In activity diagrams, partitions group the activity nodes and edges that have common characteristics. Partitions provide a view of the behaviors in an activity, but do not affect the control flow or object flow.
You can use several partitions to allocate characteristics or resources to the nodes of the activity. For example, partitions are useful in business modeling and can show which organizational units are responsible for various activities in a business process.
Each partition in an activity has a unique name that describes who or what is responsible for the activities in the partition.
As the following figure illustrates, a partition is displayed as a rectangle in the activity. The name of the partition is displayed above the activity header and the nodes and edges are displayed below the header.