Coal tar is a thick, black liquid produced during the carbonization of coal. It is a byproduct of the coking process, where coal is heated in the absence of air to create coke for steel production. Coal tar contains a complex mixture of organic compounds, including aromatic hydrocarbons, phenols, and heterocyclic compounds. Due to its chemical properties, coal tar is used in various applications, such as in the production of pavement sealants, dyes, and medications for skin conditions like psoriasis. It is also a source of valuable chemicals, including benzene and naphthalene, which are used in the manufacturing of plastics and other materials.