Polyethylene terephthalate, commonly abbreviated PET or PETE and is a thermoplastic polymer resin of the polyester family. And is used in beverage, food and other liquid containers, and in thermoforming applications and engineering resins often in combination with glass fibre.

Depending on its processing and thermal history, polyethylene terephthalate may exist both as an amorphous (transparent) and as a semi-crystalline material.

The semicrystalline material might appear transparent with a colour pigment added. The majority of the world’s PET production is for synthetic fibers (in excess of 60%) with bottle production accounting for around 30% of global demand.

In discussing textile applications, PET is generally referred to as simply “polyester” while “PET” is used most often to refer to packaging applications.