Providing appropriate, and immediate, feedback within a system is the most basic guideline of user interface design.

Feedback helps the user interact more efficiently with the system by letting them know when an interaction was successful or unsuccessful. The sooner the user knows an error was made, as well as how and why it was made, the sooner they can fix it.

Feedback can be as small and simple as a color change, but it aims to reduce uncertainty and confirm to the user that the system is working properly and responding to their input.