Thermosetting plastic is a type of polymer that becomes permanently hard when heated and molded. Unlike other plastics, which can be remolded, thermosetting plastics undergo a chemical change during the curing process, making them rigid and heat-resistant. Common examples include epoxy, melamine, and phenolic resins. These materials are widely used in various applications, such as electrical insulators, automotive parts, and kitchenware. Their durability and resistance to heat and chemicals make them ideal for products that require strength and stability. Once set, thermosetting plastics cannot be reshaped, ensuring they maintain their form under stress.