What is ink classified as in terms of art materials?

Ink is classified as a liquid pigment because it consists of pigment particles suspended in a liquid medium, allowing it to flow and be applied with various tools, such as pens or brushes. This property enables ink to be used effectively for drawing, calligraphy, and printing, providing a wide range of colors and finishes depending on the formulation and application technique. The fluid nature of ink distinguishes it from solid pigments, which require a different application method, and further differentiates it from other materials like chalk or metal-based mediums that have distinct characteristics and uses in art.