This is a transcript of an illustrated talk explaining the global positioning system (GPS) to sixth-form general studies students, the target audience being science and non-science students. Explanation of the use of a compass is followed by a simple introduction to the mathematical techniques behind GPS. The early Earth satellites are described and orbiting times are explained. This leads on to detail of the present generation of satellites used for GPS, and how the necessary measurements are used to provide the information on the position of the receiver.