This document discusses speed cameras and how they work to enforce speed limits. It describes how speed cameras use technologies like piezo sensors, radar guns, and infrared sensors to detect if vehicles are speeding. When a vehicle exceeds the speed limit, the camera takes a digital image that records the vehicle's speed, time, and license plate number. The document also outlines some benefits of speed cameras, like reducing accidents and saving lives, as well as some criticisms that they are just a tax on wealthy drivers or that speed is not the main cause of accidents.