Polyethylene terephthalate or polyethylene terephthalate (trade names: Arnite, Impet and Rynite, Ertalyte, Hostaphan, Melinex and Mylar films, and the fibers Dacron, Diolen, Tergal, Terital, Terylene and Trevira), is a member of the polyester family and is a thermoplastic resin composed of phthalates suitable for food contact.

Depending on production processes and thermal history, it can exist in amorphous (transparent) or semi-crystalline (white and opaque) form.
It is also used for its electrical properties, chemical resistance, high-temperature performance, self-extinguishing, and quick molding.

It is also referred to as PET, PETE, PETP or PET-P.
PET decomposes at a temperature of 340 °C, forming acetaldehyde and other compounds.