Articulating how a customer will interact with a product or system is essential for requirements gathering and high-level stakeholder communication. A use case model diagram is a visual representation of a product’s users, how they will interact with the product, and what the product does. But what is a use case, exactly, and why is it an important tool for project managers? 

Though commonly used to break down complex ideas in a software development environment, use cases in project management can be just as vital for gathering requirements and establishing a project’s scope. 

Learn more about how to write a use case and how a use case model tool can be used when establishing essential project requirements. 

A use case is a description of the ways in which a user interacts with a system or product. A use case may establish the success scenarios, the failure scenarios, and any critical variations or exceptions. A use case can be written or made visual with the help of a use case model tool. 

Swedish computer scientist Ivar Jacobson presented the first article on use cases in 1987, describing how the technique was used at telecommunications company Ericsson to capture system requirements. In 1992, Jacobson co-authored the book "Object-Oriented Software Engineering — A Use Case Driven Approach," which helped popularize use cases for specifying functional requirements in software development.

Jacobson later joined American software engineers Grady Booch and James Rumbaugh to create the Unified Modeling Language (UML), which introduced a standard way to visualize the design of a system. Since then, the technique has been adapted into use case writing "templates" to streamline the capture of high-level requirements.

The purpose of a use case is to:

Project managers need to know about use cases because they help communicate strategy to stakeholders and bridge the gap between business justification and technical requirements.

PMI also notes that “use cases provide a structure for gathering customer requirements and setting the project scope.” But what does that mean in practical terms? 

Let’s say that you are a project manager for an education tech firm. Your company’s latest product idea is an app for students where they can receive live tuition for a monthly subscription fee. Creating a use case for this application can tell stakeholders and the project team who the customer is, how the customer will interact with the product, and what the scope gap meaning and requirements of the project will be. 

When presented in written form, a use case can be a helpful piece of project documentation. Use cases are a common requirements artifact, and they can smoothen communication across technical and business stakeholders. 

Depending on the intended audience and system under discussion, the use case can be as detailed or basic as needed. A use case document should establish and identify a few key components — these are: 

This use case illustrates how both the customer and restaurant employee (the actors) interact with the food delivery application (the system) and the expected outcome of each interaction.

This helps sketch a framework for what is expected in the development stage. The app must be able to process payments, for example.

A use case model is a visual representation of the interactions between an actor and a system. As PMI also notes, use case models depict processes, which helps to further express preconditions and triggers.

A use case model is commonly expressed using UML (Universal Modeling Language). In these visualizations, there are three main components: the system, the actors, and the use case.

The system is represented by a rectangle or “boundary box." Actors are shown as stick people outside of the boundary box, while the use cases are presented as text in ovals within the box. Solid and dashed lines represent the association between the actors and the system’s use cases. 

A use case diagram is simply a type of use case model. A use case model diagram uses text and shapes to represent the relationship between a user and a system. 

Primarily, use case model diagrams are used to: 

Depending on the system, a use case model diagram can vary in complexity, showing basic associations or expanding to show multiple exceptions. 

With Wrike, you can store and share use cases and other documentation in a single, centralized digital repository. Create use cases using a modeling tool or product management use case template, upload them to Wrike, and communicate with multiple stakeholders at once using @mentions and task assignees. 

Document project scope and requirements with your use cases and make them available to everyone who needs to see and reference them. No more endless email chains and lost DMs. With Wrike, project planning and documentation are made easy.

Want to learn more about sharing your use cases in Wrike? Sign up for a free two-week trial and discover why 2,000,000+ users choose Wrike for better project management.