Plastics are all around us — from food packaging and drinking bottles to the insulation in our homes. They are mostly all derived from fossil fuels like oil and natural gas, but what are the key differences between each type of plastic? Here is a brief guide to the most commonly used plastics and their acronyms, as classified by the Organisation for Economic Cooperation and Development (OECD). Three main families: Thermoplastics are the most common plastics, because they are so malleable when heated, and can be remelted. Elastomers, meanwhile, can be stretched to a great extent and then regain their original form. And thermosets are resins that become irreversibly hard when heated. Within each family, an infinite number of polymers are mixed with a wide range of additives that are sometimes harmful to the environment or health. These additives can change the colour of plastics, prevent ageing, make them flexible, increase impact resistance, or reduce flammability. PP: Polypropylene, or PP, is the most widespread plastic in the world (16 percent), developed in the mid-1950s and used for automobile parts and food packaging as well as disposable trays. HDPE and LDPE High and low density polyethylenes each represent 12 percent of global plastic use, according to the OECD. HDPE, invented in 1933 by British engineers, is used for toys, shampoo bottles, pipes, engine oil cans and a variety of household objects. LDPE, developed later in the 1950s, is widely used to manufacture flexible products such as reusable bags and food packaging film. PVC: Polyvinyl chloride (PVC) is mainly used in construction for window frames, floor covering, pipes or cable insulation. It represents 11 percent of global plastic. PS: Polystyrene (PS), invented in 1931 by IG Farben, represents five percent of the world’s plastic and is mainly used for food packaging.