Recycling symbols explained

This is a good article that walks you through the triangular symbol containing a number between '1' and '7'. From PETE (polyethylene terephthalate) to "Other".

In our NJ neighborhood, they recycle 1 and 2 - polyethylene terephthalate and HDPE (high density polyethylene). One thing I haven't found out, but will Google now) is where they have two numbers on one container. I suspect the second number is for the cap or lid, but it's not very clear.