Subprocesses have two major use cases:

• Sequence flows can not cross subprocess boundaries.
  A subprocess is visualized as a typical activity, i.e., a rounded rectangle. In case the subprocess is collapsed, only the name and a plus-sign are displayed, giving a high-level overview of the process:

One of the main reasons to use a subprocess is to define a scope for a certain event. The following process model shows this: both the investigate software and investigate hardware tasks need to be done in parallel, but both tasks need to be done within a certain time, before Level 2 support is consulted. Here, the scope of the timer (i.e., which activities must be done in time) is constrained by the subprocess.

Camunda Extensions

Additional Resources