Node.js in itself is a wrapper around V8, the JavaScript engine of Google Chrome. It is used to execute JavaScript on the server for example to implement REST APIs. I would consider Node.js if you implement actual webbased software because you could take advantage of a shared codebase. If you want to display content on the internet there are more comfortable alternatives you could use.
What you are probably looking for is Node-Webkit. It is a toolkit to basically pack a stand alone application with a browser and node.js to create a desktop application.
I personally would recommend to use QT or GTK or some Windows framework if you want to learn how to program a desktop application. No need to deal with the performance problems of web technology and then ship a whole browser with your app if you have to learn something new anyway. In my opinion you should use Node-Webkit only if you know why you use it or if you do not know how to use anything else.
I programmed some Desktop Apps with Java and C#. And during some hackathons i used python+flask+nginx to implement a Web-Applications with a RestAPI on the backend.
I was just curious for which type of application i can use node.js (since i didn't use javascript on the backend at all). Usually i used PHP, C# or Pyhton for the backend..
Is MS Windows 10 using node.js for their applications (since its possible to develop Node.js apps in Visual Studio Code)?
I do not think, that node.js is involved in the JavaScript apps for Windows. In your place I would test node.js the next time you do something like you did with Flask. If you now C#, I would not recommend to waste time to implement a node-based Windows GUI app.
I think you can develop Windows 10 apps using JavaScript, but as far as I know Node.js isn't involved. I think Microsoft promotes Node.js more so that people use their Azure platform to host Node.js applications.
You can use Node in place of PHP or Python to implement a REST API backend. You can also use it to run scripts the same way you would use Python to do that.
Windows doesn't use node, they have their own JS runtime and a GUI framework that you can script with JS.
What you are probably looking for is Node-Webkit. It is a toolkit to basically pack a stand alone application with a browser and node.js to create a desktop application.
I personally would recommend to use QT or GTK or some Windows framework if you want to learn how to program a desktop application. No need to deal with the performance problems of web technology and then ship a whole browser with your app if you have to learn something new anyway. In my opinion you should use Node-Webkit only if you know why you use it or if you do not know how to use anything else.