Improvement Service website header
Change Management


What is a use case diagram?

A use case diagram can be used to show the top-level view of a business system and are used to show the things that need to be provided at an organisational, business system or IT system level. Use case diagrams are used to depict the functions of a system and the actors involved in using those functions. A function may be defined as a set of actions that the business users want the IT system to support in order to achieve a specific goal.


For example, the use case diagram may provide a depiction of a customer account system with the various functions that the business users want the system to support in order to achieve a specific goal. A function may be described using the verb/noun rule, such as ‘record customer’.


Why use a use case diagram?

Use case diagrams use a specific notation, which ensures that there is no ambiguity in what you’re trying to convey. If you use a text-based description there is potential for somebody reading it to interpret your message differently which could cause problems in the delivery of the chosen solution.


How is a use case diagram created?

Unified Modelling Language (UML) is the notation most commonly used in use case diagrams. Use case diagrams each describe an overarching objective and contain descriptions of the various actions that the system must perform to achieve this objective. They document the interaction between an actor and the system. Placing a boundary around the system with the actors placed outside allows you to clearly demonstrate the system boundary and that the scope that it must work within.


Use cases are usually created at the requirements documentation phase. You should aim to work alongside the relevant actors within the business in order to fully comprehend the relationships between the various people and systems. You can elicit information about the relationships through workshops, where you ask the attendees to discuss their roles and functions within the business system.

Use Case Diagram

Kelly Hunkin

Senior Business Analyst

Tel: 01506 283885


Heather Adams

Business Analyst

Tel: 01506 282879


Paige Barclay

BA Officer

Tel: 01506 203800


Email the Change Management team

Example of a use case diagram

Example of a use case diagram

You might also like...

Things to consider

Further details can be captured in a use case description which is a textual description of the interactions between an actor and a use case.


phone icon
Our address
COSLA logo SOLACE logo

© Improvement Service, 2018. All Rights Reserved