What is an event loop in Node.js and how does it work?

In Node.js, the event loop is a mechanism that allows asynchronous operations to be handled efficiently without blocking the main thread. It is responsible for managing all asynchronous operations and callbacks in a non-blocking way.

Here's how the event loop works in Node.js:

1. When a Node.js application starts, it initializes the event loop.
2. Any asynchronous operation in Node.js is executed outside the main program flow and is added to the event queue.
3. The event loop continuously checks the event queue for any completed asynchronous operations.
4. When an asynchronous operation is completed, its callback function is added to the callback queue.
5. The event loop then processes the callback queue and executes the callback functions one by one.
6. This cycle continues indefinitely, allowing Node.js to handle multiple asynchronous operations efficiently.

By using the event loop, Node.js can handle a large number of concurrent connections and perform I/O operations without blocking the main thread, making it a powerful platform for building scalable and high-performance applications.