The Node.js event loop, often overlooked, is a multi-step process occurring every millisecond during application execution. The official Node.js website details this loop, which begins upon script execution (e.g., `node index.js`). For simple scripts (like a single `console.log`), the loop starts and ends quickly. However, in more complex applications with ongoing tasks, the loop continuously cycles. This cycle involves processing timers, pending callbacks, idle, prepare, poll, check, and close phases. Understanding these phases is crucial for efficient Node.js development, as they impact how asynchronous operations are handled and the overall application performance.