What do the numbers on bottom of bottles indicate?

I recently came across another chain mail, about the numbers below plastic bottles we use. According to this mail, the number (generally within a triangle) written at the bottom, which ranges from one to seven, indicates how many times that particular plastic is recycled in reverse order. I dug a little deeper. Apparently, the number printed has nothing to do with the number of times plastic has been recycled.  It’s just the type of plastic which is used for that particular bottle. 5 is polypropylene and 1 is polyethlyene terephthalate etc etc.

One primary use of having the numbers if to help recyclers to sort into appropriate groups. In other words, identification number.

1 – PET, polyethlyene terephthalate
2 – HDPE, high-density polyethylene
3 – PVC, polyvinyl chloride
4 – LDPE, low-density polyethylene
5 – PP, polypropylene
6 – PS/PS-E, polystyrene / expanded polystyrene
7 – OTHER, resins or multi-materials

What…