Alarm systems work with physical barriers, mechanical systems, and security guards to trigger a response when unauthorized access is detected. They consist of motion, contact, and glass break sensors. Video surveillance cameras can act as both a deterrent when visible and useful for verifying alarm incidents or analyzing past attacks. Access control methods monitor and control traffic through access points and areas using CCTV, identification cards, locks, doors, and gates. Identification systems and access policies also help manage ingress through security checks and authorization at entry points.