Xenography

The technology behind photocopying and the birth of Xerox is known as electrostatics — exposing light onto a charged metal plate, dusting the plate with a powder that picks up an image, and then transferring the image to paper electrostatically. Got that? The process was developed in 1938 by Chester Carlson, an employee at a New York electronics firm who was frustrated by the difficulty of copying documents. In 1947, the Haloid Company (later named Xerox) bought the rights to Carlson's xerography process, and 11 years later, the first Xerox office copier was born, becoming standard equipment in offices worldwide.

Source: http://content.time.com/time/photogallery/0,29307,2026224,00.html