Scenario testing evaluates a design concept by walking users or stakeholders through a realistic narrative description of how the product or service would be used in a specific context, without showing a prototype. The scenario is read aloud or presented as a written vignette, and participants respond to the described experience as if they were living it. Scenario testing is particularly useful at early stages of development when a prototype does not yet exist, or when the design challenge is too complex to prototype fully within the available time.