Humans have used color as a means of expression since the prehistoric ages. From scratches on trees and rocks, food or water indicators, territorial markers, to painted images in caves and other surfaces, the applicability of colorants or pigments has continued to broaden significantly over the years.
This, in turn, has contributed to persistent efforts towards developing better pigment technologies. The earliest known pigments used by ancient civilizations were derived from natural sources such as ground minerals and charcoal, among others. Many cave paintings from the Paleolithic and Neolithic eras feature yellow ochre (hydrated iron oxide, Fe2O3·H2O), red ochre (iron oxide, Fe2O3), and carbon black, indicating that these pigments were known to prehistoric humans.