Coal liquid, also known as coal TAR, is a thick black liquid produced when coal is heated in the absence of air. It is composed of hundreds of different compounds, including phenols, polycyclic aromatic hydrocarbons, and heterocyclic compounds. TAR is used in a variety of industrial applications, such as in the production of dyes, paints, and asphalt. It can also be used to produce fuel oil and other products. The three-letter acronym for coal liquid is TAR.