Actor (UML)
![UML use case diagram with two actors and several use cases.](/Images/godic/202502/19/Use_Case_diagram_V15944.JPG")
![](/Images/godic/202502/19/Use_case_restaurant_model.svg5944.png")
An actor in the Unified Modeling Language (UML) "specifies a role played by a user or any other system that interacts with the subject."
"An Actor models a type of role played by an entity that interacts with the subject (e.g., by exchanging signals and data), but which is external to the subject."