A Choreography formalizes the way business participants coordinate their interactions. A Choreography is a type of process, but its purpose and behavior are different from a standard BPMN process.
A standard process defines the flow of activities of a specific partner entity or organization. In contrast, a Choreography formalizes the way business participants coordinate their interactions. The focus is not on the work performed within these participants, but rather on the information (messages) exchanged between them.
A Choreography is a definition of expected behavior, basically a procedural business contract between interacting participants. It shows the messages exchanged and their logical relations. This allows business partners to plan their business processes for inter-operation without introducing conflicts.
BPMN Choreography diagram
A BPMN Choreography diagram is based on the UML Activity diagram and includes restrictions and extensions as defined by BPMN.