We know that a Node.js application is run in a single-threaded fashion. But, it can handle multiple asynchronous operations in the background and exhibits features as if it is a multi-threaded application. At the base level, Node.js is built on C++ which actually allows the existence of multiple threads. While that's not the actual basis, Node.js utilizes the libuv library that allows it to interact with the operating system and utilize available resources efficiently. The library enables asynchronous I/O operations such as file reading, database querying, data transferring over the network, and so on, then it will trigger the registered callback for each completed I/O operation to run. Node.js manage all the callbacks in a mechanism called " event loop ". An event loop is a loop of sequential processes which are grouped into several phases. It handles callbacks of asynchronous I/O operations and asynchronous calls initiated by objects or functions in the main appl...