Software Architect's Handbook

Use case diagrams

Use cases are text that describes a software system's behavior as it responds to requests from system users, known as actors. An actor is the role for someone or something that interacts with the system and can be a person, organization, or an external system.

Just like with classes in a class diagram, generalizations can be done on actors. Actor generalization is a relationship between actors in which one actor (descendant) inherits the role and properties from another actor (ancestor).

For example, if our domain had different types of managers, such as an HR Manager and a Customer Service Manager, they may both inherit from a Manager ancestor actor:

Actor generalization is graphically represented in the same way that ...