I explained that Node.js uses a single-threaded event loop along with non-blocking I/O. When an asynchronous operation like a database call or API request is made, Node.js offloads it to the system or worker pool and continues executing other code. Once the operation completes, its callback or promise is placed in the event queue and processed by the event loop. This approach allows Node.js to handle a large number of concurrent requests efficiently without blocking the main thread.