The event loop in Node.js is a single-threaded loop which is responsible for processing events from the event queue, handling I/O operations, and executing asynchronous callbacks. It is a continuous process that runs until the program exits. The event loop allows Node.js to perform non-blocking I/O operations, making it efficient and fast. The event loop works by taking the events from its event queue, executing each one in order, and then repeating the process. Through this loop, Node.js can handle multiple requests simultaneously without blocking, or waiting for a response before processing another request.