1. What material the item is made of or the art is produced on. Examples include paper (white), black paper, canvas, board, cel (acetate), sculptures…
2. The specific tool and material used by an artist, e.g., brush and oil paint, chisel and stone.
3. The mode of expression employed by an artist, e.g., painting, sculpture, the graphic arts.
4. A liquid that may be added to a paint to increase its manipulability without decreasing its adhesive, binding or film-forming properties.