Node.js, a popular choice for backend development, is fundamentally single-threaded but employs a sophisticated event loop and worker pool to manage asynchronous I/O operations efficiently. While the main thread handles JavaScript operations and incoming requests, Node.js can utilize auxiliary threads, known as worker threads, to perform tasks concurrently without blocking the main event loop. The introduction of the worker_threads module allows developers to create multi-threaded applications by spawning threads that can execute independently. This module supports two main approaches: executing tasks with individual worker threads or using a worker pool to manage and reuse threads for multiple tasks, enhancing performance and scalability. Despite the challenges of synchronizing multithreaded processes, Node.js's ability to perform non-blocking I/O operations and its support for worker threads make it a powerful tool for building high-performance applications, even in compute-intensive fields like AI and big data.