The document discusses the history and technologies of touchscreens. It notes that the first touch sensor was developed in 1971 by Dr. Sam Hurst. In 1974, Hurst and Elographics developed the first true touchscreen with a transparent surface. There are four main touchscreen technologies - resistive, capacitive, infrared, and optical imaging. Resistive touchscreens work by pressing two flexible sheets together. Capacitive screens detect changes in capacitance from a finger touch. Infrared screens use LED beams to detect touches. Optical imaging uses cameras to locate touches.