Unified Modeling Language (UML) is a standard way to draw software models. Use the UML templates in Visio for sketching out designs, or for documenting existing designs.
To find the right template to start from, go to File > New and, in the search box, type the name of the diagram you want (or type UML to find all the templates).
Visio 2013 and Visio 2016 Professional have templates for UML 2.0 versions of several diagram types:
Use Case diagram
If you are a Visio Pro for Office 365 subscriber, and have the latest version of Visio, the following UML 2.5 templates are available. Go to File > New > Categories > Software and Database and then choose one of the following:
Where is the UML Model Explorer?
If you’ve built UML diagrams in previous versions of Visio, you might remember using the Model Explorer. Diagrams made with the Model Explorer were locked against editing and some formatting. In Visio 2013 and Visio 2016 Professional, there is no Model Explorer. You simply drag the shapes from the stencils provided. The shapes are unlocked and more flexible, so you can change their behavior if needed. Drawings are also more customizable, yet they still meet the UML standard.