The helps the project team to identify the main functions or features of the system and the different users or external systems that will interact with the system.

Use case diagram

A use case diagram is one of the dynamic diagrams used in Unified Modelling  Language (UML). It is used to illustrate the set of actions, services, tasks and functions that a system needs to perform and those to be performed on the system.  Use case diagrams help team members of a project to identify the main functions or features of the system as well as users and external systems that will interact with the system.

Use case diagrams have the following features;

(i) System: to depict the application itself. It is represented using a rectangular box.

(ii) Use case: to represent the system's functionalities. It is represented using an oval shape.

(iii) Actors: to represent the users of the system.

(iv) Relationships: to illustrate the relations between the actors and the use case of the system.