In liability insurance, the trigger is the event that brings coverage into play. It may be either an occurrence of bodily injury or property damage or, in a form with a claims-made trigger, the formal making of a claim.
***
A mechanism that determines whether a policy covers a particular claim for loss. For example, the difference between the coverage triggers of liability “occurrence” forms and “claims made” forms is that loss must occur during the policy period in the first case and claim must be made during the policy period in the second case.