Open, Closed, and Half-Open States: The circuit breaker has three states:?

Short answer: Closed: Requests pass through normally. Open: Requests are blocked, and fallback logic is applied. Half-Open: After a timeout, a few test requests are sent to determine if the service has recovered.

Real-world example (ShopNest)

If Payment is down, the Order service fails fast with a circuit breaker instead of hanging every checkout thread.

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.