GPS tracking devices can be used to track people, vehicles and other assets, anywhere on Earth. Currently, there are 27 satellites orbiting the earth, 24 are operational, the other three will become operational if one of the satellites happen to fail. At any given time there are at least three satellites that are visible in the sky from a location. These satellites then triangulate on the position of the GPS tracking device. By continuing to triangulate the coordinates at regular intervals, the satellites can determine the speed of an object, the distance traveled and how long it has been stationary.
There are two main types of GPS tracking systems currently on the market today. They are classified as Passive and active (real-time).