Small Of Her Back

I have read many books and have come across the phrase 'small of my/her/your/his back' so many times.

But like most words and phrases I don't know, I never bothered to find out what it means.

Then I saw the phrase again in a new book I was reading and finally decided to go find out where the small of the back actually is.

Answer : The part of your right above the top of the pants.

He rested his hands on the small of her back as they began dancing.

Now I know.