An induction or inductive loop is an electromagnetic communication or detection system which uses a moving magnet or an alternating current to induce an electric current in a nearby wire. Induction loops are used for transmission and reception of communication signals, or for detection of metal objects in metal detectors or vehicle presence indicators. A common modern use for induction loops is to provide hearing assistance to hearing-aid users.

Traffic lights, traffic signals, or stoplights – also known as robots in South Africa and Namibia – are signalling devices positioned at road intersections, pedestrian crossings, and other locations in order to control the flow of traffic.