Ink can be a complex medium, composed of solvents, pigments, dyes, resins, lubricants, solubilizers, surfactants, particulate matter, fluorescents, and other materials. The components of inks serve many purposes; the ink's carrier, colorants, and other additives affect the flow and thickness of the ink and its dry appearance Printing is putting words and images on paper by mechanical means. Books and newspapers are made by printing. Usually, the images are formed by ink. The ink is put on paper in machines called printing presses.