Failure

A Failure is an event where a system or component ceases to perform its intended function within a specified timeframe or acceptable limits. A failure is often the direct result of an underlying defect becoming active under certain conditions.

Example: A Failure occurs when a user tries to access a payment processing page, and the page returns a 404 Not Found error instead of loading the payment form. The underlying cause might be a defect in the code that incorrectly routes the request, but the visible Failure is the system's inability to perform its required function.