Have you ever get an idea that makes perfect sense in the head, but when you try to explain it to someone else they’re completely lost?

Maybe your idea is for a new app, and every time you talk about it people don’t really understand how they’d intersect with the app and what it would do… This type of scenario where use case diagram is very helpful.

For a basic overview Use case help us to show a system or application, then it shows the people, Organization, or other system that interact with it, and finally it shows a basic flow of what the system or application does.

To understand use-case, let’s break down the diagram into four different elements:

  1. System
  2. Actors
  3. Use cases
  4. Relationships


A system is whatever you are developing. It could be a website, a software component, a business process, an app, etc.

A system represent with a rectangle with name of the application on the top (refer below image):



An actor is represent by a predefined figure (refer below image)


The actor is going to be someone or something that uses our system to achieve our goal. That could be a person, an organization, another system or an external device.

Actor itself divides into two parts:

a. Primary Actor

b. Secondary Actor

Primary Actor: Initiates the use of the system.

Secondary Actor: The reactionary.

This is all about Actor. Let’s move out with our 3rd element “Use Case”.

Use Case:

It represents an action that accomplishes some sorts of task with the system.

For example: If we are making a use-case of banking app which includes.

  • Login
  • Check Balance
  • Transfer funds
  • Make Payments

Our last element “Relationships”.


A actor by definition, is using our system to achieve a goal. So each actor has to interact with at least one of the Use case within our system.

There are three type of relationships in addition to association.

a. Include


c. Generalization

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Hope the above explanation of Use case is clear. Please feel free to share your feedback.

I am a computer Science engineer and a Project Coordinator. Hire me to manage your project 😉