Modern software applications often depend on multiple services, APIs, and external systems, where network failures and automatic retries are common. A major challenge is ensuring that repeated requests do not accidentally create duplicate records or trigger the same operation multiple times.

For example, if a user submits an order and the network times out, the client may retry the request. Without proper handling, the backend could create the same order twice. The problem is designing APIs that can safely handle such duplicate requests while maintaining data consistency and reliability.