Scenarios are descriptions of one or more users interacting with with a system, device, or process to achieve a goal under specified conditions and constraints. They provide information about the context in which a system has to operate, in a user- and task-oriented way.
Scenarios can be presented as rich narratives (e.g.,an hour or a day in the life of a user) or simple statements describing the triggers and situation that prompts a user to interact with a system. Scenarios sometimes include simple lists of the steps in a task. Scenarios are used in design sessions, walkthroughs, and usability tests to ensure that the system design effectively supports users in a wide range of real-life situations.
They are also known as "task scenarios".
Scenarios and use cases
Scenarios are sometimes called "use cases<". However the term "use case" can be confusing, as it is used with a different meaning in software engineering. One way of illustrating the difference is through the classic example of withdrawing money from a bank.
- Use cases will include the functional steps of: requesting the withdrawl, verifying your identity, specifying the amount of the withdrawl, checking available funds, and receiving the requested money.
- Scenarios may include situations like: visiting an ATM when the bank is closed (in the rain), a tall person using an ATM in glaring sun, getting a withdrawl from a bank teller inside a bank, or requesting the withdrawl in the form of a bank draft (a check).
User-centered design usually tries to have a scenario refer to multiple component use cases (depending on functions required to satisfy the goal of the scenario), and also to have a use case refer to multiple scenarios (depending on the likely triggering situations and goals that reflect the overall expectations for the system in user terms).