Photocopying

Photocopying, duplication of printed images or words through a process involving photographic techniques. The most popular of these techniques, Xerography (1938), is a dry process in which light-sensitive material is charged with static electricity to produce an image when a toner (powdered ink) adheres to heated paper and recreates the original image. Older processes depended on liquid developers, such as photostats and blueprints. Libraries and other document storage facilities use microfilming to make miniature copies, up to 1/100th the original size.