Every record is first classified by what it is. The distinction drives the level of
response and the reporting obligations, and it can change after review — an event
that turns out to threaten data becomes an incident; one that discloses personal or
sensitive information becomes a breach.
Event An observable, significant occurrence in a system or network that may result in a change to normal behaviour — a suspicious login, a malware alert. All incidents are events; many events are not incidents.
Incident An adverse event that threatens the confidentiality, integrity, or availability of data or systems: a policy violation, unauthorized access, loss of confidentiality or availability, denial of service, or misuse of a service or system.
Breach Unauthorized access to, or disclosure of, personal or sensitive information.