Reins, which attach to the bit or noseband, are the main connection between rider and horse. The right reins facilitate being able to command, stop and steer a horse or pony, and are thus a key piece of tack.
Reins usually come along with a bridle when you purchase it, but for one reason or another you may wish to replace or renew your reins, adapting them for different types of riding or upgrading the quality.
The most common types of reins are closed or loop reins, usually a single strap which is easy to hold. Curb and Snaffle reins match the type of bits of the same names, and double reins - used by experts in top level events such as dressage or polo - attach to a double bridle. Then there are long driving reins used for training or to steer a horse harnessed to a cart. Side reins are used for lunging and Mecate, Romel and Split reins are usually used in Western syle riding.
Reins come in different lengths (obviously to suit the size of the horse or pony), widths and materials, rubber and leather being the favoured options.