idempotency concept
An operation is idempotent if applying it more than once has the same effect as applying it once: f(f(x)) = f(x).
An operation is idempotent if applying it more than once has the same effect as applying it once: f(f(x)) = f(x). Critical in distributed systems because retries are unavoidable — networks fail mid-request and clients can't tell whether the server processed it. PUT and DELETE are conventionally idempotent in HTTP; POST is not. Note: idempotency is specifically about repeated application of the same operation, distinct from commutativity (order doesn't matter) or associativity.