How to tell if lenses have focus motor in them?

I want to get a new lens for my nikon d5000 but I know that it isn't built with an auto focus motor in the camera. How do I tell if the lens I'm buying will auto focus. Are there letters saying that our no. Like what is afi afs.

Http://www.nikonzoomlens.info/?p=43

You want the AF-S lenses.

Nikon AF-S, sigma HSM and tamron Build-in-Motor will autofocus.