A use case in design or software development is a way of identifying specific needs that a person might have in engaging with a product or service to accomplish something.
Use cases go beyond the person’s needs, objectives, and outcomes to include describing how the people and systems involved interact with each other through the flows and engagements that are necessary to achieve the goal.
Use cases are a way of determining what the design requirements should be when delivering a product or service, including mapping these requirements back to user goals and actions, interface behaviours, and organizational needs and objectives.