What are idempotent operations, and why are they important in RESTful design?

Short answer: Idempotent = multiple identical requests have the same effect as one request. Important for reliability and safe retries. HTTP Methods: GET, PUT, DELETE → Idempotent. POST → Not idempotent (creates new resource each time).

Real-world example (ShopNest)

Creating an order is POST /api/orders → 201 with Location header. Fetching is GET /api/orders/{id} → 200 or 404.

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.