A harness is a set of straps that are put on a horse so it can be hitched to a wagon or a carriage. The harness distributes the effort across larger sections of the horse's body.
Harnesses have also been used in fashion. It can be intricate and fetish-inspired, and is essentially a combination of belt-like shapes meant to hug and highlight the body, usually the shoulders or chest. Do note that harnesses don’t have to be leather.