A tact switch ;is a type of switch that is used every day but hardly ever seen. Hidden under every key of a computer keyboard, the tactile switch is small and thin, but features high reliability to ensure it will operate for years or even decades. The main job is to turn on or off the flow of electricity in an electrical circuit. These devices are used in all types of equipment, from kitchen appliances to sophisticated industrial machines. A little bit of background on the device will help explain how it works.http://www.led-tact-switch.com/tact-switch/