Polyester is any of a group of widely used plastics materials. The most important polyester, polyethylene terephthalate (PET), can be spun into fibre, extruded (pushed through an opening) to make film, or combined with other materials and moulded into plastic parts. PET is a thermoplastic, meaning it softens and melts at high temperatures. PET fibre is one of the most widely produced synthetic fibres. It appears in such products as tyre cords and clothing. It is strong and flexible, and it resists wrinkling and mildew. Many PET fibre is sold under the name Dacron, a registered trademark of the DuPont Company. Uses of PET film include magnetic tapes and shrink wrap. PET is also used to make plastic soft drink bottles, which, like PET film, are clear and tough, and resist water and chemicals.