A confirmation message is displayed to a customer after the purchase of product is completed on an ecommerce site. This is an example of which user interface design principle?

• A. Feedback
• B. Tolerance
• C. Structure
• D. Visibility

Answer: (A)

Providing feedback after a user action is what this example shows. When the purchase is completed, the confirmation message communicates the outcome, letting the customer know that the transaction went through and often providing key details like an order number and next steps. This immediate response helps the user understand what happened, reassures them, and closes the interaction loop so there’s no ambiguity about success. While visibility can play a role in making the message easy to notice, the essential idea highlighted here is feedback—the system communicating the result of the user's action. The other principles aren’t demonstrated as directly: structure is about organizing content, and tolerance is about forgiving mistakes or allowing mistakes to be recovered from, not about signaling action results.