Polypropylene (PP) is a tough, rigid, and crystalline thermoplastic. It is made from propene (or propylene) monomer. This linear hydrocarbon resin is the lightest polymer among all commodity plastics. PP comes either as homopolymer or as copolymer and can be greatly boosted with additives.
PP has become a material of choice, especially when you are looking for a polymer with superior strength (e.g., vs Polyamide) in engineering applications or simply looking for cost advantage in blow molding bottles (vs. PET).