Plastic #2, also known as High-Density Polyethylene (HDPE)

HDPE is also recyclable and is considered to be a more environmentally friendly option compared to other types of plastic, as it can be easily reprocessed and used in the production of new products.

HDPE is lightweight and strong. It is also resistant to moisture, chemicals, and UV light. These properties make it popular for outdoor uses.

HDPE is often used for:

HDPE is widely recognized as one of the easiest plastics to recycle and is widely accepted by recycling programs. It has a recycling rate of around 31% in the US. 

The colour of HDPE also affects its recycling rate: HDPE that is clear or natural in color is much easier to sort and recycle than coloured HDPE. 

So in practice, your plastic milk bottle is more likely to get recycled than your pink shampoo bottle even though both are made from HDPE.

Here's a short video by plastic experts explaining the properties of HDPE: Packaging Polymers 101 HDPE