Polystyrene (PS) is a hard, stiff, and brilliantly transparent synthetic resin produced by the polymerization of styrene. At room temperature, polystyrene is a solid thermoplastic. It can be melted at higher temperatures for molding or extrusion processes and then resolidified into the desired shape. Styrene, the monomer from which polystyrene is derived, is an aromatic hydrocarbon, and polystyrene itself is classified as an aromatic polymer due to the presence of phenyl groups attached to its polymer backbone. These properties make polystyrene versatile and widely used in various applications, from packaging and consumer goods to insulation and medical devices. It is widely employed in the food-service industry as rigid trays and containers, disposable eating utensils, and foamed cups, plates, and bowls. Polystyrene is also copolymerized, or blended with other polymers, lending hardness and rigidity to a number of important plastic and rubber products.