Use Case Diagram Templates of Common ScenariosĪ UML (Unified Modeling Language) use case diagram is a visual representation of the interactions between actors (users or external systems) and a system under consideration.Use case diagram is a behavioral UML diagram type and frequently used to analyze various systems. They enable you to visualize the different types of roles in a system and how those roles interact with the system. This use case diagram tutorial will cover the following topics and help you create use cases better.