Name a common type of security technology used in the field.

Closed-circuit television (CCTV) is a prevalent type of security technology utilized widely in various settings, including public spaces, businesses, and private properties. Its primary function is to provide surveillance through video feeds that are transmitted to a limited number of monitors, allowing security personnel to monitor activities in real-time or review recorded footage later. CCTV serves as an effective deterrent against criminal behavior, enhances security by increasing the perception of being watched, and aids in incident investigation by providing visual evidence.

While other options like metal detectors, radio communication, and bulletproof vests play important roles in security, they serve different purposes. Metal detectors are primarily used to screen for weapons or prohibited items; radio communication facilitates coordination among security personnel; and bulletproof vests provide personal protection rather than serving as surveillance tools. Each of these technologies contributes to overall safety and security, but CCTV's application in monitoring and recording makes it a standout technology in the field of security.