort of thing.
So Node.js is not a programming or scripting language, it provides a runtime environment to your system that helps JavaScript to run as a server-side language.
It is Free and supports cross-platform, which means you can run it on various platforms such as Windows, Linux, Unix, Mac OS X, etc.