What is idempotency?

Idempotence is a property of an operation where performing it multiple times yields the same result as performing it once. In simpler terms, if you execute a command several times in a row, the system's state will not change after the first execution.

For example, the HTTP PUT method is usually idempotent: if you send a request to update a resource with the same data multiple times, the result will be the same — the resource will have that data.

Idempotence is important for the reliability of systems, especially in distributed and network applications, where requests may be repeated due to failures or timeouts.