Wheel stud
 

I broke a wheel stud, how do I take the old one out? Do I bang it out with a hammer? How do I put the new one in, the same way?

Thanks guys!

The shank of the stud has "splines" that lock into the hub. You knock out the old stud with a hammer. Then try to line up the splines on the new stud as best as you can, with the matching splines in the hub, so as not to mess them up. Then thread a lug nut on "backwards", with the flat side toward the hub, and tighten the lug nut, drawing the stud into place.

Yes you can use a hammer (that is what I did) or if need be a press. But a hammer is good.