In the 1880's another method of printing called lithography was developed. Litho is the Greek word for stone and lithography literally means writing on stones. 

Lithography was invented in 1798 by a man called Alois Senfelder. He was trying to find an inexpensive method of publishing his plays. He discovered that if he drew a design on a marble gravestone in wax crayons, then wet the stone and applied a greasy ink, the ink only stuck to the waxed areas of the stone. The image could then be copied onto a sheet of paper pressed against the stone. This method was used by the famous French Artist Toulouse Lautrec to create his famous series of posters of the theatres and restaurants of Paris. 

The process evolved slowly through the early part of the twentieth century, but as photographic processes grew more sophisticated, it became possible to create flexible metal plates coated with special photo-sensitive coatings. If a photographic stencil was made by photographing a page containing text and pictures, it could be laid on the plate and exposed to a bright light source. After developing, the exposed parts of the plate would then attract the greasy ink and the unexposed parts of the plate would attract water. The resultant "inky" image could then be transferred onto the paper. 

Lithography, or "litho", as it’s usually abbreviated, became popular for colour printing, but had much shorter run-lengths than letterpress until the plate technology improved. As "rotary" presses became commonplace, with cylinders holding the printing plates in place wrapped around cylinders, it was found that better results were gained by placing an additional cylinder covered in a rubber "blanket" in between the plate cylinder and the impression cylinder. This meant that the image was copied onto the smooth soft rubber surface rather than the abrasive surface of the paper. This new cylinder led to the use of the term "Offset Lithography". 

Because creating letterpress plates was rather long winded and required etching pictures onto metal surfaces and rather cumbersome and inflexible hot-metal typesetting, it has been surpassed around the globe by lithography. 

In the US printers tend to work with negative plates, whereas in Europe positive plates tend to be the norm.