Blue dye is a type of coloring agent used to create a variety of shades of blue. ANIL, WOAD, Marge, INDIGO, CYAN, Azo, LITMUS, and HENNA are all types of blue dyes. ANIL is a synthetic dye derived from coal tar, while WOAD is a natural dye made from the leaves of the plant Isatis tinctoria. Marge is a synthetic dye made from aniline, INDIGO is a natural dye made from the plant Indigofera tinctoria, and CYAN is a synthetic dye made from coal tar. Azo is a synthetic dye made from aniline and phenol, LITMUS is a natural dye made from lichens, and HENNA is a natural dye made from the leaves of the Lawsonia inermis plant.