A finely ground, insoluble colouring material mixed into paint, ink or other media.
Pigments remain as discrete particles suspended in a binder, unlike dyes, which dissolve into the material they colour — this is the defining physical difference between the two.
'Pigment' and 'dye' are often used interchangeably in everyday speech, but they are physically different (see dye).
Ochre and ultramarine are historical pigments — see the pigments & dyes section for structured records.
Whether a colourant is a pigment or a dye affects its lightfastness, cost and historical availability.