A horse's tail is a long, flowing extension of its spine, made up of hair that grows from the tailbone. It serves several purposes, including helping to keep flies and other insects away from the horse's body. The tail can also be a means of communication, as horses may swish their tails to express irritation or excitement. The hair in a horse's tail can vary in length, thickness, and color, depending on the breed and genetics. Some breeds, like the Arabian horse, are known for their long, luxurious tails, while others may have shorter, coarser tails. Proper care, including regular grooming, helps maintain the health and appearance of a horse's tail.