Bits The bit rests against the sensitive bars of the horse's mouth, and conveys instructions (aids) to him from the rider's hands. The reins connect the hands to the bit. With training, the horse learns to accept the bit, to understand the instructions given by movements of  the rider's hands, and to obey immediately.

The variety of bits available in tack shops and at sales can be bewildering. In choosing a bit for a horse, it is essential to bear in mind what sort of mouth he has and what sort of work he will do.

Bits work by acting on the bars inside the horse's mouth, which in a young horse are very sensitive. 'Hard' mouths result when the nerves that lie under the bars are destroyed, usually by rough handling. A horse with a hard mouth is, naturally, less responsive to its rider's wishes communicated through the bit.

The bit must fit the horse's mouth in width or it will not work well. The thicker and smoother the mouth- piece, and the smaller the angle of leverage from the rein, the milder a bit will be in action. Thin bits and those that are twisted have long check pieces, or ride up in the mouth, are generally severe on the horse; and the more severe the bit the better the more sensitive-the rider's hands must be.