Offset printing, also called offset lithography, or litho-offset, in commercial printing, widely used printing technique in which the inked image on a printing plate is printed on a rubber cylinder and then transferred (i.e., offset) to paper or other material. The rubber cylinder gives great flexibility, permitting printing on wood, cloth, metal, leather, and rough paper. An American printer, Ira W. Rubel, of Nutley, N.J., accidentally discovered the process in 1904 and soon built a press to exploit it.
In offset printing the matter to be printed is neither raised above the surface of the printing plate (as in letterpress) nor sunk below it (as in intaglio, or gravure, printing). Instead, it is flush with the surface of the plate; thus offset is classified as a planographic method of printing.