A bony bowl
Put your hands on your hips. Feel that hard, curved edge under your hands? That's the top of your hip bones.
Your pelvis is shaped a bit like a bowl with no bottom. The word pelvis even comes from the Latin word for basin, a wide bowl.
It sits at the bottom of your backbone and on top of your legs. It is where your upper body and your legs meet.
Your pelvis has a left hip bone and a right hip bone. In the back, between them, is the sacrum, the triangle at the bottom of your backbone. Below that is your tailbone.
Three bones become one
Each hip bone starts out as 3 separate bones in a kid. There's a wide top part, a bottom part that you sit on, and a front part.
The three bones meet in the middle of your hip socket. During the teen years, they join into one solid bone, and the socket becomes one strong cup.
Try it: sit on your hands on a hard chair. Feel two bony bumps pressing down? Those are your sitting bones, the bottom parts of your hip bones.
Your hip joint
On each side of your pelvis is a deep, round socket. The ball at the top of your thigh bone fits snugly inside. This is a ball and socket joint.
The hip socket is much deeper than the shoulder socket. That makes your hip very steady for walking and running, though it can't swing quite as far as your shoulder.
The socket's science name, acetabulum, means little vinegar cup. People long ago thought it looked like the little cups they used for vinegar.
Try it: stand on one leg, holding on to something. Swing the other leg forward, back and out to the side. That's the ball turning in its socket.
Holding up and keeping safe
When you stand, the weight of your upper body goes down your backbone, into your pelvis, and out to your two legs. Your pelvis spreads the load, like the arch of a bridge.
The bowl shape also cradles soft parts in your belly. It guards your bladder, which holds pee, and parts of your intestines.
Lots of strong muscles hold on to your pelvis, like your glutes in your bottom and the big muscles of your thighs and belly.