Physical Security Glossary

Protection of facilities, equipment, personnel, and physical assets from unauthorized access, damage, or interference. Complements cybersecurity — a perfect firewall fails if an attacker can physically remove hardware.

A short, sturdy post (typically reinforced steel anchored in concrete) installed to prevent vehicles from accessing a protected area. Allows pedestrian passage while blocking vehicular intrusion. Common outside data centers, government buildings, and financial institutions.

A physical barrier used to block or restrict access. Broader than bollards — can include concrete blocks, jersey barriers, vehicles, or structural elements. Purpose: prevent vehicle access and channel people through controlled entry points.

A security-controlled entry chamber (also called a "man trap") between the exterior and interior of a building, consisting of two electronically-controlled doors. Ensures only a controlled number of individuals can enter at one time and that identity can be verified before interior access is granted.

Informal term for an access control vestibule. Refers to the ability to "trap" an unauthorized individual between the two doors — they can be locked in the chamber and detained for security response without ever gaining interior access.

An attack where an unauthorized person follows an authorized person through a secured door or entry point without presenting credentials. Access control vestibules and security awareness training are primary countermeasures.

A physical perimeter barrier that defines the boundary of a secured area. Can be transparent (chain-link) for monitoring, or opaque (solid panel) for privacy. High-security fencing is robust (cut-resistant) and tall (with razor wire to prevent climbing).

Sharp metal strips or coiled wire installed at the top of fences to prevent climbing. A common feature of high-security perimeters. Deters casual intrusion attempts by making fence-topping extremely dangerous.

A video surveillance system where cameras transmit signals to a specific, closed (not broadcast) network of monitors and recorders. "Closed circuit" means the signal is not publicly distributed. Modern CCTV systems are digital, networked, and include motion/object detection capabilities.

A camera feature that detects movement in the frame and automatically triggers alerts or recording. Reduces the need for continuous human monitoring — guards are only alerted when something actually moves in a monitored zone.

Advanced camera feature that can identify specific objects — license plates, faces, packages, weapons — within the camera's field of view. Enables automated identification of known vehicles or persons and can flag unrecognized individuals.

Also called dual control. A physical security policy requiring that two authorized individuals must both be present to access a sensitive area or asset. Neither person can enter or operate alone. Designed to prevent insider threats — a single person cannot be solely bribed, coerced, or compromised.

An identity credential (typically a card with photo, name, and RFID/smart chip) that grants physical access to secured areas. Must be worn visibly at all times in most secure facilities. Electronic badge systems log every entry and exit, creating an audit trail.

A sensor that detects infrared radiation (heat) emitted by warm bodies. Commonly used in motion detectors. Operates in both light and dark environments — unaffected by lighting conditions, making it ideal for server rooms and after-hours monitoring.

A sensor that detects changes in force or weight. Installed under floor mats, on window frames, or embedded in surfaces. Triggers when someone steps on a protected area or when force is applied to a secured window. Provides immediate intrusion detection at a point of contact.

A sensor that emits microwave signals and detects disturbances in the reflected signal caused by movement. Covers large areas with a single unit. Used for wide perimeter detection — parking lots, warehouse floors, exterior grounds — where infrared or pressure sensors would be impractical.

A sensor that emits ultrasonic sound waves and analyzes the reflected signals to detect motion, proximity, or collision. Used in enclosed spaces, server corridors, elevator lobbies, and automated systems. Can detect fine-grained movement that other sensor types might miss.

Applying multiple independent physical security layers so that failure of any single layer does not result in complete compromise. Example: fencing + vestibule + cameras + guards + sensors — each layer detects or prevents intrusion independently.