A Use Case diagram captures Use Cases and relationships among Actors and the subject (system). It describes the functional requirements of the system, the manner in which outside things (Actors) interact at the system boundary, and the response of the system.
The diagram below illustrates some features of Use Case diagrams:
Toolbox Elements and Connectors
Select Use Case diagram elements and connectors from the Use Case pages of the Enterprise Architect UML Toolbox.
Tip: Click on the elements and connectors below for more information.