Repeated requests and idempotency
An idempotent operation does not further change the intended server state when repeated. Responses need not be identical. POST is not automatically idempotent.
A concrete example
If a payment response is lost, retrying should not create a second payment. An application can atomically store an operation key, payload and result, rejecting different payloads for the same key.
Idempotency-Key: order-42-attempt-1Explain it yourself
Why is disabling a button insufficient protection against repeated requests?
How to study this
Write your reasoning first. Check the original documentation, identify an assumption, then try a different example. Reading this page does not count as verified skill evidence.
Source and review
Original RealDeveloper explanation; last source check: .