A
concrete use case is initiated by an actor and performs the entire behavior desired by the actor [RUP]. These are the elementary business process use cases. For example,
Process Sale is a concrete use case. By contrast, an
abstract use case is never instantiated by itself; it is a subfunction use case that is part of another use case.
Handle Credit Payment is abstract; it doesn't stand on its own, but is always part of another story, such as
Process Sale .