Well, per others' responses the "no side effects" part is not quite accurate. The definition in plain English is actually pretty simple: idempotency = "has the

Well, per others' responses the "no side effects" part is not quite accurate. The definition in plain English is actually pretty simple: idempotency = "has the same effect, no matter how many times it's run". Like a dedicated "Power On" button (vs a "power toggle" button).