Polyethylene terephthalat frequently shortened to PET or PETE and was formerly called PETP or PET-P.

It is an ethane derived plastic.

PET or PETE  (plastic code 1) is most often used for making fibers, things made by injection molding, and containers for food, drinks, pharmaceuticals, make-up etc.

PET fibers are used with other fibers to strengthen them, to make a fiber filling, for fabrics, and carpets,  automobile tire yarns, conveyor belts and seat belts, for non woven fabrics for stabilizing drainage ditches, culverts, and railroad beds, disposable fabrics for use in medical applications, sanitary protection, menstrual products and nappies.

Its other major use is for bottles and  jars for food processed at low temperatures.

It can be used to make a clear containers allowing the contents to be easily seen and identified.

It is intended for single use food packaging applications as repeated use is said to increase the risk of chemicals leaching from the plastic into the contents. There are claims that some of these chemicals may be carcinogenic and or endocrine disruptors.

PET is only 10% of the weight of an identical glass container, it allows for less expensive shipping and handling, saving a significant amount of money for companies around the world.” Copied from Wise Geek

PET starts softening at around 70 °C (160 °F).

It is claimed that bacteria can  colonise the rough surface of a PET.

PET plastic is an easily recyclable plastic  and about 25% of PET bottles in the US today are recycled.

It is made from carbon, hydrogen and oxygen, just like paper. It is claimed that, just like paper, it can be safely burnt and will only produce carbon dioxide and water leaving no toxic residue.

However the Material Safety Data Sheet for PET states

Can burn in a fire creating dense toxic smoke. Molten plastic can cause severe thermal burns. Fumes produced during melt processing may cause eye, skin and respiratory tract irritation.