What defines a secondary actor in a use case?

A secondary actor in a use case is defined as an external actor that supports the execution of a use case, providing necessary assistance or services that enable the primary actor to achieve their goal. This concept is rooted in the understanding that while primary actors initiate the interaction with the system to achieve a specific objective, secondary actors contribute indirectly, often facilitating or supplying additional resources needed for the completion of that objective.

For instance, in a library management system, a librarian serves as a secondary actor who aids the primary actor (the library member) in borrowing books. The primary actor has specific goals, and the secondary actor's role is to support those goals by offering services or information.

This contextual understanding distinguishes secondary actors from primary users, system administrators, and stakeholders, as those roles are either directly involved with the system or engaged in broader project dynamics, rather than focusing on the specific support function that secondary actors provide in use cases.