nodejs/Threads

Node.js is often described as single-threaded because JavaScript execution normally happens on one main thread. But Node.js itself can use additional threads behind the scenes for certain operations, while the operating system also handles many networking tasks.

This distinction is important because single-threaded does not mean Node.js can only use one thread. Understanding the main JavaScript thread, the underlying thread pool, and Worker Threads helps explain why Node.js handles I/O well but needs special approaches for CPU-heavy work.