What is the purpose of a pool in BPMN? What is its main task?

In BPMN, a pool represents the main organizational unit that indicates a separate participant in the process or an organizational boundary. The main task of a pool is to visually and logically separate one business process or organization from another within the diagram. Inside a pool, message flows and processes can be located, and interaction between pools occurs through messages. Thus, a pool helps structure the process by showing who participates and how interactions occur between different parties.