In the beginning of design process we build user understanding, and use personas to define who our users are. Next step is to answer the question why they use our product. Here is where scenarios appear.
Scenarios are hypothetical stories that work together with personas. They describe the context behind why the particular persona would use our product or come to our website.
Scenarios give insight into the user’s motivations and goals while using a system, and once we know their expectations, it becomes easier to make users satisfied.
How to use scenarios
Use scenarios during design to ensure that all participants understand and agree to the design parameters, and to specify exactly what interactions the system must support. Translate scenarios into tasks for conducting walk-through activities and usability tests.