NodeJS is capable of handling multiple requests happening at the same time from a single thread in an event loop. This event loop takes in any events and returns multiple event handlers one at a time. Since the event handlers are small, it can process requests as quickly as possible. With one thread handling multiple requests compared to multiple threads, the app acts much quicker from the back-end, and processes requests from the user as soon as possible.
We use NodeJS for mobile application development to create real time functions, making it the AJAX equivalent for mobile apps. NodeJS helps to handle the app's client requests to the server to perform back-end functions and send back the results to display it on the app. With the possibility that multiple clients can send requests to the server, we use NodeJS because it handles multiple requests to the server without slowing down the app and causing other problems.