Whenever something moves inside the active radius of this sensor it triggers the camera according to your specifications. This sensor is triggered by motion. As soon as the sensor is powered on it will take a "snap shot" of the area it is in and if something changes in that area then it will react. You can use this for night photography when you want to capture animals while they pass by or in general for anything that you want to capture in motion. As always try to use your imagination :) There are endless applications for this sensor.