Can you explain how the event processing loop works in asynchronous systems?

Event loop in asynchronous systems like Node.js is responsible for managing the execution of asynchronous operations without blocking the main thread.

Working principle:

1. All time-consuming operations (e.g., file reading, network requests) are sent to the event queue.
2. The event loop constantly checks this queue and, when an operation completes, it calls the corresponding callback or handler.
3. The main thread is not blocked; it continues executing the next code until completed events appear.

This allows efficient resource utilization and the handling of many operations in parallel, despite Node.js's single-threaded nature.

Example:

console.log('Start');
setTimeout(() => {
  console.log('Asynchronous event');
}, 1000);
console.log('End');

The output will be:

Start
End
Asynchronous event

Because setTimeout places the function in the event queue, and the event loop calls it later.