"Open hips"?

[Peter Möller]

I was a bit unsure where to post this so if it´s the wrong section I´m sorry. But I keep reading about it in alot of sports/fitness related texts so I figured this section would be ok.
Anyway, what exactly is meant by having an open hip? Might be a really basic question but again I´m unsure. For example I read when doing dynamic stretching such as butt kicks, to really stretch the femoris and psoas it´s essential to have an open hip.
So, a little help with defining an open and closed hip?

[Joshua Williams]

Open/closed is referring to the angle formed at the hips by the upper leg and your torso.

Think of your thigh as the cover of a book and your stomach the back of a book and the spine of the book is at the crease where your thigh intersects with your hip.

When the book is closed...the thigh touches the stomach. When the book is open...there is no bend at all at your hip and you are standing fully erect.

[Peter Möller]

Thanks alot! Books... That I can remember!:p