What is idempotency in REST?

Idempotency in REST is a property of HTTP methods where multiple identical requests result in the same server state and have no side effects after the first call.

For example, the PUT method is usually idempotent: if you send multiple update requests with the same data, the resource's state will not change after the first update.

This is important for reliability and repeatability of operations, especially in case of network failures, where the client can repeat the request without risking breaking the application's logic.