# BPMN events

Events are the circles. The border tells you when it happens (start, intermediate, end) and the icon inside tells you what happened.

Getting these right is most of what separates real BPMN from boxes and arrows.

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## When it matters

* Modelling anything that waits, times out, or reacts to a message.
* Processes that will run in an engine, where event type decides behaviour.

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## The symbols

| **Symbol**         | **Means**                                                     |
| ------------------ | ------------------------------------------------------------- |
| Start event        | Thin circle. Where the process begins.                        |
| Intermediate event | Double circle. Something happens partway through.             |
| End event          | Thick circle. This path of the process finishes.              |
| Message event      | Envelope icon. Something arrives from another participant.    |
| Timer event        | Clock icon. A duration or a date triggers it.                 |
| Error event        | Lightning icon. Something failed, and the process handles it. |
| Boundary event     | Attached to a task's edge. Interrupts or runs alongside it.   |

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## A few things that catch people out

* A boundary event that interrupts is drawn with a solid border; non-interrupting is dashed.
* Timer start events make the process self-starting. That is a real behaviour, not decoration.
* Multiple end events are fine and often clearer than funnelling every path into one.

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## Related

[BPMN tasks and activitiesRounded rectangles: work being done.](https://help.gocapable.com/diagrams/bpmn-tasks-and-activities.html)

[BPMN gatewaysDiamonds: the path splits or joins.](https://help.gocapable.com/diagrams/bpmn-gateways.html)

[BPMN notation referenceBack to the full symbol reference.](https://help.gocapable.com/diagrams/bpmn-notation-reference.html)

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_Sequence flow stays inside the pool._