Toluene is a colorless water-insoluble aromatic hydrocarbon with a smell usually associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group attached to a phenyl group. It is widely used as an industrial feedstock and a solvent. As the solvent in some types of paint thinner, contact cement and model airplane glue, toluene is sometimes used as a recreational inhalant and has the potential of causing severe neurological harm.