Since activity diagrams shows the actual flow events (unlike use case diagrams), you need to know where to start and where to stop. Luckily there are three very simple nodes you can use to indicate this flow. They are:
This node indicates the beginning of your activity diagram. There can only be one of these on a diagram.
This node indicates the end of your activity. There can be more than one.
This node indicates the end of a particular flow (if it has split up, which I’ll discuss later). This node does not, however, indicate the end of the activity as a whole!