UML (Unified Modeling Language) use case diagrams show the functional requirements of a system from the end user's perspective. These diagrams focus on how the system should ideally function and help clarify requirements, detect problems early on, and simplify a system’s design. 

This article’s content is a preview of the “UML use case diagrams in Lucidchart” Training Labs course. Register to access all the content for free.

Add UML shapes

You’ll be using the same shapes over and over again, so a pre-created shape library cuts down on time by allowing you to simply drag and drop shapes and ensure they’re always consistent and within reach.

To add a shape library to the shapes panel:

1. Select the “More shapes” button on the left.

2. Type “UML.”

3. Select “UML use case.” 

4. Select “Use selected shapes.”

The library will be added in the left-hand panel under “UML use case.” Now, you can drag and drop shapes from the UML use case shape library onto your board as many times as you’d like, and they’ll remain consistent each time and for every collaborator.

Show association relationships

Shapes on your board are related to each other somehow, and the easiest way to show those relationships is with connecting lines. 

To draw lines between shapes:

1. Hover over a shape so that the purple nodes appear.

2. Click a node to start a line, then drag that line from the starting shape to the ending shape.

To find and apply line options:

1. Select the line and then find “Line options” in the contextual toolbar.

2. Select whichever type of line or thickness you’d like.

Show use cases

Now it’s time to make your use cases more descriptive by defining relationships between shapes. 

 For “include” and “extend” use cases:

1. Click on a shape’s purple node and drag it to the ending shape.

2. Select the endpoint of a line and choose the arrow that indicates the correct direction of the relationship.

3. Add text by double-clicking on a line and typing “include” and “extend” or any other descriptive text.

4. Move the text by clicking on the text box and dragging it wherever you’d like.

Register for the course to learn how to add collaborators to a board and access other great content, such as guides and video tutorials. Soon, you’ll be able to quickly and easily create UML use case diagrams that can be shared with your entire team in just a click.