Diethylene glycol (DEG) is a clear, odorless, hygroscopic liquid made of two ethylene glycol units linked by an ether bond. It dissolves in water and many organic solvents, offering moderate viscosity and stability. Widely used as a solvent, it’s essential in producing polyester resins, plasticizers, coatings, inks, and brake fluids. DEG also acts as a moisture-control agent in gas dehydration, textile processing, and printing. Though versatile and efficient across industries, safe handling is critical due to its potential toxicity in high exposure.