An event is something that happens during the execution of a process and has an impact on the flow. An event alters the sequence or timing of activities in a process. Some events have a trigger, such as a timer, message, signal, error, manual trigger or API call.
There are three types of event: start, end, and intermediate. A start event is at the start of a process flow, and an end event is at the end of a flow. An intermediate event is an element in a flow of the diagram or is attached to the boundary of a task or call activity.
The following table shows the events that you can use in a process diagram. Events that can be set as boundary events are marked (B). A non-interrupting time can only be set as a boundary event (B only):