Learn in the textbookPhysical Security Measures
DefinitionA surveillance camera films and records entrances and important areas to keep watch on people's movements.
ExplanationSimply knowing a camera is there makes people think twice, which gives it a deterrent effect. The footage also serves as an audit trail (証跡) for tracing what happened after an incident. Recordings are kept for a set retention period, and cameras are placed so that no blind spots remain.