IV vs. OTM puts and OTM calls

I having trouble interpreting a volatility graph, that involves skew. It has the vertical axis of IV of a period of time, against the OTM puts and OTM calls.

Most of the graphs are concave and are downward sloping until they hook at the end of the graph, why is that?

Are there any tips on what to do with this information that is presented?

What are abnormalities that can be taken advantage of for trading purposes?

Of course there are always different scenarios that could occur, but i am basically looking for information that would benefit me in the analysis of this graph, and how i can use it to my advantage when trading options.

I am not sure what you mean by "concave and are downward sloping until they hook at the end of the graph". Can you produce an illustration of this shape and maybe I can help?

In terms of what to do, it all depends on your view on whether OTM options are cheap or expensive. There are various strategies that can be used to express your view.