Lithography is a printing process that works on the principle that oil and water do not mix. The technique was invented in 1796 by German author Alois Senefelder and is still widely used today for fine art prints and posters.
Artists draw directly onto a smooth limestone surface or specially prepared metal plate using greasy materials. The surface is then treated with chemicals to fix the image, and when ink is applied, it adheres only to the drawn areas.