A curb bit is a bit with a solid or broken mouthpiece and shanks.
The headstall is attached to upper shanks and the reins are attached to lower shanks of a curb bit. A curb bit applies leverage pressure and, as such, increases the amount of pressure from the reins to contact points in and around the horse's mouth.
In general, curbs are designed to be used with no rein contact unless the rider is applying a specific cue.
For more information about bits, check out the learning lesson Understanding Bits for Horses.
