SIPOC, Swimlane, Flowchart and UML Activity Diagrams

Not every process needs BPMN. Pick the lightest diagram that answers the question you are asked.

Diagram	What it shows	Use when	Limits
SIPOC	Suppliers, Inputs, Process (4-7 high-level steps), Outputs, Customers on one table	Scoping a process at the start of an improvement project ([[six-sigma-and-dmaic	Define phase]]); agreeing boundaries
Flowchart	Steps and decisions in sequence	One actor, a simple procedure, a checklist	No responsibility, no parallel work or messages
Swimlane diagram	A flowchart with lanes per role or department	Showing who does what and where hand-offs happen	Informal; semantics depend on the author
UML activity diagram	Control and object flow, forks and joins, with UML semantics	Software teams modelling system behaviour alongside other UML models	Weaker for business roles and messages than BPMN
BPMN	Full process semantics: events, gateways, pools, messages	Several parties, exceptions, hand-over to developers or an engine	Heavier; needs training

Rule of thumb

Swimlane diagrams are the ancestor of BPMN pools and lanes; a clean swimlane is often 80% of a BPMN descriptive model.

BPM hub, value-chain-and-value-stream-mapping, bpm-modelling-tools, bpm-lifecycle, worked-example-order-to-cash-redesign. For Mermaid diagrams inside Obsidian see mermaid-chart-guide.