This chapter introduces the core concepts of process modeling with BPMN. We will not explain every single symbol you
can find in the diagrams, but show how process modeling in BPMN is basically done, how we can use pools and message
flows for explicitly modeling collaborations between participants, and how we can (de-)compose process models with
sub-processes and call activities. Those examples do not contain executable process models, but represent process models
focusing on organizational aspects of business processes.