What is the cluster module?

Short answer: The cluster module lets you fork your Node.js process to create worker processes that share the same server port, improving CPU utilization. Testing Node.js Applications

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.