Pigment refers to the substance that can make objects colored. There are soluble and insoluble pigments, and there are differences between inorganic and organic pigments. Inorganic pigments are generally mineral substances. Humans have long known to use inorganic pigments to paint and paint their bodies on rock walls using colored soil and minerals. Organic pigments are generally taken from plants and marine animals, such as indigo, gambog and purple extracted from shellfish in ancient Rome.

Pigments differ from dyes in that general dyes can be dissolved in water (old distinction), while pigments are generally insoluble in water. Dyes are mainly used for dyeing textiles and other materials. However, this distinction is not very clear, because some dyes may also be insoluble in water, and pigments are also used for pigment printing and raw material coloring of textiles. The chemical structure of organic pigments is similar to that of organic dyes, so they are usually regarded as a branch of dyes.