Hackamores are most often seen in western riding and other styles of riding derived from Spanish traditions, endurance riding, and are occasionally seen in some English riding disciplines such as show jumping and the stadium phase of eventing. While usually used to start young horses, they are often seen on mature horses with dental issues that make bit use painful and on horses with mouth or tongue injuries that would be aggravated by a bit. Some riders also like to use them in the winter to avoid putting a frozen metal bit into a horse's mouth.
Like a bit, a hackamore can be gentle or harsh, depending on the hands of the rider. It is a myth that a bit is cruel and a hackamore is gentler. The horse's face is very soft and sensitive with many nerve endings. Misuse of a hackamore can not only cause pain and swelling on the nose and jaw, but improper fitting combined with rough use can cause damage to the cartilage on the horse's nose, or even break the fine bones that protect the nasal passages.
The word "hackamore" is derived from the Spanish word jáquima,, meaning headstall or halter, itself derived from Old Spanish xaquima. The Spanish had obtained the term from the Arabic šakīma, (bit), from šakama (to bridle). From the Americanized pronunciation of jaquima, the spelling "hackamore" entered the written English language by 1850, not long after the Mexican-American War.
The first hackamore was probably a piece of rope placed around the nose or head of a horse not long after domestication, perhaps as early as 4,000 B.C. Early devices for controlling the horse may have been adapted from equipment used to control camels. Over time, more sophisticated means of using nose pressure were developed. The Persians beginning with the reign of Darius, circa 500 BC, were one of the first cultures known to have used a thick-plaited noseband to help the horse look and move in the same direction. This device, called a hakma, also added a third rein at the nose, and was an innovation that allowed a rider to achieve collection by helping the horse flex at the poll joint. The third rein later moved from the top of the noseband to under the chin, where it is still part of the modern mecate rein of the modern bosal-style hackamore. The techniques of horse-training refined by the Persians later influenced the works on horsemanship written by the Greek military commander Xenophon. This heavy noseband itself came to be known by many names, retaining the name hakma in Persio-Arabic tongues, but becoming the cavesson in French, and the bosal in Spanish.
The tradition of hackamore use in the United States came from the Spanish Californians, who were well-respected for their horse handling abilities. From this tradition, the American cowboy adopted the hackamore and two schools of use developed: The "buckaroo" or "California" tradition, most closely resembling that of the original vaqueros, and the "Texas" tradition, which melded some Spanish technique with methods from the eastern states, creating a separate and unique style indigenous to the region. Today, it is the best known of the assorted "bitless bridling" systems of controlling the horse.
The word "hackamore" has been defined many ways, both as a halter and as a type of bitless bridle. However, both terms are primarily descriptive. The traditional jaquima hackamore is made up of a headstall, bosal and mecate tied into looped reins and a lead rope. It is neither precisely a halter nor simply a bridle without a bit. "Anyone who makes the statement that a hackamore is just another type of halter . . . is simply admitting that he knows nothing about this fine piece of equipment."
Today, hackamores can be made of leather, rawhide, rope, cable or various plastics, sometimes in conjunction with metal parts. There are three main types: the bosal, the sidepull, and other assorted designs, often classed as "bitless bridles."
The bosal acts on the horse's nose and jaw, and is most commonly used to start young horses under saddle in the Vaquero tradition of the "California style" cowboy. The bosal is a very sophisticated and versatile style of hackamore. Bosals come in varying diameters and weights, allowing a more skilled horse to "graduate" into ever lighter equipment. Once a young horse is solidly trained with a bosal, a bit is added and the horse is gradually shifted from the hackamore to a bit. While designed to be gentle, Bosals are equipment intended for use by experienced trainers and should not be used by beginners, as they can be harsh in the wrong hands.
English riders sometimes use a jumping cavesson, or jumping hackamore, which is a type of hackamore that consists of a heavy leather nosepiece (usually with a cable or rope inside) with rings on the sides for reins, similar to a sidepull, but more closely fitting and able to transmit more subtle commands. A jumping cavesson is put on a standard English-style headstall and often is indistinguishable at a distance from a standard bridle. It is often used on horses who cannot tolerate a bit or on those who have mouth or tongue injuries.