Xerography or
electrophotography is a dry
photocopying technique. Its fundamental principle was invented by Hungarian physicist
Pál Selényi and based on Selényi's publications
Chester Carlson applied for and was awarded on October 6, 1942. The technique was originally called electrophotography. It was later renamed
xerography—from the
Greek roots xeros, "dry" and
-graphia, "writing"—to emphasize that, unlike reproduction techniques then in use such as
cyanotype, this process used no liquid
chemicals.