What does a Use Case Diagram display?

A Use Case Diagram is a visual representation that captures the interactions between actors and the system being modeled. In this context, "actors" refer to any entities that interact with the system, including users, external systems, or hardware components. The primary purpose of a Use Case Diagram is to illustrate the functional requirements of a system by depicting the various use cases, or what the system is designed to achieve, from the perspective of its users.

By focusing on the relationships and interactions, the diagram helps stakeholders understand how different actors will use the system's functionalities to achieve their goals. This high-level overview is crucial for requirements gathering and validating system behavior from the user perspective. The emphasis on actors is essential for ensuring that the system meets the needs of its intended users and identifies any gaps in functionality that may need to be addressed during development.

In summary, a Use Case Diagram distinctly highlights the actors that interact with the system, making it a vital tool for capturing user requirements and guiding system design.