Xerography

Xerography (or electrophotography) is a dry photocopying technique invented by Chester Carlson in 1938, for which he was awarded a U.S. Patent on October 6, 1942. Carlson originally called his invention electrophotography. It was later renamed xerography mdash; from the Greek roots xeros (dry) and graphos (writing) &mdash; to emphasize that, unlike reproduction techniques then in use such as cyanotype, this process used no liquid chemicals.