What does it mean for a system or operation to be idempotent?

Idempotence is a property of an operation or system where multiple executions of the same operation with the same input data do not change the result after the first application.

For example, if you have an HTTP PUT request to update a resource, calling it repeatedly with the same data will not further change the state of the resource.

This is important for ensuring the reliability and predictability of systems, especially in distributed and networked applications.