In a use case diagram, the user becomes a(n) _____, describing how they interact with a system.

In a use case diagram, the term "actor" refers to any individual or entity that interacts with the system in question. An actor can be a user, another system, or even a hardware device. The primary role of an actor is to illustrate the different ways in which external agents engage with the system's functionalities, representing their goals or needs in the context of the use cases.

By using the term "actor," the diagram provides clarity about who is utilizing the system and how they accomplish their tasks. This helps in understanding user interactions and requirements, which is vital for effective system design and analysis. Therefore, characterizing the user as an actor emphasizes their involvement and the importance of their needs in the development of the system.