Dado Rail or Something Else?

I'm writing an article at the moment and I was just about to talk about dado rails when I suddenly wondered if this was a term that you used in the US (I've been caught out with things like this before).   I know some people call them chair rails, but I don't know of any other terminology.

I've heard the term chair rails used.

I didn't know what it was, until I looked it up on Google.com. Seems to be a pretty common term in the US.

Thanks Lil, I'll use chair rails instead.

Oh, we posted at the same time Chef - okay I'm more comfortable with Dado so maybe I'll go with both terms and see how it looks.

Good additional keyword for free there Lou. You get the opportunity to state something like, 'These chair rails are a cinch to put together for your chair, sometimes called Dado rails in the US.....' etc etc

I don't know what they are.  Okay, looked it up too.

I guess chair rail is what I've heard it called.

Are chair rails to prevent the chairs of say a dining room from banging the walls leaving marks?

Thanks for all the replies 

@Katie - I believe that they were originally used for that purpose in dining rooms, but they then morphed into being used in lots of rooms just for decorative purposes - my first house had them in the entrance (it was like a little room, but not big enough to use as one) and in the hallway when we moved in and as it was an older house it actually suited it.   

They've gone out of fashion as people really overdid them, but one of my friends uses the technique in both of her children's bedrooms and it works really well as she does it with a modern twist.