An activity diagram allows us to visually represent a series of actions in the form of a workflow. It shows a control flow and is similar to a flowchart. Activity diagrams can be used to model things such as a business process, flow within a use case, and procedural logic.
The following diagram shows the workflow for creating a new membership card:
The activities in an activity diagram can either be sequential or concurrent. An activity is shown as a rectangle with rounded corners. The rectangle encloses all of the elements of an activity, such as its actions and control flows.