The following table describes the types of control nodes that you can use in activity diagrams.
| Control node type | Description | Icon |
|---|---|---|
| Activity final | This node represents a point where all flows in an activity stop. An activity can have several activity final nodes. When the first activity final node is encountered, all flows stop and the activity terminates. |  |
| Decision | This node represents a point in an activity where a single incoming edge divides into several outgoing edges. You typically use constraints, also called guard conditions, on the outgoing edges to determine which edge should be followed. |  |
| Flow final | This node represents a point where one flow in an activity terminates, but does not affect the other flows in the activity. |  |
| Fork | This node represents a point in an activity where a single incoming flow divides into several outgoing flows. |  |
| Initial | This node marks the point at which flow begins when the activity or structured activity node is invoked. An activity can have several initial nodes, which means that several flows with start when the activity is invoked - one for each initial node. |  |
| Join | This node represents a point in an activity where several incoming flows are synchronized into a single outgoing flow. |  |
| Merge | This node represents a point in an activity where several incoming edges come together into a single outgoing edge. |  |