What Is a Computer Incident?
Although the term “computer incident” is frequently used in many forums, it does not have a universally accepted definition. The following are some examples of how the term is defined in just a few publications:
Incidents are events that interrupt normal operating procedures and precipitate some level of crisis. Specifically, incidents are computer intrusions, denial-of-service attacks, insiders' theft of information, and any unauthorized or unlawful network-based activity that require computer security personnel, system administrators, or computer crime investigators to respond.
 Mandia, Kevin, and Chris Prosise. Incident Response Investigating Computer Crime. Berkeley, CA: Osborne/McGraw-Hill Publishing, 2001, ...