After a user acts, the interface should make the resulting state understandable. Feedback is the perceptible response that connects an action to what the system did.

A pressed control can change appearance immediately, a save operation can report success or failure, and a long operation can show that work is still progressing.

Feedback should distinguish states that require different user decisions. “Something happened” is weaker than showing whether a request is pending, completed, partially completed or failed.

For longer operations, progress indicators should reflect what is actually known. A determinate indicator is useful when remaining work can be estimated; otherwise an indeterminate indicator can at least show that the system has not silently stopped.

Feedback must also avoid claiming success before an operation is durably complete. Optimistic interfaces can respond quickly, but they need a recovery path if the underlying operation later fails.

Visible status closes the interaction loop: act, observe the result, then decide what to do next.