What are idempotent operations in the context of requests and how do they differ from non-idempotent ones?

Idempotent operations are operations that can be performed multiple times in succession without changing the result after the first application. In the context of HTTP requests, idempotency means that a repeated request with the same parameters will not further alter the server's state.

For example, requests like GET, PUT, DELETE are considered idempotent:

• GET — simply retrieves data without changing it.
• PUT — updates a resource, and repeating the update with the same data will not change the result.
• DELETE — deletes a resource, and deleting the same resource again will not change the state (the resource is already deleted).

Non-idempotent operations, such as POST, can create new resources or change the server's state with each call, so a repeated request may lead to different results or side effects.

Idempotency is important for the reliability of systems, especially when repeated requests are made due to network failures or timeouts, to avoid unwanted changes or duplicate actions.