What is node.js ??

Answer 1

A backend framework for js allowing you to store files, make servers etc... (what web js cant do)

Answer 2

It is a framework to work in the Backend with JS.

https://www.w3schools.com/nodejs/nodejs_intro.asp

Answer 3

Node.js is an open source server framework
Node.js is free
Node.js runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.)
Node.js uses JavaScript on the server
for more:
https://www.w3schools.com/nodejs/nodejs_intro.asp

Why Node.js?

Node.js uses asynchronous programming!

A common task for a web server can be to open a file on the server and return the content to the client.

Here is how PHP or ASP handles a file request:

Sends the task to the computer's file system.
Waits while the file system opens and reads the file.
Returns the content to the client.
Ready to handle the next request.

Here is how Node.js handles a file request:

Sends the task to the computer's file system.
Ready to handle the next request.
When the file system has opened and read the file, the server returns the content to the client.

Node.js eliminates the waiting, and simply continues with the next request.

Node.js runs single-threaded, non-blocking, asynchronously programming, which is very memory efficient.
What Can Node.js Do?

Node.js can generate dynamic page content
Node.js can create, open, read, write, delete, and close files on the server
Node.js can collect form data
Node.js can add, delete, modify data in your database

What is a Node.js File?

Node.js files contain tasks that will be executed on certain events
A typical event is someone trying to access a port on the server
Node.js files must be initiated on the server before having any effect
Node.js files have extension ".js"

Answer 4

It's a server side JS interpreter that allows you to create powerful web applications easily using a familiar language.