What is the idempotency of HTTP methods, and how does it apply to PUT or DELETE?

Short answer: Idempotency means multiple identical requests have the same effect as one. PUT → Updating a resource with the same data multiple times results in no further change. DELETE → Deleting a resource repeatedly still results in it being deleted.

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.