A deviation from the specified or expected behavior that is visible to end-users is called?

A failure refers to the situation where a system or component does not perform its intended function, leading to a deviation from the specified or expected behavior as perceived by the end-users. This could manifest in various ways, such as incorrect outputs, system crashes, or unresponsive features. Failures are directly observable by users and indicate that something within the system did not work as promised or designed.

Understanding the distinction between different terms is essential. An error generally refers to a mistake made by a human during the development or testing processes, while a fault is a bug or flaw in the software code that can potentially lead to a failure. A defect is a broader term often synonymous with fault and indicates any deviation from requirements. However, only when the fault is executed in a live environment can it be directly perceived as a failure by users.