"Polyethene terephthalate, or PET, is a type of plastic resin as well as a form of polyester. It can be fully recycled, in which case it becomes recycled polyethene terephthalate or rPET. Essentially, the material is a polymer, which is made by combining purified terephthalic acid and modified ethylene glycol, both monomers. PET was originally discovered in 1941 in the United Kingdom, where it was also patented.
If you grab a container or bottle, you may notice a #1 code on the bottom of it. That is to say, it is made out of PET. It is very common as a packaging material, including things like peanut butter, beverages, produce, bakery goods, salad, frozen foods, cosmetics, dressings, and household cleaners. PET itself is incredibly popular because it is transparent, thermo-stable and incredibly durable. Additionally, it is lightweight, affordable, shatter-resistant, resealable and, most important of all, recyclable. This is where rPET comes in."