Understand about how Nodejs work

 * Nodejs use 

+ Single-threaded with Event Loop: when a request is made, it is added to the event loop, which is a queue of pending requests. Node.js then continues executing the remaining code, rather than waiting for the request to be completed. When the request is completed, Node.js retrieves it from the event loop and returns the result to the client.

+ Event-driven, non-blocking I/O: allows it to handle multiple requests and connections concurrently without blocking the execution of other code.