An event is something that happens during the execution of a process. They can catch or throw processes. For example, a process could be modeled to start when a certain condition is met or when a timer notifies that a certain time period has elapsed. An event is represented by a circle and the border style shows the type of event.
There are three types of events:
Below you can see the representation of each one of these symbols:
Note: this work is based in "BPMN Modeling and Reference Guide".