In UML, an activity diagram provides a view of the behavior of a system by describing the sequence of actions in a process. Activity diagrams are similar to flowcharts because they show the flow between the actions in an activity; however, activity diagrams can also show parallel or concurrent flows and alternate flows.
In activity diagrams, you use activity nodes and activity edges to model the flow of control and data between the actions.
Activity diagrams are helpful in the following phases of a project:
As the following figure illustrates, an activity diagram belongs to an activity in the model. When you create an activity diagram, the activity that owns the diagram is displayed in the Model Explorer view and an activity frame is displayed in the diagram editor. After you create the activity diagram, you cannot move it in the Model Explorer view.
The following topics describe model elements in activity diagrams: