Photocopying

Photocopying is the process by which light is used to make copies of book pages and other paper documents. Today the most widely used form of photocopying is xerography ("dry writing"), invented by New York patent attorney Chester Carlson in the 1930s. Indeed, the name of the company founded to develop Carlson's invention, Xerox Corporation, has become synonymous with the process of photocopying. However, a number of other forms of photocopying pre-dated the Carlson invention and are still used for special applications. Among these other forms of photocopying are thermography, diazo processes, and electrostatic copying.