Use cases are specific scenarios that illustrate how a product or service can be used to achieve a particular goal. They help stakeholders understand the functionality and benefits of a system by providing concrete examples. For instance, a use case for a mobile banking app might describe how a user can transfer money to a friend quickly and securely. In software development, use cases serve as a guide for developers and designers to create features that meet user needs. They outline the interactions between users and the system, ensuring that all requirements are considered. This approach can improve communication among team members and lead to better end products.