Events trigger changes in the state of business objects and communications between actors.

Events relevant to HR collaborations can be broadly categorized as:

• Personal (for example, a employee change of address, marriage, divorce, disability, etc.)
• Employment and work-related (hire, termination, promotion, etc.);
• Organizational (merger, acquisition; plant closing; bankruptcy; policy changes; vendor changes; etc.); and
• Process specific (for example, successful completion of employment screening may clear the way for a next step or stage of a hiring process).

There can be relationships and priorities among different events. One event may trigger another. Likewise, the occurrence of a certain event may supersede another as a trigger for a collaboration.

An "event driven architecture" is a style of application and system architecture characterized by a set of relatively independent actors working towards coordinated goals by communicating and responding in predictable ways on the basis of event triggers.