Polystyrene is a polymer produced by the polymerization of styrene. It is a hard, thermoplastic with high dielectric properties, low water absorption, good dimensional stability, and glass-like transparency. Polystyrene is shiny, easily colorable, and odorless. It is normally resistant to acids, bases, alcohols, oils, and salt solutions; however, it catches fire easily, burns with a luminous flame, emits dark smoke, and produces a distinctive odor when burning.

Polystyrene is among the top five most used general-purpose plastics worldwide due to its transparency, ease of processing, fluidity, suitability for food contact, and many other properties. It is classified into different types according to the processing method: High Impact Polystyrene (HIPS), General Purpose Polystyrene (GPPS), and Expanded Polystyrene (EPS). Due to its cost-effectiveness, it is widely used in various industries as an alternative to paper, wood, and metal.