Motion detectors are devices that detect movement in a given area. They are often used in security systems to detect intruders or other unauthorized activity. Motion detectors use SENSORS to detect changes in the environment, such as changes in temperature, light, sound, or pressure. When a change is detected, an alarm is triggered. Motion detectors can also be used to detect animals or other objects in a given area. Motion detectors are an important part of home and business security systems, as they provide an extra layer of protection against unwanted intruders.