It seems simple: tap the screen of your smartphone to open an app, or swipe your finger across the screen to make the smartphone do something else. However, that touch screen has been years in the making and is a complex piece of what is now essential technology. Readers will find out how layers of glass, metal, and LEDs work together to make a touch screen work. Full-color images augment explanations of different kinds of touch screens. Readers will be captivated by the many uses touch screens have in the world today, from controlling machinery in a factory to helping surgeons perform medical procedures.