What is node.js? Why should we use it?

The question of what is node.js is very confusing for some people. Some consider it a programming language and for some, it is a kind of software that can be installed on the computer. In this article, we are going to discuss some of the important questions related to node.js.
First of all, we will start with a simple and straightforward answer to the question and later will discuss the other related topics that will help us understand the topic more accurately.
What is node.js?
If we start with the official definition of Node.js on the official website, then Node.js® is an open-source, cross-platform JavaScript runtime environment.
But this definition leads us to more questions. What is open-source? What is cross-platform? and most importantly, What is Runtime environment?
What is a runtime environment ?
What is the use of node.js?
Why Node.js?
There are many other programming languages that can be used as a backend language of the server. The most famous are PHP, Python, Ruby, etc.
Conclusion
So in conclusion we can say that node.js is not a programming language. It is a runtime environment that helps us to run javascript outside of the browser.