Stallion
A Stallion is a male horse that has not been castrated. They usually have a thicker, "cresty" neck compared to mares and geldings, as well as a more muscular physique and a fiery temperament.

Due to hormonal differences, a stallion can be more aggressive than a gelding, though stallions are useful for breeding. Such hormonal surges, especially testosterone, cause stallions to be more unpredictable than other horses. Stallions exhibit sex-driven dominance behaviors, specifically biting, squaring-up and rearing.

Stallions are generally more "fiery" than the average mare, and may have a competitive edge. They are especially popular for upper level dressage work, as well as show jumping. Stallions are rarely seen at the upper levels of eventing.

Due to their nature, stallions should be handled and ridden by an experienced rider, as a novice rider usually does not have the knowledge to control the horse during riding, and inexperienced handlers could be harmed or overpowered.

Although stallions are generally more fiery than mares, this is not always the case. It depends very much on breeding, training, and each horse's own temperament. Some stallions can be ridden by beginner/novice riders, but this is generally not recommended. Any specific stallion's owner and/or trainer will know their horse well enough to tell whether he is calm and safe enough for beginner/novice riders.