Burglar (or intrusion), fire, and safety alarms are electronic alarms designed to alert the user to a specific danger. Sensors are connected to a control unit via low-voltage wiring or a narrowband RF signal which is used to interact with a response device. The most common security sensors are used to indicate the opening of a door or window or detect motion via passive infrared (PIR). New construction systems are predominately hardwired for economy. Retrofit installations often use wireless systems for a faster, more economical installation. Some systems serve a single purpose of burglar or fire protection. Combination systems provide both fire and intrusion protection. Systems range from small, self-contained noisemakers, to complicated, multi-zoned systems with color-coded computer monitor outputs. See also fire alarm control panel for specific fire system issues. Burglar alarms are sometimes referred to as alarm systems, see burglar alarm control panel for a discussion of hard-wired burglar alarm system design.

Burglar alarms (or perimeter security systems, perimeter detection systems, Perimeter protection, intrusion detection systems and many more terms for the same thing) are divided to two main fields: home burglar alarms and industrial burglar and perimeter intrusion detection.

Alarm types

Indoor

These types of sensors are designed for indoor use. Outdoor use would not be advised due to false alarm vulnerability and weather durability. Some indoor detectors {Passive infrared detectors-Ultrasonic detectors-Microwave detectors}

Outdoor

These types of sensors would be found most of the time mounted on fences or installed on the perimeter of the protected area. Some outdoor detectors {Passive magnetic field detection- Microwave barriers}