Question: what are the three main categories of plastics?
Answer: 1 – Polyethylene Terephthalate (PET or PETE or Polyester) ... 
2 – High-Density Polyethylene (HDPE) ... 
3 – Polyvinyl Chloride (PVC) ... 
4 – Low-Density Polyethylene (LDPE) ... 
5 – Polypropylene (PP) ... 
6 – Polystyrene (PS) ... 
7 – Other.