What is a use case?

When projects involve multiple stakeholders, it's important to communicate information efficiently and effectively. 

Whether it’s describing how a product works or how customers interact with it, clearly representing information can make all the difference.

A use case is one way to share information. They simplify complex ideas and offer a way to share information visually. 

While software development often works with use cases, businesses across industries can benefit from them. Let’s learn more about the topic, including use case examples.

A use case is a methodology to organize system requirements. 

It comprises a set of possible sequences of interactions between systems and users in a defined environment with a particular goal. 

The use case document includes the environment, goal, and other details to provide a clear picture of the system and overall project.

Use cases are invaluable for software developers, helping them identify potential errors in the system and fix them early on. 

They’re also incredibly beneficial for project management, offering context to anyone involved, from stakeholders to customer service representatives.

Use cases vs. user stories

Use cases and user stories can benefit project management and development teams. However, distinct differences exist between the two. 

User stories are short-form descriptions from a customer’s perspective. They are the story's beginning, setting the stage for a specific feature or workflow. 

Use cases offer greater context, including: 

• The goal of the use case

• The series of paths the system could take

• Post-conditions, defining the actions the system takes after the use case 

Use case vs. test case

People commonly interchange use and test cases, but they have distinct objectives. 

A test case is a group of test inputs and anticipated results that lead to the further development of a particular test objective. You can reuse test cases. They keep teams aligned, validate software features, and can lead to improved software quality.

On the other hand, use cases focus on end-user interaction with the system, seeing how well specific users interact with a system rather than testing out software features. They are based on system requirements and support different paths, while test cases support a single outcome.

A use case has multiple purposes. Use cases can establish requirements, outlining how users interact with the system. 

They can also manage scope, reducing dreaded scope creep and providing context for all development team members. 

One of the most obvious benefits of a use case is that it can reveal potential problems early in the process. Establishing use cases in your development project ensures you'll create a product that is better equipped to serve everyone who interacts with it.

Who creates use cases?

While use cases can benefit every member of a product development team, project or product managers are usually the people responsible for outlining the initial use cases. 

Product managers can keep the team aligned as they address and complete objectives, all while keeping the concerns of the system's users in mind.

While managers typically control the document, team members can add context or additional details to the use case. 

Product developers often add technical and design elements to the use case, which gives the development team necessary insights into the design and creation of the product.

There are two primary types of use cases: 

Business use cases

Business use cases are also referred to as "abstract-level use cases." They tend to be high-level, with a more abstract description that refers only to the business process and actors involved. Business use cases define the actions the business must perform to provide observable results.

System use cases

System use cases have more detail than business use cases. They include the specific system processes that must happen to fulfill the project's goal. System use cases are also known as "implementation use cases."

Companies can use both cases. Many project managers start with business use cases to provide high-level overviews before moving on to system use cases for a more granular level of detail.

A typical use case contains the following six elements, whether high-level or micro-detailed:

1. Actors

In the context of a use case, an actor is anyone who performs a behavior or interacts with your system. An actor doesn't have to be an individual. It can also be a company or a team.

2. Systems

The system is the product that provides the backdrop for your actors’ interactions. It is also called the scene or the subject.

3. Goals

Goals are the results of the participating actor's interactions with the system. You can discuss these goals at the project’s outset with all stakeholders and members of the development team.

4. Preconditions

In any use case, it’s crucial to meet certain conditions before and after the use case. These are called preconditions. They’re invaluable for software developers, allowing them to visualize the steps users experience as they interact with the system.

5. Basic flow

The basic flow is when a use case operates as outlined and intended, with no deviations or errors. Deviations are normal, so a basic flow is often the starting point for development.

6. Alternative flows

Alternative flows are when any deviations occur from the basic flow. This can manifest when a system-level error occurs or when users interact with the system in unexpected ways.

A use case diagram visually represents your system's actors and their interactions with the system. Use case diagrams can be particularly helpful for product developers and designers, clearly depicting actors, scenarios, and goals.

To write a use case, clearly define the target audience you want to focus on. From your target audience, isolate a single user. They can serve as the actor for your use case. 

Work with your development team to create an outline that includes the typical flow of events when the actor uses the product or service. This is the basic flow you and your team operate from.

Include alternative flows in the use case. Provide examples of how to proceed in the event of all flows so your development team has more to work with. 

Once the use case is complete, share it with those involved in the project. Consider the feedback you receive and incorporate it into the use case as necessary.

There's no single format for use cases. Depending on the nature of your project and your company's needs, you could include or eliminate various sections. 

You can use this basic section outline as a starting point for your use case:

• Use case name

• Summary

• System details

• Actors/primary actor

• Preconditions

• Basic flow

• Alternative flows

• Goal

• Stakeholders

You might also include a priority in your use case to define the project's urgency. 

Including a use case diagram with your outline can also be helpful to provide visual cues to any non-technical people reviewing the use case.

An actor in a use case is someone who interacts with the system. To identify an actor for your use case, consider what the system handles and what is handled outside the system. 

Additionally, consider what the actor needs from the system and the expected outcome.

A secondary actor in a use case provides a service to the system you’re refining. Secondary actors do not trigger interactions with the use case and are often termed "supporting actors" by those involved in the project.