Rein

Reins are items of horse tack, used to direct a horse or other animal used for riding or driving. Reins can be made of leather, nylon, metal, or other materials, and attach to a bridle via either its bit or its noseband.

Reins are used to give subtle commands or cues, also known as rein aids. Various commands may signal a turn, ask for a slower speed, request a halt or rein back. Rein aids are used along with leg aids, shifting of body weight, and sometimes voice commands.

On some types of harnesses there might be supporting rings or "terrets" used to carry the reins over the animal's back. When pairs of equines are used in drawing a wagon or coach it is usual for the outer side of each pair to be connected to the reins and for the inside of the bits to be connected between the pair of horses by a short bridging strap or rope. The driver carries "four-in-hand" or "six-in-hand" being the number of reins connecting to the pairs.

A single rein or rope may be attached to a halter to lead or guide a horse or packhorse. A long rein called a longe line may be used to allow the horse to move in a circle for training purposes, or for the purpose of a clinical lameness evaluation by a veterinarian. On certain designs of headgear, a third rein may be added to the paired reins, used for leading, longeing, or other specialized or stylistic purposes. The best-known example of a third rein used in the USA is the leading rein of the mecate of the classic bosal hackamore.

Types of reins include:

In popular culture, to rein in means to hold back, slow down, control or limit. Sometimes the eggcorn, reign in, is used. Usage of the opposing free rein dates back to Geoffrey Chaucer (1343–1400) and means to give or allow complete freedom, in action and decision, over something.

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