![Use case diagrams are UML diagrams describing units of useful functionality (use cases) performed by a system in collaboration with external users (actors). Use case diagrams are UML diagrams describing units of useful functionality (use cases) performed by a system in collaboration with external users (actors).](https://www.uml-diagrams.org/use-case-diagrams/business-use-case-diagram-elements.png)
Use case diagrams are UML diagrams describing units of useful functionality (use cases) performed by a system in collaboration with external users (actors).
![Relationships in Use Case diagram | example on use case diagram| Generalization| Extends | Includes - YouTube Relationships in Use Case diagram | example on use case diagram| Generalization| Extends | Includes - YouTube](https://i.ytimg.com/vi/KZM-_ysiAMg/maxresdefault.jpg)
Relationships in Use Case diagram | example on use case diagram| Generalization| Extends | Includes - YouTube
![Use case diagrams are UML diagrams describing units of useful functionality (use cases) performed by a system in collaboration with external users (actors). Use case diagrams are UML diagrams describing units of useful functionality (use cases) performed by a system in collaboration with external users (actors).](https://www.uml-diagrams.org/use-case-diagrams/use-case-diagram-elements.png)